F650 Valve Misc FAQ
compiled & edited by Kristian #562
Please read the Disclaimer before
attempting any work in this FAQ.
Last Updated: 16 Feb 2007, by Winter #1935
For other related FAQs:
What do I do if the clearances are too big for available Shims?
- If you need a bigger than available shim, that means that your valve
does not stick up above the head far enough. Probably the easiest thing to do
is take the head off and take it to a good machine shop that does valve work
and have them dress the seat of the offending valve. Taking material off the
seat will make the valve stick further though the head, necessitating a smaller
shim. Cost you a head gasket and about a half hour of a machinist's time. Not
that big a deal if it is out of warranty or if you have done any work
whatsoever on it yourself. If it was still IN warranty and had been 100% dealer
maintained (then you wouldn't know what you do), I would suggest you ride the
piss out of it until it burns the valve and BMW has to give you a new head or
at least replace the valve and re-cut the seat. Flash #412 (CO)
- Digging thru the manual, chart on
11.6, I notice that BMW lists two different (by .15mm) specs for valve stem
lengths. If I'm lucky, if/when my intake valves keep receding and I run out of
clearance, I MIGHT have the longer valve, and can replace it with the shorter
one, getting another 2-3 years without major head work. Much easier to replace
a valve than to machine a seat. Then again, when the time comes, assuming my
compression is still good and if I were going to CHEAT, I'm wondering how long
things will last if I just machine down the underside center of the bucket
.1mm, as opposed to the old (bad) trick of lapping (grinding down) the end of
the valve stem. Not sure if you can lap the shim buckets (valve hats), but it
might be possible to machine them, at the risk of weakening them. Some people
grind a spot off the valve stem, as the valve will eventually have to be
replaced anyway. Hombre sin Nombre
- Consider Winkler Caps. Contact Team Pami's at their
Winkler Caps, item #65.
What do I do if the clearances are too small for available Shims?
- Try the shorter Length Valves of the two sizes. If you have the longer
ones in there.
- Get the Valve Seats Replaced if that is what is receding.
- Grind the Valve Stem (which weakens Hardened Ends, so is
NOT recommended) and replace them with Winkler Caps. (See above).
by Aleksander in Dubai 98ST
No valve clearance revisited: Last time I raised this problem, some of
you (Todd and Patrick come to mind) requested to be kept informed of the
situation and results. I've installed the 2.00mm shim, and still face clearance
less than 0.05mm on one intake valve. So I'm going in. But first, I have three
questions, and would be very pleased if you would review my procedure. This
procedure was built from extensive reading of the archives, the FAQs, and
Clymer. The discussion by Todd, Patrick, Mal, et. al. of Patrick's problem last
April was particularly helpful. As with Todd, there are no trained machinists
in this country (lots of untrained ones though), so this is particularly
uncomfortable for me (also, I'm new to mechanics).
There are several possible causes of zero or negative clearance, and in the
tradition of checking the easiest ones first, here's what to do.
Cause A: The top spring retainer is interfering with valve closure.
1. Inspect underside of valve bucket (Clymer: valve lifter) and the top of the
spring retainer for sign of contact between these two parts. If there is any
sign of such contact, then the collet (Clymer: keepers) or spring retainer is
deformed or somehow not on the valve stem correctly. Only the valve stem is
supposed to be touched by the bucket. Possible solution: remove the collet,
turn the spring retainer a quarter or half turn, and reinstall the collet
rotated from it's original position to see if that makes it sit properly. Check
by reassembling, hand-cranking the engine a few turns and measure. Measure
again after running the engine a little, because a few hand-cranks doesn't
always make everything settle completely. If this doesn't improve the
situation, replace the guilty party.
2. Another way to check for the same problem is to compare clearances with and
without the spring [Mal#1011 25 May 2002]. Without the spring, the spring
retainer will not be pushed up into contact with the bucket, if indeed it is
making contact. Measure, remove the spring, reassemble, and remeasure. You will
have to manually push the valve into it's seat, which you *might* be able to do
without taking off the head, if you're good with a stiff piece of bent coat
hanger through the spark plug hole. Take care to not scratch the valve face
with the coat hanger. Different clearances means the retainer is interfering
with valve closure, hence the collet or retainer is deformed. Solution as
Cause B: Valve stem is stretched
3. Measure the valve stem (you have to take the head off to do this). Compare
with specification in the manual. Intakes should be 90.91 or 90.76, and
exhausts 90.65 or 90.05. If you've got a long one, you could try fitting a
short one. Do some math and measuring to see if you think this would help. If
the valve is longer than spec, then you need a new valve. You could lap the
existing valve stem or lap the bucket, but both are considered poor practice.
Cause C: Valve seat is worn, pitted, or settled.
4. Visually inspect for wear or pitting. Use machinists dye if you have it. You
can see if it is worn or pitted; there is nothing you can do to measure
settlement. Clymer describes another check: fill the manifold with solvent and
see if any leaks past the valve. If worn, "take it to a good machine shop that
does valve work and have them dress the seat of the offending valve. Taking
material off the seat will make the valve stick further though the head,
necessitating a smaller shim." [Flash 23 Apr 2002]. This solves one problem but
creates another, since if you're reading this, you are already at the smallest
size shim. You will need a shorter stem on your valve. If you've got the long
one, buy one that's shorter, or lap the one you've got, or lap the buckets.
Cause D: Valve face is worn (the bit that contacts the seat when
5. Inspect and resolve as above in C. The valve face can be lapped if wear is
What do I do if I have Zero Valve Clearance?
You CANNOT guess what thickness shims to put on the ones that are at ZERO, as you can't be sure the valves are completely closed at zero. You WILL need to put in thinner shims, then re-measure (to get a POSITIVE clearance to measure). My experience with re-torqueing the head showed that it changed the clearances slightly (as much as 2 shim sizes, in one case). I suspect that with installing a new head gasket and THEN re-torqueing it, you may experience that much or more difference - so it may be a waste to try to pre-determine the shims you will need (YMMV). Also, an oil film trapped between the shim and bucket can reduce the clearance slightly, until squeezed out (rotate the engine by hand several times before measuring the new shims). Marty #436
Consequences of Zero Valve Clearance
- TIGHT valves (small clearance)
are open longer and the motor breathes better and makes more power but the
valves don't last as long.
- LOOSE valves (lots of
clearance) are closed longer, run cooler (due to ability to transfer heat to
head), last longer but don't make quite as much power.
There may have been some consequences of riding with zero or negative
clearance, and these deserve attention. You should do the following inspections
even if you solved your problem way up at Cause A (hence you have not yet had
to open the head; well, now you do).
- With no clearance, the valve does not seat, which is required for transfer
of heat from the valve to the liquid-cooled head. Your valve may be burned.
- The valve seat may be burned, worn, or pitted from being exposed to
- The intake manifold and valve guide may have been exposed to combustion.
- The carburettor intake tubes are rubber, and may have been damaged. Inspect.
- If there is carbon build-up, note that after you've removed it, you will
have even less clearance.
- While you're in there, do all the measurements suggested in Clymer, to check
that all is in spec, and to serve as a baseline set of measurements if you ever
go in there again.
I can't tell you whether the clearance is
decreasing, since this is the first time I've done the check, and I'm pretty
sure BMW didn't do it at the 1000km check-up (they didn't do much of anything,
it seems, and they wouldn't have a record of that anyway). I'm down to 2.30mm
now, on both intakes, with clearance still less than 0.5mm, so I'll try
thinner. I have had a little backfiring previously. I thought that since the
original clearance was zero that the valves must not be closing, but I don't
know for sure; from what you say, sounds like they close (relief!). I'll be
checking every 5k km until the situation settles.
I can imagine (not being a mechanic, that's all
I can do!) that you are quite right about the degree of change, but it seems to
me that if .05 wouldn't fit, and after a .10 decrease in shim size it still
doesn't fit, that I must have been riding with zero clearance (unless there's
more springs in there than I know of). But with zero or less than zero, the
engine shouldn't run, since there shouldn't be compression, I think. Maybe I'll
get a horse ;-)
Comments by Todd #389
summary - I think you have a really good handle on what to expect. It's
expected/required that you'll need a valve spring compressor to remove the
springs and valves. Likely you can borrow or rent one. You may have to try
several to find one that fits well - when it fits right, it's quick and easy.
(Sometimes to get one that fits right, I've popped things apart on the rental
store counter, paid for an hour, and gone on my way.) Keep track of which part
comes from where! I suspect that once you have the valves apart, and/or can
measure them, the wear area will be obvious. So far I think you have a good
plan. This will make good information.
still have several .05mm shim increments available to you, probably plenty of
miles in that, so I wouldn't take anything apart until you have to. Unless you
want to! Please let us know what you find :-) . When you run out of thin enough
shims, you have to figure out the next step, probably looking at valve work. If
you still have no clearance to you ~may~ be able to estimate the shims you will
need by measuring the space between the cam and the shim bucket with the shim
- I'm not
sure exactly what the failure might be. The clearances ~might~ stop decreasing.
Since they seem likely to continue to decrease in the future, when forced to
choose a .05mm shim increment, I chose increased clearances. For example, I
chose to shim for a clearance of .175mm rather than 1.25mm. In theory this also
allows the valve to run a little cooler and wear a little less. This is usually
more applicable with hotter exhaust valves, but it's all I can suggest until we
know more. That, and I finally gave in to the synthetic oil hype and started
using it. Anything to NOT have to open the head. Once you get the valves right
you'll enjoy the performance increase!
- I agree with rakaD on the head gasket. If the
gasket were only a few days old and you had to take it apart again for some
reason, I'd consider reusing it, while keeping an eye on my coolant levels
for a few weeks, maybe going thru some gentle heating/cooling cycles to
reseat it. On a water cooled engine I'd never consider re-using a 4 year old
you run out of clearance completely, possibly either a valve hits the top of
the piston, making terrible noises, causing permanent damage (is the Rotax
"Zero Clearance"?) or eventually the bike stops running because the engine
loses compression due to the valve not closing. (Sometimes accompanied by
backfiring.) The fact that the bike still runs is a good sign. If you can use
thinner shims you are probably OK. You still have the problem why your
clearance deceases so much - if it keeps happening you will run out of shims.
I have the same problem on my '99, and will not know the cause until I run
out of thinner shims and take it apart. It's not likely to be valve seat
recession since we have hardened valve seats, but it might be valve wear,
valve stem stretch, or possibly valve collet (valve retainer) wear. If you
find out more please share it with us - this problem has been mentioned
before, but it is rare enough that we do not have a definitive answer yet. Or
at least not one that I know of.
cannot say I ever managed to gather enough data on the Classic valves to
really feel comfortable predicting valve clearances. And obviously, the GS
could be a bit different.....but let me throw some conflicting comments that
will confuse things further. :-) Skipping the whole debate of which set of
specs to use, or if BMW has issued ANOTHER secret change of specs: The Ex
valves seem to be either fairly constant or (in higher mileage engines) seem
to increase clearances, probably due to carbon build up. So you're probably
OK. (You already have some idea what your local gasoline does to engines.)
Then again, these engines run pretty lean and therefore hot, and wider
clearances are better for valve cooling. But we've heard of few (if any) Ex
valve failures. And changing it by .05 will take it close to the upper limit.
(Were those clearances tight/loose? Can you slide in a different clearance
made up of 2 or 3 thinner feeler gauges?) So I guess you can probably leave
the Ex alone, and next check they'll probably be at .27 and .28. If I had
comments from people on decreasing Ex clearance (like the Intakes sometimes
do), I'd go for the wider clearance. (Notice how much greater clearance the
GS is compared to the Classic - around twice the clearance compared to the
Classic.) OTOH, I've set ALL my valve clearances on my bike to the wider
clearances, even slightly wider than the range (since the specs for the
Classic are so tight, with only .05 increment shims). But I'd fully admit
that I am EXTREMELY conservative.
won't like my comments on the Intakes - considering that _IF_ they seem to
move a lot, (I think) they seem to decrease (especially in a few of the
Classics), I'd almost consider using 2.45 shims. I base this on the fact that
when the Intake clearances on my bike decreased slightly less than spec, my
engine response was noticeably affected, whereas slightly wider than spec
seemed to give good engine response. And the clearances seemed to decrease.
And the GS Intake clearances are SO small to begin with. Obviously we can't
really go comparing different engines here between carbs and FI, but I
suspect that the basic design criteria for the valves is similar between the
two engines. Modern valve trains with hardened seats and rims shouldn't wear
badly except under abuse.
love to see a database of valve data, but I doubt that even BMW has one.
How Critical is getting TDC exactly right?
- The fact is, you don't need to be EXACTLY on TDC for both cams to
check clearances. If you ARE, then you WILL be checking it correctly. The cam
is egg shaped. The "round end" of the cam, like an egg, has the same profile
for about 45 degrees of cam rotation. You can check timing on EITHER cam
through 90 degrees or so of cam rotation. But the timing for closed valves at
TDC, where the clearances must be checked if both in and out are to be checked
at once, is considerably less. Nevertheless 15 degrees or so of cam rotation (I
seem to recall) for an off-tooth, should still allow an inobservant mechanic to
check clearances. Of course if any of the shims HAD been changed at the last
service, I would suggest that you had paid good money to have a bad mechanic
screw up the timing on your bike. Yet another reason to do valve shim changes
yourself. Flash #412 (CO)
What causes changes in Valve Clearances?
- Typically clearances decrease due to valve seat/face recession. this
is erosion cause by high head, metal transfer, etc. once a valve clearance
tightens up to zero, it stops transferring heat across this boundary (cause the
valve never really touches the head/seat when "closed") and erodes much faster.
Clearances increase due to a number of issues, one obvious one is if you bend a
valve, and it can no longer fully close. Intakes don't usually bend, it's the
exhausts. This is because intake valves open as the piston drops, the exhausts
are open as the piston rises. Another reason a valve will loosen up is if you
switch a motor running and built for unleaded to a leaded race fuel. the build
up of lead on the seat prevents full closing (but not enough to prevent heat
transfer) and increases clearance. I suppose if a valve became carboned up
enough, it could also exhibit this behavior. mtiberio (cugino pegaso).
- Other causes are: Valve
train wear and slop, tappet/adjuster movement (not really applicable to the F),
cam lobe wear, valve stem stretching, and the more common carbon build-up (not
usually too common a problem with the lean burning F, unless it burns oil or is
running rich). Todd #389.
What size are the Valve Shim's. Do I have to buy them from BMW?
- Valve shims measure 1.142" (with
callipers) which is close enough to 29 mm. I'm told that some Kawasaki's and
modern Triumphs use the same diameter shims. Flash #412.
- They are 1.141" Pooshkin
- They're 29mm. Same as some/many Yamaha shims. Bryan #179 (NM)
- Same as the early two valve Kawasaki shims. I think the Suzuki's are
different. mike410 (Iowa)
- While it is a non-acknowledged fact, the shims (diameters etc.) for
the F650 are the same as the ones used for BMW cars. The dealer will have them
for you, you may have to tell him to look them up in the automobile section of
the EPC though. Jim
- The thinnest that I know of are 2.0mm.
- Also try ATV dealers for Bomberdier DS650 (pre 2007 models) - they use the same engine and the 29mm shims.
- The KLR 650 uses the same shims. Check the following website: http://www.dual-star.com/index2/Brand/Kawasaki/klr%20650%20valve%20shims.htm
- If anyone has non-BMW sources for the 2004-onwards (shim under bucket) shims, please let us know.
What's the story with that TDC Bolt?
Looking at the picture with the valve cover off, what am I measuring?
(i.e. where are the clearances into which I have to insert the feeler gauge?)
- The feeler gauge goes between the Cam (those egg shaped things) and
the shim, which is right underneath the Cam and is about the size of a
When I took the Valve Cover off to Check my Shims I noticed the Marks
never lined up
- ...like in this Photo, courtesy of Jim Powell: What's with THAT?
- Well if you want to do it without taking off the Cam Carrier
you need to get enough slack in the Chain. i.e. remove the Large Tensioner Bolt.
Don't let the Cylinder in there drop on the floor when you pull the chain. You
don't want score marks on it.. Remove it first and put it on a nice soft cloth
where it won't roll onto concrete etc. ALSO remove the FRONT Cam Chain Guide,
(The long Black Plastic Things front of the Chain) it'll give you bit more
slack. The front one just pulls out, pull it gently, when you reinsert it later
keep the bottom end against the front (metal) face of the Cam Chain Chamber and
it'll pop back in the slot. The rear cam chain guide rail has
a bolt stuck through it at the bottom and will NOT pull out. If you don't
have enough slack by removing the tensioner bolt and the front tensioner rail,
just pull the cam carrier blocks like when you change shims. Make SURE
the TDC bolt is in place so you don't go out (Timing-wise) to the Cam
Chain Drive at the Crank end.
What else can I do while I'm "in there"?
- You might also consider, if your bike is
weeping a bit of Oil from the Head Gasket and out of warranty, re-torqueing the
Head Bolts. while you have the Cam Carrier off. The Torque Sequence is here: Refer the
Head Gasket Replacement FAQ for some
further information. Shank.
How long are the Valves?
- The valve lengths listed in the Service Manual for the Classic F650
(non-GS) are: Intake 90.91 or 90.76mm and Exhaust 90.65 or 90.05mm. Todd #389
- All the IN are 90.93 mm EX are 90.68 mm long. Unknown.
- I have 4 inlet and they all measure 90.805, 4 exhaust 90.678. Mal
#1011, BB1 (not an F650, but same Rotax Engine.)
How thick are the Shim Buckets?
- My micrometer and dial calipers are standard, not metric. Here are
the measurements for a shim bucket, in inches, give or take a few thousandths
of an inch. (The numbers in parenthesis are the closest rational conversions.)
These were made with calipers on ONE bucket:
O.D. = 1.319" (33.5 mm)
I.D. at shim = 1.140" (29 mm)
Height overall = 1.029" (26 mm)
Depth of shim depression = 0.078" (2 mm)
I didn't measure the I.D. where it goes over the spring. C'est la vie.
I measured the thickness between the where the valve tip hits and the shim
depression, using a micrometer, on all four buckets and got:
(Looks like 2.5mm, nominally.)
Perhaps you noticed on page six of the latest (April '02) Sprockets that the
Ratay's had an experience with valve collets wearing, "causing the top of the
valve to sink dramatically, leaving very little gap in the clearance." Have you
EVER heard of collets wearing? They're a taper fit and do not move. The only
way I can think that they would "wear" would be if they were too soft and
simply got "hammered" (forged) to alter their shape. And THAT is a scary
thought. Flash #412
Why would my Valve Stems be a Weird length or My Valve Clearances be really out?
by Mal #1011 & Todd #389
- >Move your collets around a little and see if you get different
clearance measurements. Is there any sign of the ridges being distorted. Check
for the collets distorting to allow the collars to sit further up the valve.
This would allow the collar to contact the bucket instead of the valve. Look at
the buckets for signs of contact. Are they are a dull colour?
- Check for Laps at the Valve ends, where someone's added on a little
Bit. Here's Patrick's BB1 (Same Rotax Engine as the F650).
- The areas to look at are the valves "pocketing" worn
seats in the head or the valves.
- Check the Valve Lengths, stretching at the valve stems, can be fixed by
replacing the valves.
- There are NO caps on the valves and the cut away view in the shop
manual shows that the Collar/retainer is very close to the bucket but should
not make contact with it.
- I would check the clearance by putting the valve in the head fitting
the bucket/shim and cams and check the clearance without the springs as against
- In SPROCKETS I just got on page 6 "Little Engine" It
says " of note, one set of collets (attaching valve to spring) were
worn, causing the top of the valve to sink dramatically, leaving very
little gap in the clearance.". The only way this can happen is
with the collar moving away from the head, relative to the valve stem and
pushing against the bucket The bucket would then be in contact with the collar
instead of the valve. Giving the impression of the valve "stretching". I would
check the clearance by putting the valve in the head fitting the bucket/shim
and cams and check the clearance without the springs as against with. The
collets should be checked or better still replaced.
- If you do have caps at the end of your valves, Team Pami may have
done the work. Check Item #65 here:
Products and Service.
Photo below. If installed, the Winkler caps are there by design to prevent the
valve stem from damage, as the original stems were probably shortened (ground
I see pitting on my Exhaust lobes. Is this going to be a problem?
- One of the lobes of my exhaust cam is starting to pit, at just shy of
24,000 miles. I'm thinking I will probably need to replace the cam at the 30k
service. That pretty much sucks, given today's materials and lubricants. I
could understand if this was an Enfield or something from China. But it isn't.
- Cam Wear. 97 F650 ST. I got it with 6500 mi. on it, now has 8300.
Just checked valve clearances, OK. Exhaust cams show wear on tips and some
scuff marks on heel. Asked dealer they say this is normal. Intakes look fine.
- Next time
you're in there, measure the cams to see if they're still in spec. Clymer
says the wear limit is 39.7mm. Also, take apart the cams and look inside at
the bearing surfaces for wear, and measure them if you can. Get plastigage
before you open, though. My bearing surfaces are worn and scratched a bit,
but still in spec. Post if you find out anything.
Why did the measurement on both my intake valve change, when I only adjuste the exhaust shim?
- The only thing I
did was take out the intake shim and measure it, since this is first
adjustment. Yes I am sure the measurement was correct. After I put everything
back together I removed TDC bolt and rotated engine at least five times.
- When you removed the shims to measure them, you disturbed the
existing oil film. Flash 412
- Was the engine warm when you made the initial measurement? If so
that's your answer.
Are my Valves Sticking?
- I have
recently bought a F650GS from a friend and a couple weeks after I bought it the
engine would cease running when I left off the throttle even at 70mph on the
freeway. The bike would do this intermittently and after having it at the shop
for a week the diagnosis is the valves were sticking causing too much
friction for the engine to run due to them not being adjusted by BMW of San
Diego at the last service 500 miles ago as they were supposed to have done. The
bike now has 7300 miles on it and the shop I am having the work done at is BMW
of Hollywood. I am wondering if it is possible that there has been any
permanent damage since I am planning on taking the bike out into the wilderness
and do not want to get stuck because the engine has seized.
- Short Answer: Rubbish.
See Surging Stalling Basics
if it is a GS.
See also the Hard Starting Poor Running FAQ
Electrical Misc FAQs
Electrical Misc Qs GS
- It is just about impossible for the valves to be
sticking because of a missed valve adjustment. How valves could be sticking
(i.e. seizing in the valve guides) on an engine with this low mileage I can't
imagine. I do not understand this assessment at all. I would get a second
opinion at another shop. echo
- I am assuming that this is NOT being covered under
warranty. Look for a second opinion, probably best at the dealer that neglected
the initial valve adjustment (to fix it, just in case). With that complicated
fuel injection system, MANY electrical gremlins could also cause intermittent
issues. Marty #436-Chicago-97 F650F
- If the valves were too tight, the engine would not
idle, but would run OK at higher engine speeds. (I know, I had a bike that was
serviced by a dealer who adjusted all of the valves in a Suzuki engine to have
zero clearance when cold - another reason why I do most of my own servicing.)
Valves to not "stick" in motorcycle engines. If they stuck they would break not slow the engine down. Richard #230
What's happening to other People's Valves?
from Chris in Santa Cruz, CA #782
- Here's the FAQ valve data in mm's:
on 9/30/00 with 8,500 miles
L Ex started at .127 loose ended .127 loose
R Ex started at .150 firm ended .150 firm
L In started at .100 firm ended .100 firm
R In started at .090 firm ended .140 firm
on 5/28/01 with 14,200 miles no changes
L Ex .127 loose, .152 no go
R Ex .127 loose, .152 no go
L In .127 firm, .152 no go
R In .102 loose, .127 no go
on 5/23/02 with 18,800 no changes yet
L Ex .127 loose, .152 no go
R Ex .152 loose, .178 no go
L In .152 firm, .178 no go
R In .127 firm, .152 no go
I am going to wait until the next 6000 mile service before deciding to change
I'm at near 20000 and no changes in mine yet from new! I imagine the older the
bike gets, the less chance of having to do it, as the things surely are set in
by now. I will continue my checks, but not expecting any change.
exhaust=.09mm front right exhaust=.178mm
rear left intake=.127mm rear right intake=.166mm
(Sorry not very useful!)
These are the measures
of the valve clearances and my conclusions. Not terrible for 20K miles without
LEx: .102 Ok .127 No In Specs
REx: .076 Ok .102 No New shim must be 0.05 thinner (.126 Ok .152 No)
LIn: .063 Ok .076 No New shim must be 0.10 thinner (.113 Ok .126 No)
RIn: .102 Ok .127 No In Specs Thanks G. '97 F650, Waltham, MA.
Anybody actually replace shims during 6,000 mi check-up?
spoke with my BMW dealer about getting parts to do the valve check at 6,000
miles (i.e., crush washers). He said they had the parts, but that it is highly
unlikely I really need to check the clearances at 6,000 miles. Dealer says to
skip it. Said the valves on the newer 650 engine will not need adjusting until
12k miles, and that to simply check them now is a waste of money (if he does it
for me) and definitely a waste of my time if I do it. My mechanic said he has
yet to see a F.I. F650 engine out of spec at 6,000 miles. Said they would
support me with any potential warranty issues. What has been the CG experience
with this? What direction does the gap normally go with wear and tear: wider
(noisy) or tighter (bad)? My dealer mechanic told me the gap would get smaller
with wear, normally. This is why it will become hard to turn over when it gets
too tight, especially when warmed up. If the mixture is rich, then some fouling
will occur that will cause a wider gap. Scott, ID #1244
Generally intakes tighten and exhausts loosen over time.
- I was planning on
starting a new thread but...this seems like an appropriate place to post about
my valve checking experience just minutes ago. I was really hoping to just be
checking my valves and not making any adjustments to my '03 CS w/ 6400 miles. My
smallest feeler gauge, 0.038 mm, does NOT fit on the left-hand intake side. It
barely fit under the right-side intake lobe. On the exhaust side, I could get a
0.254mm feeler under both sides. The next size up, 0.279mm, fit the right-hand
side but not the left. Unfortunately I am out of time and do not have a
micrometer or TDC bolt. In my case, checking valve clearances at 6k was NOT a
waste of time. Is there any reason why the clearances were tighter for both of
the left-hand valves? haven't had any problems starting. It hasn't been
warm lately, but I didn't have any problems all last summer. *knock on wood* it
fires up every time without turning over much at all, even after 3 months of
winter storage. wicked94pgt F650CS Natick, MA
- I have a '98 F650 and
needed to replace one shim at 6k miles. And no, if you err on tolerance you want
to err on the loose side, the larger gap. Part of the issue with valve lash is
how long the valves, particularly the two exhaust valves, sit against the head
where the heat they've absorbed runs off into the head. Obviously, the larger
the gap the longer the valve stays closed. Otherwise they may warp. From past
discussions about this on this forum I don't think it's unusual to have to
adjust at 6k miles and I certainly would check and adjust as necessary. '98
F650, Bellingham, WA. Johnny #862
- "If you err on
tolerance you want to err on the loose side.....Obviously, the larger the gap
the longer the valve stays closed" Up until the point the the valves don't allow
enough charge in or exhaust out. IIRC, too large a gap also causes increased
valve train wear. David#476, '99 F650, R60/5, K75RTA, Las Vegas.
- Just finished my 6000
mile check-up and the dealer had to go to a 2.35mm shim, as the measured
clearance was tighter than spec.....I think he had to change it by just 0.05mm.
I'm now at 0.10/0.10 intake (near the top of the 0.03-0.11 range) and 0.27/0.25
exhaust (near the bottom of the 0.25-0.33 range). Wish someone could tell me if
the intake clearance now being at the top of the range and the exhaust being at
the bottom of the range gives me more or less power or wear or reliability, etc.
'01 F650GS Dakar, Texas.
- Chris, IIRC someone
posted on the last valve adjustment thread that generally intakes tighten and
exhausts loosen over time, so what you have is good. I don't have my paperwork
here with me but I believe that is true in my case, the intakes have been under
and exhausts over. David#476, '99 F650, R60/5, K75RTA, Las Vegas.
- My 01 Dakar had two
valves that needed adjustment at the 600 mile service. My experience with non
BMW bikes with shimmed valves is that once set they hold their value for a long
time. My ST1100 with 91k miles on it has never had an adjustment. But I still
check it every 18k as the manual suggests. When my Dakar hits 6k you better
believe I'm going to check it. A tight exhaust valve will burn easily in that 6k
interval. '01 F650GS Dakar, New Jersey. echo
- I think it's the other
way around - unless I am not understanding the wording. The clearance on the
exhaust valves will tighten, requiring smaller shims. From section D of the F650
Classic "Valve Shim Check & Change FAQ": "Other Chain Gang members have been
told by their dealers loose is better than tight, as the clearances very often,
but not always, decrease as the valves seat with wear. It is advisable however,
not to wait another 6000 miles to check, or a burned (exhaust) valve may
result." Paul #1289, Red '99 F650ST, Southwestern Quebec.
- I replaced one at 6K,
none at 12K, none at 18 (one was close). I think I will have to replace one at
24K. Chris in Santa Cruz, CA
- Mine were replaced by
my dealer at the 600 mile service and the valve lash has remained static for the
past 30,000 miles. Richard #230 1997 Funduro.
- I had to replace one
shim that was 0.01 mm out of spec and chose replace the other three as they were
.05 mm away from the max gap allowed. All this at 7 k. 02 Dakar. The gap becomes
smaller with wear because the valve and valve seat wear out and seat further up
into the head, this allows the valve spring to push the shim bucket further up
closer to the cams. Too small a gap will prevent valves from fully closing and
thus increasing the risk of burnt valves, not to mention loss of compression,
etc. In a KLR that I bought used the shims had never been changed in almost 20k
(!) and the gap was zero. Still the bike ran fine and had no starting problems.
When I finally did change the shims I did not experience a truly better
performance. Juan '02 F650GS Dakar, '01 XR650R, Valle de Bravo, Mexico,
"Pavement is just a link between real roads".
- I have not had to
replace a shim in 80k. '97 F650 (over 80,000 miles), Indianapolis.
- My valves were within
spec at 6000, however I can't say how well within spec they were. I just put the
minimum shim in there and they fit, I put the maximum shim in and they didn't
fit. This was on a 2002 GS, done on March the 23, 2003. Oh yeah, this was at
6104 miles. Seacuke, #1214, F650GS, California, East of the Bay Area.
- I paid to have mine
checked at the 6K service and then checked them myself at 8K. Ended up replacing
two shims. They were still OK when I did the 12K check.
teddco, Augusta, GA 97 F650ST, 1998 ST1100, 2001 Hayabusa
- I have checked mine 3
times in 20,000 miles. No adjustment need. Valves well within specs. F650GS
Dakar, Oregon. Steve 1130 Or
- One of my exhaust
valves was +1 (mm?) @ 6K and no change @ 12K. Coming up on 18K next month. David
#476, '99 F650.
- My records are 1000
miles away from me at the moment. But I seem to recall that I changed at least
one shim at the 6k 12k, 18k, 24k and 30k services. A dealer telling you that it
is ok to skip the CHECK should be gotten in writing if you are seriously
considering it. If the dealer BELIEVES that it is ok, he should have no trouble
stating so in writing. Consider sending a copy of the document to BMWNA and ask
them what THEY think about it. Flash 412 (CO)
- IIRC one of my shims
was out at 6000 miles too, on my GS. Both Inlet Shims Changed to Bigger Shims
(Gap too Big.) I didn't get the Classic until after it had done 10,000 miles.
However, for those of you with Earlier bikes, this MAY be because the clearances
were re-specified by BMW. i.e. if the installed the Shims to the OLD clearances,
then issued a Correction to new clearances, the changes are more apparent than
for a newer model (See FAQ) Kristian#562
- I would not skip the
6k check and neither would I recommend skipping the 600 mile check I heard
described as unnecessary. F650GS Dakar, Camden, New Jersey. echo
- Should I be worried if
my gaps are too small at 6k? My smallest feeler, 0.038mm, would not fit under
the left intake lobe. Sure maybe a 0.030 might fit, but everyone else seems to
be getting gaps closer to 0.10mm. The 0.038 feeler fit on the right intake but
it was snug. On the exhaust side, I could get a 0.254mm feeler under both sides.
The next size up, 0.279mm, fit the right-hand side but not the left. Once again
my left gap is just within spec. Are the specs any different for the CS? btw we
have a parallel post going in the maintenance forum: valve adjustment
wicked94pgt BBG#22 F650CS, Natick, MA
- Checked all the time
but no adjustment needed (I am 90% sure) before about 40,000 miles. y_kiwi
Lance, #1303, '01 F650GS, '96 G650ST.
- Never needed any valve
adjustments, so far 26000 km (approx. 16200 miles) '00 F650 Dakar, Switzerland.
- I checked mine this
weekend at 8500km's and everything is in spec. The left exhaust was the slackest
at around .138mm. The others were between .12 and .13. I'll be checking them
again later this summer to see if that exhaust valve gets tighter or sloppier.
Paul #1289, Red '99 F650ST, Quebec. pbenven
What! No Valve Clearance?
- Ok, so I
finally finished getting moved into my new place and it was nice out here on
Sunday so I went to do some work on the bikes. I am doing the 12000 or whatever
service on the bike as well as the yearly. I managed to drop one of the tiny
springs from the gas cap into the tank, I am hoping I can get it out now that I
have drained the tank, I may end up taking out the fuel drain valve to get it
out. On the Valves I am now stumped, I have NO clearance on either intake valve,
the exhaust valves are perfect. What I am confused about is aren't the clearance
supposed to get larger with wear? I read over the FAQ's but it sounds like those
bikes have many more miles on them, mine only has 18,000. I guess what I will do
next is take out the shim and see how much room I have without it and if there
is room I will put a smaller shim in. Is it possible they sent out the bike from
the factory without proper clearance? I think I once read about someone who's
bike was like that. Ok, so here are my measurements, the Left Intake, which had
the only readable mark of Y240 is .0955 inches or 2.4257 mm (note that last
decimal is probably not valid). The right intake is .0948 or 2.4079. The left
exhaust is .0929 or 2.3597/ The right exhaust is .0948 or 2.4079. Thus it looks
like I had 3 2.40 shims and one 2.35 shim. So now if I take my measurements and
go from the 2.4079 shim to a 2.35 shim for the Right intake my clearance will be
.1339 which is in the range. For the left intake if I take the 2.4257 and go to
a 2.35 shim I will have a clearance of .1517 which is again in the range. So I
am going to get 2 2.35 shims. MasterITRIT #F650-1231 -- '98 F650 Classic -- '80
Yamaha XT250 -- Rochester, NY.
claiming that this is your problem, but I have read and heard of a phenomena
called valve seat regression, wherein the valve edge impacting the valve seat
works the valve seat metal like a small forge and reduces the valve seat
thickness a smidgen. The valve stem is now closer to the cam lobe by the amount
that the valve seat thickness was reduced. I don't think it continues
indefinitely. On the other hand, if your valves were "checked" by a BMW dealer
at the 6,000 mile service, that could be the "cause". I checked my valves at
8,000 miles, after a BMW service at 6,000, and had to re-shim 2 of 4 valves.
Have you tried fishing with a magnet for the spring in the gas tank? Teddco, 97
F650ST, 1998 ST1100, 2001 Hayabusa
- Do you
have a crank-stop bolt in place? Do the lines on your cams more or less line up
with the valve cover surface? Perhaps your intake cam is off a tooth. If your
crank and cams are not in the right place, you are not measuring what you think
you are. What you should do (after checking to make SURE that you have been
measuring with the intake cam with the line dead-parallel with the valve cover
surface) is pull out ALL of your shims and measure them. Keep everything
straight so you can get it back like it was. Put the smallest shims you have in
the intake valves, assuming that you have some smaller than what is in there.
Put the cams back in and rotate the engine through a couple or four revolutions
and measure again. If you don't have a shim small enough to get a measurement,
go buy one. Flash 412 (CO)
Bad Valve causing Starting Problems?
My wife has been
struggling with "Cold Starts" on her F650 and we tried just about everything
on the website. This Spring we took into the dealer and felt the problem was
the Fuel Enrichener (aka choke) or carb. They cleaned both....no luck the
problem still existed and we took it back in. 2 weeks ago we got a call from
the dealer. They did a "bleed -down" test on the cylinder and it did not meet
specifications, indicating something bad with the valves. They did a quick
look and thought an exhaust valve looked burned. A week later they did remove
the head and confirmed that 1 exhaust valve was burned and it need to be
replaced, which would resolve the starting problem. My 1st question...why
would a bad valve cause a cold-starting problem? Well I was educated. The
enrichener (choke) is not mechanical but vacuum operated. With the bad valve
the engine might not be creating enough vacuum to allow the choke to work
properly. Well I wasn't sure but said lets give it a go! This week the
mechanic called. Said the bike was back together and started easy, ran fine,
and seemed to gain a little power. The good news was that BMW decided to
warranty the parts, valves, gaskets etc. That saved a couple hundred. I asked
why a bad valve at 15,000 miles. Most likely a bad batch of soft valves in the
new bike. Last night week picked the bike up, it started fine, ran good, my
wife says it did feel a little "umph". Its only been one day but we are
encouraged. I would have never guessed a valve causing this kind of problem
might help others. Bob & Mary Beth Alexander (she's not a chain ganger yet but
soon) PS Judson Cycle in the Mankato, Minnesota area has been great in helping
on this one!
- As far as the
vacuum thing affecting starting, it's not directly choke related. Almost all
choke/enrichener methods (except direct fuel injection) need manifold vacuum
to work. Suck nothing into the cylinder, enrichener or choke or fuel mix
doesn't matter, no fuel mix to fire. And a burnt valve not sealing affects
both the engine vacuum and compression. If it's badly burnt there's no vacuum
to suck in the fuel/air mix.
Of course you most notice the compression/vacuum problem WHEN THE ENGINE WON'T
START! After that, if it will fire a few times, even a few misfires, sometimes
the heat/detonation/pressure will be enough to get the valve to seat well
enough to run. After that, you don't notice the problem again UNTIL THE ENGINE
In a multi cylinder engine, you can last a long time with a burnt valve, as
the other cylinders still run. Can't fake it with a single! So the problem was
really that there was a burnt valve affecting engine compression/vacuum,
preventing it from starting, not really that the burnt valve affected the
choke/enrichener function. And that point could be in the Hard Starting FAQ's.
So also could "out of gas", "missing spark plug" and "broken crankshaft". :-)
Hard Starting / Power Loss After Shim Change?
- If you experience problems starting your bike after a valve shim change, you have most likely got the timing off by one or more teeth. Take everything apart again, and find TDC. Check your timing marks are parallel to the head. The TDC bolt is suggested for this very reason.
- You may experience minor power loss if you have changed your shims.
- Did you put the throttle cable back in the correct slot on the throttle body?
The BMW Video States the timing should be off by a half tooth?
- This is incorrect. Please read the other Valve Shim Check/Change FAQs, and watch the Chain Gang DVDs. The timing marks should be parallel to the head with the cam lobes pointing outwards.
Can I use a magnet to get the shim out?
- I am not so sure I would use a magnet on a shim......IF you reuse the shim it may have become slightly magnetised and attract some suspended metal residue from the oil (that the magnet drain plug does not catch) and cause later grief etc. IMHO jack #1977
Any hints on removing the intake cam?
- Here's a confirmation on removing the cams without taking off the chain tentioner bolt on an ABS bike. I was able to remove the intake valve easily using this proceedure:
- Pull on the cam chain to bring all the slack to the top
- Use a 2mm allen wrench (or something with the same size) to lift the intake cam up from its slot as shown in the picture below (yellow circle). Note that you don't need to lift it all the way out but just a couple mm up. Be very gentle, as it requires very little force.
- Now insert the allen wrench into the front side of the same slit (green circle) to lift the cam out completely with, again, very little force.
- See this image
How important is temperature when doing the valve clearance check?
- Is it possible to do a valve check at 5 degrees centigrade? I don't suppose the shims, feeler gauge etc would contract to an equal degree or that the metal shrinkage factor is neglible at 5C?? I know the clearances are very small - I'm guessing I might need 20C? Unfortunately my garage is of the wooden, 60+ year old variety and my climate is of the chilly Canadian variety. The bike is of the 60,000km classic variety. Johnny Canada #1088
- Don't worry about it. It will be really close. jetdocs550 #1546
- Coefficient of linear expansion for various steel formulas range from 10 to 12 parts per million per degree celsius.
To put this in perspective, a 2 mm thick shim would contract:
2mm x 12parts x 100 degrees
or about .0024 mm with a 100 degree celsius drop in temperature. Me thinks you are safe.
You're biggest risk at below freezing is getting water vapor from your breath condensing and freezing on the shim as you measure it, and the feeler gauge would then show things tighter than they really are. TexasArmadillo
Solid Cam Chain Tensioner?
- Has anyone seen this site: www.rotax.net? They have a solid cam chain tensioner for the Rotax F650. Does any one know if they are any good. The site boasts: 'Replaces the stock hydraulic cam chain tensioner and gives more consistent cam timing. Required for high lift cams and high RPM applications.' - dnd, Brisbane Australia
- I guess if your cam tensioner breaks in the middle of nowhere, you can use that concept to have a local fab one for you. Drill and tap a hole in the "plug," stick a piece of a bolt in the hole and use a bolt and locknut through the tapped hole to adjust it. Woo HOO! Flash 412 (CO)
Should I use a Torque Wrench?
- When putting everything back together, should I use a torque wrench?
- Personally, I wouldn't even THINK of putting hardened steel bolts into an aluminum engine/cylinder head WITHOUT a proper torque wrench. You may as well dump a handful of sand in there while you're at it. I'm sure there are a torque spec, I use a torque wrench. dlearl
- If you are an experienced mechanic, you should be able to make your own informed decision. If you are a beginner, a decent quality torque wrench may save you a lot of pain if you get something wrong. Winter #1935
- Note: Some well known members of the Chain Gang have used a torque wrench, but with the wrong settings. Make sure if you do use a torque wrench you use the correct setting. If your brain starts niggling you saying "this is too tight", stop and check your torque values!
Why do I turn the crankshaft clockwise?