F650 Valve Misc FAQ

compiled & edited by Kristian #562
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Last Updated: 16 Feb 2007, by Winter #1935

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What do I do if the clearances are too big for available Shims?

What do I do if the clearances are too small for available Shims?

What do I do if I have Zero Valve Clearance?

Consequences of Zero Valve Clearance


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).

  1. 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. Inspect.
  2. The valve seat may be burned, worn, or pitted from being exposed to combustion. Inspect.
  3. The intake manifold and valve guide may have been exposed to combustion. Inspect.
  4. The carburettor intake tubes are rubber, and may have been damaged. Inspect.
  5. If there is carbon build-up, note that after you've removed it, you will have even less clearance.
  6. 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

How Critical is getting TDC exactly right?

What causes changes in Valve Clearances?

What size are the Valve Shim's. Do I have to buy them from BMW?

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?)

When I took the Valve Cover off to Check my Shims I noticed the Marks never lined up

What else can I do while I'm "in there"?

How long are the Valves?

How thick are the Shim Buckets?

Why would my Valve Stems be a Weird length or My Valve Clearances be really out?

by Mal #1011 & Todd #389

I see pitting on my Exhaust lobes. Is this going to be a problem?

Why did the measurement on both my intake valve change, when I only adjuste the exhaust shim?

Are my Valves Sticking?

What's happening to other People's Valves?

from Chris in Santa Cruz, CA #782

Anybody actually replace shims during 6,000 mi check-up?

Question: Just 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.

What! No Valve Clearance?

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!

Hard Starting / Power Loss After Shim Change?

The BMW Video States the timing should be off by a half tooth?

Can I use a magnet to get the shim out?

Any hints on removing the intake cam?

How important is temperature when doing the valve clearance check?

Solid Cam Chain Tensioner?

Should I use a Torque Wrench?

Why do I turn the crankshaft clockwise?