Exhaust Gasket/Exhaust Nuts Replacement FAQ.

Compiled by Kristian #562. Pictures by Kristian #562.
Please read the Disclaimer before attempting any work in this FAQ.

Note. This might sound really dumb, but do please wait for the bike to cool completely before replacing any Gaskets.!


Classic Exhaust Gaskets

Where are all these Gaskets ?

There are actually a total of FOUR Exhaust Gaskets on the Stock Exhaust Pipe, (Only three for a Staintune) however the most common ones that fail are the two at the Engine/Header pipe connection.

They are:

If the leak is right at the exhaust header, where it connects to the engine, the leak could cause valve damage over a period of time, if it is anywhere else further down the exhaust system, it will just make noise. 

Gaskets Replacement at the Cylinder Head

By Shank, Flash #412

December ‘01


What to check First: Before you go replacing the Gasket, try first tightening the nuts that clamp the Exhaust Headers to the Engine Ports. The location of these nuts is shown below. Replacing the gaskets should give you far less flatulence (wish I could say the same for me), will be quieter and may give you more power. Check also you actually have the nuts, as sometimes they can come off.


  1. Symptoms of a Failed Exhaust Gasket:

    As you increase revs you may get popping and perhaps in a darkened garage or at night a blue flame shooting out of a pipe on the front of the engine around the exhaust pipes. The flame if any will come from around the clamp. It may not have been assembled correctly at the Factory, or it might just have got tired.


    1. It can also make it LOOK like a weeping head gasket, because of the spooge that comes out, so don’t go replacing your head Gasket Until you’re sure.!

    2. Also, this junction is right below the temp sensor that turns on the fan. The hot air blowing out of there Can heat up the thermostat and fan sensor, turning the fan on prematurely. And when the fan comes on, it will blow the hot exhaust gasses on your leg.

    3. My 98 F650 appears to display defective behavior. The symptoms are as fallows: an unusual, gargle sound after downshifting (after clutch release), rapid acceleration or rapid deceleration, the sound appears to originate and/or surface in the exhaust. I have also noticed a slight decrease in overall power performance. Jacek.

    Refer also the Backfiring FAQ and the Strange Noises FAQ for more Symptoms of a Failed Exhaust Gasket.

  2. Where are the Clamp Nuts:

    VERY often you can fix the problem by simply tightening the Exhaust Header/Cylinder Clamp Nuts. Do not overtighten! The nuts are as soft as cheese. Here is the RHS Upper One, RHS Lower one, LHS Lower One. You can also try tightening the Exhaust/Collector Clamp. If you need to replace the studs, refer What about those Rusty Exhaust Nuts below.

  3. So how do I test if they are leaking:


    You can check these with a bit of smoke (like from a cigarette) in a still area, wafting around the joints. Headers also crack and split sometimes. Watch for the smoke being blown away by leaking exhaust gases.




    Take an old, tired dollar bill (which is very flexible) and wave it around in the vicinity of ALL of the Exhaust Joints to check for leaks.


    Is there a Temporary Fix so I don’t wake up the Neighbours coming Home.?


    Stuff the offending hole with aluminium foil and lo, the whole thing will be quieter, fart less (wish I could do the same) and the fan won’t come on as often.


  4. So how do I fix it properly.? 

    OK, lets do a little naming, for clarity. Assuming:


    Lex = Left Exhaust

    Rex = Right Exhaust

    #8 = Exhaust Gaskets at the Head. This has been reported as a corrugated sleeve that fails under the clamp. The Replacement gasket is no longer corrugated.

    #5 = Gasket between Tail pipe and Mid-pipe

    #7 = Gasket between Lex head pipe and mid-pipe

    The numbers will make sense if you have le partsfiche a l'i'clair.

    (That’s the Parts gif, for Details refer Documentation). (or Shh, don't tell BMW. Exhaust gif)


    Note: You can get sockets on Rex. You CANNOT get sockets on Lex.

  5. Gasp.! I'm sure there is no gasket there.!

    There is. Stick your finger in the port. Feel for the EDGE of the gasket as your draw your finger out. You might need to feel in several places (3 o'clock, 6, 9 and 12 for instance). If you go ahead and put a new Gasket in on top of your old one i.e. TWO gaskets in, your exhaust system is more liable to leak and won't fit exactly right. Besides that, the nuts won't run down as far.

    The gasket where the U-pipe joins the collector is just asbestos (or some sort of impregnated carbon) as is the gasket where the collector joins the muffler. With NO metal, these can disappear gradually. The gaskets where the pipes enter the heads have METAL in them. They cannot disappear. When I first took my header pipes off, I thought those gaskets were missing, too. Keep looking.

  6. Gasp#2. I think I was given the wrong-sized Exhaust Header Gaskets

    Sound Familiar?
    Does the F650 have different size gaskets to go between the exhaust pipes and head? (I'm thinking of certain models of BMW Airheads that had different sized exhaust pipes) Reason I am asking is that I was installing new ones to replace the old ones (OK at 25K miles) while the muffler was off...and the new ones were 1-2 mm too big in diameter to fit into the bores in the head. As they are soft "crushable" material, I "made them fit", but as they are calling for snow this week (and likely the season's first de-icing salt), I probably won't know until next spring if they actually seal or not. Marty #436.

    Actually I had the same problem. Kristian #562. I MADE them fit, which is why in this close-up of one of them, it looks all squashed. Don't know WHY BMW do that. But it looks like it's normal. You might have more luck with a set of Gaskets from Aprilia (The Pegaso Gaskets will fit the Classic).

  7. If you need to replace the studs, refer What about those Rusty Exhaust Nuts below, otherwise.

  8. Reassemble: In reverse order.

    It REALLY helps to have someone over on the left side, feeding the left pipe into the head while you're dealing with the other three joints all at once on the right side
    Tighten it all up.
    Torques are in the Torque Table.
    Fire it up.

    Test again as above.

  9. Notes: Justin843, Flash #412.

  1. There is no way to get socket wrench or torque wrench on the main exhaust pipe nuts without removing the radiator. The tool to use is a 13mm box end wrench. You won't have to mess with the radiator and it works quite well.

  2. Get the collector pipe flare pieces to open up to accept the new gasket is not easy with all the other hardware getting in the way. You have to pull the pipe flares open with a pair of pliers, but getting a bead on it is tough. I just pulled the lowest one open as much as possible because there were no obstructions. Another method is to stick a long screwdriver in the slot between the "ears," angled from the inside of the hole, as close to the open end as you can get it and then smack it with a hammer.

  3. If your think your main exhaust gaskets have disappeared... you will swear on your mother's grave you have no exhaust gaskets. They are there, really.

  4. Collector gasket = $11 clams. They wear out quickly They wear out quickly WHEN THEY START TO GO. But if the clamp is tight, that isn't a problem. This is NOT a normal wear item.

  5. Exhaust gasket= $1.50 - that's a BMW shock! They are durable. I think you can probably get the same gasket at lots of other motorcycle stores for half as much. But I do not KNOW this.

Gasket Replacement at the Collector/Header Pipe Junction

by  Francois
December ‘01


My exhaust collector/header pipe gasket (end of the U tube) went (99F650, 26,000km) and was leaking gas.


I am not happy about the lifespan of this piece which is way too short, and I am especially unhappy about BMW’s explanation that it was destroyed by an excess of heat! I thought this piece would be designed for this.


The Symptoms were:

Part Number

The Gasket Dimensions are:



Removal of the old Gasket is fairly easy: 

As advised by the mechanic, I left about 2 mm from maximum tightening of the clamp.




Start the engine and check for leaks, as per the procedure for the Gaskets at the Cylinder Head. 

The whole thing is quite easy and takes less than an hour, you just need two Allen keys from the bike tool-set, pliers and a 13mm wrench.
The bike now sounds fine, power is back and there is no backfiring.

Mechanic’s advice:


Do not tighten the gasket fully straight off. Ride about 150 km, (the gasket will shrink a bit), then do a final tighten.
The clamp is specially designed so that it can’t be tightened to less than a certain minimum diameter.


On-the-road Alternatives:

What about the GS Exhaust Gasket?



Unlike the Classic, the GS has only ONE, Large Exhaust Gasket. At the present time there is no procedure to follow for its replacement, but is likely to be very similar to the Classic.


Meanwhile here is some feedback:


What about those Rusty Exhaust Nuts/Studs?

by Flash et al.

Q. I have a F650ST and I am concerned at the state of the exhaust studs that hold the exhaust to the cylinder head. They are looking a bit corroded. I am concerned that if I need to remove the exhaust in the future I might have some difficulty. Any advice on how to get around this problem would be appreciated. Skidmark.
A. Replace the studs now. Use ant-seize.

Q. Can you please advise how to remove the studs.
A. Pull whatever it is you need to pull to have access to the area. (See above). Remove the nuts. A clamp plate will pull out of the way. Shoot a little Liquid Wrench® around the base of the studs and follow the instructions on the container. Use Vise Grips® to twist the studs out. If you need to pull the headers to do the job, so be it. The absolute worst case is that you will break one (or more) off in the head and need to drill it to remove it. There is no point in using any Loc-Tite® on reassembly because of the temperature where the studs live. To screw in the new studs, put two exhaust nuts on one stud and jamb them together using two spanners. Then put the wrench on the outboard nut to "drive" the stud home in the head. Yes, hi-temp anti-seize on the threads where the nuts go, just before you install the nuts.

Preventative Maintenance:
1) Soak with WD-40
2) Remove one at a time. Clean with wire brush. Glop on anti-seize. Retorque.

Unless they look like the corrosion is more than surface, I wouldn't try to remove them unless they come out while trying to take the nut off. If one breaks, then what could have been a clean-up and re-lube job becomes a nightmare.

Alternative Gasket Sources?


Ring Gaskets

by Flash


You might have more luck with a set of Gaskets from Aprilia. (The Aprilia Pegaso Gaskets will fit the Classic).


Sleeve Gasket

by Steve F650001


I was in Eastern Oklahoma when things started getting loud. As I neared Queen Wilhemina State Park the loud got louder, and when I backed off the throttle the engine backfired. That may sound cool when you are 17 years old and driving your dad's vehicle, but not when you are the owner who has to pay for repairs. The gasket, a cylindrical woven "sleeve" that fits on the end of the left side exhaust pipe just before it enters the "Y," had disappeared, leaving quite a gap for exhaust gases. The closer a leak of that type is to the exhaust port the greater the chances for a burned valve. The connection is about 12 inches from the exhaust port.



At first I thought it to be the ring gasket, which fits inside the port and several Inmates helped by calling dealerships in their hometowns. We planned to contact another Inmate who would be coming to the rally and could pick up the part and bring it to the rally. Meanwhile I drove to Mena looking for replacement parts. Closer inspection showed that the ring gasket was not the problem it was the exhaust pipe gasket. [See photo]. I raced back and forth across town in desperate haste. Finally, I tried the Yamaha shop. With the short section of exhaust I my hand, the wonderful woman behind the counter came to my rescue. The $20 part was just what I needed. Yamaha #4DN-14714-01; also indicated 863066.