Counter-Shaft (c/s) Seal FAQ (2nd Draft)

compiled & edited by Kristian #562
by Flash #412 & Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.
June '02



What is the Countershaft Seal and Where is it.?


It's just a normal Oil Seal which seals the Engine Oil (Gearbox) from coming out past the Countershaft, which is the Shaft, with splines, that your small front Sprocket is mounted on. 


What are the Symptoms of Seal Failure.?


Oil Dripping down from underneath your sprocket and getting all over the bottom of your bike and around the c/s Sprocket area. Very messy. When you get the Sprocket off it might look like this:



Part Numbers & Tools:

You will need:


Torx Keys or Allen Keys in your Toolkit for loosening Chain Adjustors & removing the Plastic Sprocket Cover Plate
Sockets/Spanners for Rear Wheel Axle Slackening.

30mm Socket for the Counter Shaft NUT, preferably using a LONG handled Wrench.

Torque Wrench to 100Nm.

A Small drill, hand operated is MUCH preferred, you can control it much better than an electric one, and it is not slow if you have a good drill bit.

One or Two Sheet Metal Screws.


Countershaft Seal Replacement

It should be no big deal to replace the countershaft seal.

          The whole c/s Sprocket will try and turn if is not held by something, so to stop it turning you can either:

  1. Put the bike IN 1st GEAR. This will hold it via the Engine Resistance. This is easiest and should work most of the time.

  2. Place one foot on the Rear Brake to hold the Rear Wheel in place. (You can also put it in gear AND stand on the Rear Brake.!).

  3. Follow the Manual and unscrew the Plastic Centre Plug in the RHS Engine (Alternator) Housing, insert an Allen-Key Socket into the CRANK which sticks THROUGH the flywheel and hold the Wrench while you undo the nut. It doesn't NEED to be a socket. A standard Allen and piece of pipe will do just fine, as long is it isn't the weak tool from the stock toolkit.

  4. You can also use the (TDC) crank-stop bolt if it is in gear and not muck with the brake at all, if you happen to have a crank stop bolt handy. It's a small bolt BUT, it hardly sticks through the case at all before it goes into the slit in the crank. Here's a picture of the split cases and how the bolt stops the crank. Besides that, when you reef on the c/s nut, you have mechanical disadvantage through the transmission to the crank. In first gear, you have the INVERSE of the advantage the motor has over the rear wheel (less the c/s - final drive ratio). So 100 Nm is reduced by a factor of 7 or something, which means you really aren't reefing on the crank stop bolt. When you take the clutch basket out, that nut is nearly at the same torque. And the ONLY way to stop the crank then is via the crank stop bolt. Again, you have the disadvantage of the primary drive gear ratio in your "favor" (to keep from snapping the bolt).