81 GS450E Timing Camshaft issues

[Alexxxx]

So when resetting and reinstalling the CCT one day the cam chain slipped a bit and put my EX camshaft timing a bit off (Below parallel). The chain still had 18 pins between 2 arrow(EX) and 3 arrow(IN). When attempting to fix said timing i have removed the camshafts both EX and IN and tried to reinstall per manual at TDC on ignition plate but everytime, everytime i try to tighten down the EX camshaft into place it slips due to the pressure exerted on the L EX lob-shim(since its pointing downwardish, putting pressure on shim) . And therefore the EX camshaft is always below the parallel line of the engine. What the heck do i do to make this work? Please and thank you.

 

[Steve]

Are you sure you are using the correct mark on the crank (TDC)? It's easy to line up to the F mark, instead of the T.

Are you sure you are using the correct mark on the crank (#1 vs #2)?

.

 

[2BRacing]

So when resetting and reinstalling the CCT one day the cam chain slipped a bit and put my EX camshaft timing a bit off (Below parallel). The chain still had 18 pins between 2 arrow(EX) and 3 arrow(IN). When attempting to fix said timing i have removed the camshafts both EX and IN and tried to reinstall per manual at TDC on ignition plate but everytime, everytime i try to tighten down the EX camshaft into place it slips due to the pressure exerted on the L EX lob-shim(since its pointing downwardish, putting pressure on shim) . And therefore the EX camshaft is always below the parallel line of the engine. What the heck do i do to make this work? Please and thank you.

I am not familiar with the smaller displacement engines at all, but on the 850 engine, the factory service manual instructs you to clamp the EX cam down using a vicegrip (locking pliers). There is an opening in the front of the cylinder head where the vicegrip clamps into, holding the EX cam down firmly to overcome your problem of the lobe pushing against the shim and making the cam move.

There have been previous posts about this, and many people are horrified at the idea of clamping the EX cam down with a vicegrip, but there is even a photo of this procedure in the factory service manual for the 850 - not sure if smaller displacement engines will be the same, so I suggest you look in the factory service manual for your bike.

 

[Steve]

There have been previous posts about this, and many people are horrified at the idea of clamping the EX cam down with a vicegrip, but there is even a photo of this procedure in the factory service manual for the 850 - not sure if smaller displacement engines will be the same, so I suggest you look in the factory service manual for your bike.

Yep, it's shown for 8-valve engines: (this one happens to be the intake cam)

and also for 16-valve engines:

.

 

[Guest]

Clamping is unnecessary on the twins. The Ex cam is just slightly cocked upwards on installation and pulls down easily with the cam cap. This preloads the pull side of the chain but due to the 1:2 gearup won't move the crank.

 

[Alexxxx]

This is the only way i can get the camshaft EX caps on because it rotates. I think i might have to clamp it on the L EX side of the cam shaft due to the pressure the lobe pushes on the valve. I have ttried using the cam chain to hold it in place but that doesnt work.

 

[Nessism]

Sounds like you are off by one link. If you mark the cam sprocket and chain it will help you keep track of where you are at. If the hash mark is a smig high of the gasket surface that's okay and is due to a small amount of chain elongation with mileage. The mark shouldn't point below the gasket surface though.

 

[Bob6767]

More pressure

More pressure

So when resetting and reinstalling the CCT one day the cam chain slipped a bit and put my EX camshaft timing a bit off (Below parallel). The chain still had 18 pins between 2 arrow(EX) and 3 arrow(IN). When attempting to fix said timing i have removed the camshafts both EX and IN and tried to reinstall per manual at TDC on ignition plate but everytime, everytime i try to tighten down the EX camshaft into place it slips due to the pressure exerted on the L EX lob-shim(since its pointing downwardish, putting pressure on shim) . And therefore the EX camshaft is always below the parallel line of the engine. What the heck do i do to make this work? Please and thank you.

When the ex cam is correct the number one is pointing forward and the left ex lobe is applying pressure on the valve. At the point it will skip with only a tiny bit of slack so the best thing to do is hold the chain into the cam?s teeth and slowly back off of that valve. You can still count 18 posts from 2 to 3, you just have to be creative on aligning the 3 on the intake cam. Once you settle everything down do not turn the crank until you have the chain tensioner in place. Otherwise it?s back to square one.

 

[Alexxxx]

Success

Success

Sorry for the long over due update . Thanks everyone for their input, all helpful. I eventually ended up zip tying the cam chain to get exhaust cam and then subsequently zip tying the ex cam to the frame of the bike in corrrct TDC position (w the 1 facing forward and the #2 up, etc). Once everything was aligned exactly and tied down on the ex cam I evenly screwed the ex cam cams on, securing them to torque 7ft lbs. Then with everything still aligned & secured on the exhaust side, I installed the intake cam into alignment w the #3 pointing at the 18th pin , next I installed the IN cam caps and then I install the CCT L. After a final recheck of pins, TDC, etc I loosened the lock nut on the CCT to create tension then I undid the zip ties and tested the tensioner through manual rotation of engine. And the timing has been perfect ever sense.

 

[tom203]

Zipties,vicegrips - sounds good,thanks for update!

On the tensioner,did you remember to back off the lock screw 3/4 turn and tighten the lock nut to hold it there?

 

[Steve]

Zipties,vicegrips - sounds good,thanks for update!

On the tensioner,did you remember to back off the lock screw 3/4 turn and tighten the lock nut to hold it there?

Please don't back it off 3/4 turn. ray:

All of the tensioners I have experienced would release the plunger far enough that it could be removed from the housing when the set screw was backed out 3/4 turn.

Backing it off 1/4 to 1/2 turn is plenty. :encouragement:

.