Changing the CCT (Cam Chain Tensioner)

HaulinAshe · Jul 6, 2010

As it sometimes happens, this thread evolved into a confusing mess. That precipitated me to start a new thread with basic information that will hopefully remain clear. ADMIN NOTE: Off-topic and distracting material may be removed.

[SIZE=14pt]*** ANYONE CONSIDERING CHANGING THEIR CCT (Cam Chain Tensioner) SHOULD BE AWARE OF THIS WARNING! ***[/SIZE]

It has been determined through personal experiences, that it is possible for the cam chain to go slack as the old CCT is removed, allowing the slack to collect at the bottom (crank sprocket) location. That slack can be sufficient to bind the cam chain along the outer edges of the crank sprocket teeth. The binding may prohibit the new CCT from seating properly into position and/or it may allow the chain to skip a tooth on the crank sprocket when the engine is subsequently rotated.

The bottom line is that some of us are strongly recommending the right-side engine cover, located over the crank sprocket/chain area, always be removed before retracting/removing the old CCT. This allows access to the cam chain so it can be tie-wrapped/retained/tensioned (however you wish to accomplish it) while the cam chain is tight and in-time. It prevents the cam chain from drooping off the crank sprocket and slipping out of time.

While it's a small PITA to remove the right-side cover and go to so much trouble with the chain, it's a monumentally larger PITA to re-time the bike if the chain slips a tooth. Should it slip more than one position, the resultant engine damage will be more like nuclear disaster than simple PITA mechanical work.

Consider yourself warned!!!

FJRBluesman · Jul 6, 2010

Excellent post Jeff! Get an admin to close the thread and re-link it to where Ig has your old post.

Thanks again.

BTW - I included RadioHowie's pic of the lower right cover removed, so they can see how they may want to keep tension on the cam chain and guide.

canyonman · Jul 6, 2010

I was able to replace the CCT without removing the right cover but I did have the top cover off and I did keep as much tension on the chain as I could using a wire tie at the TOP of the motor before removing the old CCT

I was able "with a good deal of difficulty" to snake a wire tie around the top of the "rear slipper" and around the timing chain at the front of the motor under the cam sprockets and pull the two towards each other there by maintaining tension on the chain.

I used some very long hemostat like devices and my full vocabulary of 4 letter words to pull it off but was able to keep the chain tensioned while I swapped out the CCT.

Guess I should of taken pics it whould have been a lot easier to explain.

Like Ashe said I wouldn't release that CCT without ensuring in some way that the chain stays tight.

S76 · Jul 6, 2010

FJR080008 said in his last post on the other page:

"Since I had everything apart, I decided to check my intake and exhaust valve clearance and was very delighted to find out that everything (intake & exhaust valves) were within tolerance via specs. from the manual. "

That sounds like a bit of good news. If anything was bent the valve specs would be way off.

Wishing you the best.

FJRBluesman said:

"I would think if the valves hit and damaged the valves the starter would have stopped. I'm not sure the starter has enough Mpffff to get thru a good hit. "

If you check Ionbeams original post when he had the problem he bent the valves just by hitting the starter. The bike never started. So apparently it can happen.

ionbeam · Jul 6, 2010

S76 said:
...If you check Ionbeams original post when he had the problem he bent the valves just by hitting the starter. The bike never started. So apparently it can happen.

Thanks to the wonder of gear ratios. The starter motor and the actual starter gear that spins the motor have a large step-down ratio that multiplies torque in a big way. Not only were zero valves within clearance spec, most of them did not move when the cam turned.

Once there was slack in the cam chain the crushed valve saga clearly started at the crank gear. When the lower cover was removed to look at the crank gear we found that the chain was completely off the gear! This caused a small heart attack over the fear that the non-replaceable crank gear may have been damaged.

FJR98008's finding all the valves to be within spec is a really good omen.