Cam chain tension issue?

Hello,

 

I just finished my first valve adjustment, and I had a concern with the cam chain tension.  I feel like it is too tight.  The valves were the proper clearance, and at the proper orientation on the timing chain, but I am concerned that there is something wrong with the way I installed the chain tensioner.  The engine was definitely more difficult to turn over than before I took off the chain tensioner, and the chain feels tight as a steel cable.  Is this okay?  Does anyone know if I did something wrong?  The bike starts up on the first kick now, but I'm concerned that I may damage something in the engine. 

 

Bike: 2007 RM-Z 450

 

Any help/advice would be greatly appreciated!

You have routed the chain over something it should not be routed past.

You have routed the chain over something it should not be routed past.

 

is there a way for me to know that I have installed the chain correctly?

When you removed the tensioner and the cams what did you do with the chain?  Replace it, zip tie it?  Did it fall at all causing it to possibly fall off or get kinked anyway where it rides on the bottom (off the crank).  The thing is if something bad happened you would know it soon after start up.

 

I can tell you that a properly functioning tensioner makes the cam chain pretty darn tight.  But so that you rest easy  you may want to remove the valve cover and inspect things to see how everything looks now that you have started it.  Back the tensioner off and release it and make sure things are functioning with it.  Ensure the cam chain guide is ok and reset the tensioner like normal.  Obviously you timed it correctly last time as it started right up.

 

Of course pulling the spark plug and spinning the engine will give you a visual but I am sure you did that the first go around.

When you removed the tensioner and the cams what did you do with the chain?  Replace it, zip tie it?  Did it fall at all causing it to possibly fall off or get kinked anyway where it rides on the bottom (off the crank).  The thing is if something bad happened you would know it soon after start up.

 

I can tell you that a properly functioning tensioner makes the cam chain pretty darn tight.  But so that you rest easy  you may want to remove the valve cover and inspect things to see how everything looks now that you have started it.  Back the tensioner off and release it and make sure things are functioning with it.  Ensure the cam chain guide is ok and reset the tensioner like normal.  Obviously you timed it correctly last time as it started right up.

 

Of course pulling the spark plug and spinning the engine will give you a visual but I am sure you did that the first go around.

When I took out the cams, I stuck a wrench through the cam chain to prevent it from falling into the case.  I was a little unsure about the cam timing, as I could have been a tooth off, but apparently everything was good.  the cams would spin just fine, and nothing seemed out of the ordinary.  I installed the tensioner by tightening down the two allen bolts on either side, then tightening the hex nut in the middle that attaches to the spring.  I was concerned, because once the tensioner was installed and tightened down, the motor was noticeably more difficult to turn over.  Besides feeling more resistance from the kick lever, nothing else seemed wrong.  I started the bike up and let it run for a few minutes, and everything seemed normal. 

 

I think the best thing to do would be to remove the tank and the valve cover once more, and remove the tensioner and reinstall to see if it makes any difference. 

UPDATE:

 

I found the problem.  The cam chain tensioner was installed incorrectly.  The little pusher was extended all the way out before being inserted, resulting in too much tension.  Unfortunately, I did end up stripping out all the threads on the intake cam cover that the valve cover bolts fasten into.  The threads just seemed to crumble and break when I threaded them in.  Sad news, now time to call a machine shop. 

Oh man that sucks!...Definitely have to install the tensioner with the plunger backed off completely.   Sorry about that man. 

Oh man that sucks!...Definitely have to install the tensioner with the plunger backed off completely.   Sorry about that man. 

Well, now I know how to do it properly.  I've never had threads do that to me.  The valve cover bolt just started spinning endlessly while I was tightening it with the torque wrench.  Hopefully it isn't too expensive to fix.  I won't be able to ride for a bit anyway because of a broken scaphoid, so it's not that big of a deal.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now