Timing chain tensioner

Will be replacing the timing chain on my '99 420 over the upcoming weekend as a preventative mesure while shimming the valves. What I need to know is what to look out for with the tensioner. I've had it apart before when doing my top end and I find the unit sort of funky, as it could be installed incorrectly very easily. Also how far out should it extend once the new chain is back in ? What kind of service life does this part have? Thanks in advance for your time.

[This message has been edited by Hugh LePage (edited 08-07-2001).]

Good question. The tensioner should move freely and have a good strong spring tension when extended. I have heard many times that those things don't wear out unless you seize the motor and do some catostrophic motor damage. I would pretty hard to measure the extension of it anyway with the motor all together. Are you experiencing some cam chain noise to make you think it's on it's way out?


Yes, it got progressively more noisy and more so the last couple of rides. It is not CB related as this has been checked. When doing the top end over the winter I noticed that the chain had some minor binding points. They may of gotten worst as the noise detected has a swishing regular rythm to it. I will have apart over the weekend and let you know what I find. As for timing chain life I think Hick mentioned that it should be replaced when ever doing a top end which makes sense to me.

[This message has been edited by Hugh LePage (edited 08-09-2001).]

Huh, thats interesting, I know on a car your supposed to do em every 100 K or so, I have never seen the timeing chain mentioned as regular maintance, books always say "examine and replace if needed" What the heck dose that mean??? Anyone else replace chains as routiene maint? I have street bikes with high milage that I have never even thought about changing the chains on. Of course my VFR has gear driven cams :) . They are noisy but they ROCK.

I wonder if you feel the cahin is worne if you shold replace the cam and crank sprockets too like you do on the drive chain ? Shouldnt the chain and gears were together? This may be a good question for a GOOD bike mech. Like thumper racing or someone?

[This message has been edited by WR_Jason (edited 08-09-2001).]

I inspected my tensioner and found that it

does not lock when fully retracted, I guess I should replace it.

I tried to line up the I mark as the manual

states, but every time I try the compression

causes it to roate past. How are you guys

getting around this problem?


Do you have the spark plug out? If not yank that rascal out. If that doesn't work, put a socket on your flywheel nut and use to control the amount of movement you get.

As far as the cam chain tensioner not staying retracted, did you do as the manual says and push it in with a phillips screwdrive and rotate to the locked position? It is crucial that the cam chain tensioner be retracted when you install it. If it won't stay retracted, a new one is probably a good idea.


Changed timing chain over the weekend. Went in by mag cover side. Everything went smoothly and reshimmed valves while at it. As for chain wear could not detect much differance betwwen old and new exept for wear marks on face / contact area of chain. The tensioner is a little over half way out which is what it was like before with old chain. Oh well, at least I have peace of mind that all is O.K. and that bike is sellable when the time comes. B.T.W. a good way to check if the tensioner is acting on the push pad ( rubber binder ) is to have the motor at TDC and to then unscrew the tensioner evenly off of motor while observing

the daylight between the motor and tensioner. When tensioner is finally all way out the screw heads will begin moving away from tensioner. I still had at least a 1/4" to go so I was safe. The old chain had some tight spots / kinks in it though.

[This message has been edited by Hugh LePage (edited 08-13-2001).]

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