Topic: Cam Chain Noise

[gaijin]

Well today I tried adjusting my 400f's camchain to see if I could reduce the clatter. With the bike idling I unlocked the nut and backed the bolt out about 1/2 a turn. The noise became much louder! The bolt doesn't seem stripped and it's not siezed, but I can't seem to get the noise to go back to how it was before I adjusted it, as I've made it worse.

I've seen two different methods recommended for adjusting the tension, one with the engine off and one with it idling. Aside from hot engine parts, is there any advantages to having the engine off (and positioned at uh, something after TDC, I forget how many degrees) while doing this? Should I just try again or do something differently? Thanks guys for any suggestions..!

[MPH2]

15* after TDC on cylinder no. 1 so the slack is in the rear of the enigine for the tensioner to do it's job 

[gaijin]

Thanks guys, I'll give it another go after I synch the carbs. I'd been putting it off because I haven't found a cheap set of guages for that, but looks like it's time to get some anyways. Maybe time to install these carb kits tooo

[Tim2005]

I prefer the static 15 degrees after TDC method, when I know the tensioner is in good condition. If it is still noisy after that, or I don't know the engine, I find that the best way is to pull the cam cover off and check that the chain has tensioned...or more likely find that it hasn't.

[gaijin]

Ok. I just synched the carbs the other day and tried to adjust the cam chain tension again, but there wansn't any change in the chain rattle. Since the noise increased after I tried to adjust it the first time, I think the tensioner springs could need replacing. I've yet to pull the cam over off and have a look inside, but that will happen soon. The engine only has 9500 miles on it; the chain should have some life left, maybe?

Can the tensioner springs be replaced without cracking the case open? That bolt, what the parts list calls the oil check bolt, looks like the only thing that stands in the way of replacing the springs...$4 for both from Servicehonda.

[oldbiker]

According to the manual, run the motor at a fast idle (1200rpm) slacken off the lock bolt and the spring should do the rest! Many people find that removing the blanking plug at the top of the tunnel and applying LIGHT pressure to the plunger, (part 7 in the diagram in the preceding answer), thus assisting the spring, does the job better.

[gaijin]

Ok, I finally gave this problem another go after changing my needle position and re-syching my carbs. (mixture was way too rich, runs better now)

Ran the bike at 1200rpm, slackened off the lock bolt, and the chain noise didn't diminish, or even change. Stopped the engine, rotated it to 15 degrees after TDC, removed the bolt that goes over the tensioner springs and tried pushing a bit with a long screwdriver. Nothing budged... 

Oldbiker, you mention a blanking plug. Is that something that's not in the diagram that goes over the springs, that must be removed to push the tensioner? I can see something that looks like either an o-ring or the top of a spring in there under the bolt, and it's not moving. Any thoughts? I guess the next step is pulling the cover off and actually looking instead of guessing about what's going on. Thanks guys...

[Bodi]

Under the bolt you should see the top of the adjuster rod. The spring is captive and comes out from inside the crankcase.
Overtightening the bolt can distort the rod (even though the bolt hits a flat) and jam her up a bit, but since it got louder when you loosened the bolt it can't be really jammed badly.
Get a nail or whatever and push down on the end of the rod. You should feel definite up and down movement if you turn the crank forewards and backwards a bit (backwards rotation should pop it up pretty good), if it doesn't move at all then it is jammed. You can try this with the engine running and press it until the rattling noise just goes away, but those hot headers are might close. If you rock the crank back and forth close to that 15 past TDC 1-4 you will feel when it's snug. If you really reef down on it you'll overtension the chain and the guide will wear rather quickly - plus potentially the chain could snap.
I've never seen a gush of oil come out the cap with the engine running but you could get a bit of a leak I suppose.

[oldbiker]

As Bodi says, the springs and push bar only come out from inside the crankcase. This was a known problem on this motor when the U shaped cam chain tensioner arm became seized (frozen) in place. If you cannot detect any movement in the system, I would wait until the next time you do a major overhaul and make a point of checking this for free action. Sorry I can't be of more help.

[hymodyne]

a mechanic recently told me that the proper way to adjust the cam tensioner is to do so when the bike is not running.

I recently had to replace an intake valve spring. while I  had the head anc cam cover off, I took out the tensioner and checked it to see if my movements of the stud actually turned the mechanisim that moved the tensioner rub bar in and out. It did, so when I put the top end back together, I pushed the tensioner rub bar all the way back, and then tightened the locknut enough to hold it in that "no cam chain tension" position.

after I finished assembling the top end, I then released the locknut and listened to hear the rub bar, spring back out against the camchain.  when I heard  this, I re-tighened the locknut.

hym

[gaijin]

Thanks again guys for all the info. I know it's kind of an old topic that's been covered before, but I've been trying to be systematic about fixing this and so far nothing's worked So it's down to taking things apart it seems!

Bodi, I haven't actually tried rocking the engine back and forth to feel for movement from the adjuster rod, I only tried applying pressure at one point and felt no give. So I'll try that and hopefully it won't be seized, but I expect it will be.

Oldbiker, I'm arranging to have my "parts bike" hauled to the shop I'm apprenticing at so I can try swapping motors, so I can then tear into the other one. Might be a good time to replace that damned leaky head gasket hmmmm....

Hymodyne, I definitely prefer trying the methods without the bike running  I have no desire to burn myself on those pipes.

Supersport, I hope my tensioner arm won't look like that but it might.

Cheers guys, hopefully I'll have better news next time I post about this crap!