Topic: Desperate cam chain noise measures

[zabzob]

My cam chain won't stop making noise. It's really bad at idle.

Adjusted at 15 degrees ATDC cylinder 1 several times. Inspected and cleaned tensioner spring mechanism. Carbs synced. If you're thinking that it might really be clutch basket rattle, I don't think so. It doesn't decrease with the clutch in.

More desperate measure required? Maybe the spring is weak. Instead of letting it snap in at 15 ATDC, I was thinking of giving it a gentle push in, then letting it spring out. Failing that, I was thinking of doing it at idle. With a screwdriver in the back of the tensioner housing to prevent the bar from moving out, I could release the bolt and very gently increase tension until the noise stops.

Thoughts?

[Cuts Crooked]

.....or you could replace a worn out cam chain?

[zabzob]

The bike has just under 29,000 miles on it, and from searching here I gather that the service internal is 30,000 miles. Well, I guess I'll be doing that this winter...

In the meantime, is the stuff I mentioned "safe" to try?

[HondaMan]

The bike has just under 29,000 miles on it, and from searching here I gather that the service internal is 30,000 miles. Well, I guess I'll be doing that this winter...

In the meantime, is the stuff I mentioned "safe" to try?

I'm presuming a 750 engine here...if you apply extra pressure to the tensioner, it may reduce the noise for a while. But, the noise comes from worn tensioner parts, like the slipper on the front side, or bumps in the roller idler that the tensioner pushes against, or the pivot shaft that the idler arm sits on/in the cases. When you apply extra pressure, it tends to make the rough edges of the rubber pieces then break off, which you will later find up against the oil pump screen. It can also wear through the rubber on the slipper tensioner, right to the metal, and then it puts grindings through the engine, not so good.

A question: does the rattle go away by about 2000 RPM? If it does, that's cam chain. If it doesn't, it is not. Also, which ignition are you running (Dyna S or points), and does your timing 'jitter' on the 2-3 timing mark? With Dyna S, cam chain noise at idle is exceedingly common. With points, if the points advancer shaft is a little bit bent (also very common), the 2-3 side 'jitters' under a timing light examination, which also makes for chain rattle in both the primary and cam chain.

[MCRider]

The bike has just under 29,000 miles on it, and from searching here I gather that the service internal is 30,000 miles. Well, I guess I'll be doing that this winter...

In the meantime, is the stuff I mentioned "safe" to try?

I don't thgink there is a real service interval on the cam chain other than adjusting it at each tuneup which is 1500 miles. It should last forever unless its a performance engine and gets lots of hard throttle on/throttle off transitions. Or if it was let to get loose and ran that way a lot.

There was a thread here not too long ago about static vs dynamic adjustment. I was raised with the static method. Most seemed to agree tho the later manuals 76 on or so mentioned the dynamic method (engine running) and some seem to like it.

While doing either, it is fair to push on the plunger to make sure it is doing its job. Ideally you would then let off, let it find its level, and tighten the lock bolt. Tightening the lock while pushing on the plunger is not fair, not recommended and if that's what it takes to quiet down your engine, you likely do have a problem with worn tensioner parts or the chain itself. If that's what it takes, I'd do it half heartedly and start saving up for a winter rebuild.

[zabzob]

Sorry guys, I really left out some crucial information.

Hondaman: Yes, it is a 750K, '75.

Yep, rattle goes away at 2000 rpm.

I am running electronic ignition... I believe the PO said it was Boyer Bransden. I noticed jitters at the 1-4 timing mark. I can check the 2-3 again later. I've heard that with points, one of the possible causes is an unlubricated points cam, which doesn't really help with electronic ignition. If that is causing rattle, how can I fix it?

I dropped the pan when I was getting this thing running. Not a scrap of metal or plastic in there, so I'm hoping that the tensioner parts are still good.

MCRider: If it turns out that it's not just the jittery electronic ignition causing the rattle, I'll try gentle pressure with the static method. If that doesn't work, I'll try really gentle pressure with the dynamic method.

Thanks for all the help!

[MCRider]

Just remember to run above 2000 rpm and all's well. 

[Really?]

HM knows his stuff!  His words are as good as platinum around these parts!

Ron (MCRider) helped me through the cam chain adjustment when I was doing the 3000 mile tune-up.  Followed his instructions (he simplified and dummified it for me to understand  ) and it worked out perfect.  She is fairly silent now.

[jahmic]

HM knows his stuff!  His words are as good as platinum around these parts!

Ron (MCRider) helped me through the cam chain adjustment when I was doing the 3000 mile tune-up.  Followed his instructions (he simplified and dummified it for me to understand  ) and it worked out perfect.  She is fairly silent now.

I've been following this thread since I seem to have adjusted my cam chain incorrectly (quieter, but still some noise). 

Do you (or anybody else) have a link to the 'cam chain adjustment for dummies' instructions?

[MCRider]

Try this:
http://forums.sohc4.net/index.php?topic=27593.0

[Really?]

Here is my thread on that.

http://forums.sohc4.net/index.php?topic=85421

[jahmic]

Much thanks to you both for the links...

I knew going with the Honda over the zuki was the right choice.  This forum has been priceless.

[dave500]

you might find a carb sync quietens it down if you dont know when it was last done,especially as the po has done some tinkering,,if you do have boyer ignition it doesent use the factory mechanical advance this is removed as these have the advance curve in the black or red box,your timing light check might look confusing as these ignitions also fire all four plugs at once,so youll see the 1/4 and 2/3 marks sort of ghosting over each other.,to set the boyer rev the engine gradually up untill it stops advancing,set the marks at the full advance two scribed lines,dont worry what the idle advance is now showing.