Topic: Cam Chain Noise

[mlinder]

I do believe the cam chain is a bit noisy on the 350f.
The amount of noise doesn't change if I pull the clutch in.
I went to 'adjust' it, but no real difference was heard, far as I can tell.
Noise disappears at above 2.5k rpm.
What am I looking at here, broken tensioner? too-stretched cam chain?

[UnCrash]

On my 750f the thing was stuck in the out position.

try unscrewing the adjuster and pushing in the pin from the open end.  Does this help the noise?

I took the tensioner arm thingy off, apart and cleaned it up. 

Immense improvement, and it was an easy 30 minute job as well.

Best o luck

Ben

[Al_Aaraaf]

I'm having a similar problem on my 550. Adjusted tappets, cam chain and still that blasted noise at idle. Was beginning to fear it was comming from the bottom end, even though I couldn't localize the sound to there with a screw driver and my organic sound receiver turned up to 11 on the sensitivity scale. Alas, there is another possibility...

This is second hand knowledge, but I found after (seemingly hours) of reading that experienced guys on here say that a similar noise is made when the carbs are out of sync. Some nonesense about the cylinders struggling against each other as they fire. I just got a Morgan carb-tune in this week so I'll know for sure after the weekend I hope.

May have to clean up my carbs first though. Got-damned floats on one of the carbs was sticking on the way to work. Accelerated like ass, and then poured gasoline all over the parking lot. Turned out it was not one, but two carbs! What are the chances of that, eh? I blame BP. I've owned the bike since October (riding damned near every day through the winter) and nothing like this until I gassed up late last night. Bastages.

[mikedialect]

On my 750f the thing was stuck in the out position.

try unscrewing the adjuster and pushing in the pin from the open end.  Does this help the noise?

I took the tensioner arm thingy off, apart and cleaned it up. 

Immense improvement, and it was an easy 30 minute job as well.

Best o luck

Ben

I did not know you could take it out! I suppose that would be the best way to check and see if the mechanism is stuck?

[mlinder]

It would be from unsynched carbs if I could pull the clutch in and the noise dissapates, but the noise is constant, clutch in or out.

[UnCrash]

Ya,

Now that I've had it out I could tell if it got stuck again.

I don't have the correct words for this stuff at all but here goes.  The tensioner arm housing is in the rear center of the top end of the engine.  It is a barrel within which a pin/arm and spring are housed.  If that pin is all the way out at the end of the barrel you may not have any tension on your cam chain.

This was the case for me.  The thing rattled like hell. I turned the adjuster screws etc and nothing happened.  It still sounded like ball bearings and munched up metal in there.  So... I took the airbox and the carb drains off and pulled the housing for the cam chain.  

The whole thing was just road grimed up.  WD40 and some superfine grit sandpaper cleaned the mess up.  I reassembled, and put it on the bike and now had some plunger action!

I followed the normal tensioner procedure and she's much happier now.

Cheers,

Ben

[Al_Aaraaf]

It would be from unsynched carbs if I could pull the clutch in and the noise dissapates, but the noise is constant, clutch in or out.

I don't understand that. Why would it matter if your clutch was disengaged? I don't know about you, but I don't turn my engine off between shifts.   

Seriously, the clutch has nothing to do with idle speed (load difference is next to nothing in neutral). The symptoms you're describing could just as easily be any component between the air box and the transmission if you're only going by the clutch position. The particular sound that's being made gives a clue to what it might be, and if you successfully adjusted the cam chain tensioner (if the adjuster was not jambed) and the sound didn't change at all-- then it seems logical to recall when the last time the carbs were sync'd. 

[gregimotis]

My 750F also had the tensioner stuck in the 'out' position.  Took it off, cleaned it up, and only then did it reduce cam rattle.

That was a month ago, right afterward I adjusted the valve clearance, this also reduced some noise and then synched the carbs for the first time (Got a Morgan for my birthday, which is what prompted all this).  Synching the carbs did reduce engine noise.

I think it's pretty difficult to tell just what is making noise in there - the carbs caused a rattle pretty similar to the cam chain if you ask me.

[Tim2005]

The 350f tensioner is a different design to the 750s - same as the 400f though. Do a search of the site, there's a thread here somewhere about 400f camchain adjuster problems which has some excellent pics/diagrams to assist.

[mlinder]

It would be from unsynched carbs if I could pull the clutch in and the noise dissapates, but the noise is constant, clutch in or out.

I don't understand that. Why would it matter if your clutch was disengaged? I don't know about you, but I don't turn my engine off between shifts.   

Seriously, the clutch has nothing to do with idle speed (load difference is next to nothing in neutral). The symptoms you're describing could just as easily be any component between the air box and the transmission if you're only going by the clutch position. The particular sound that's being made gives a clue to what it might be, and if you successfully adjusted the cam chain tensioner (if the adjuster was not jambed) and the sound didn't change at all-- then it seems logical to recall when the last time the carbs were sync'd. 

I don't understand it either, but it's a fact. My cb750 did it, so does everyone elses cb750 here.
Carbs out of synch, cam chain rattles. Pull in clutch with carbs out of synch, cam chain doesn't rattle.

[Gordon]

I don't understand it either, but it's a fact. My cb750 did it, so does everyone elses cb750 here.
Carbs out of synch, cam chain rattles. Pull in clutch with carbs out of synch, cam chain doesn't rattle.

You're confusing clutch basket rattle with cam chain rattle.  Pulling in the clutch has no effect on cam chain tension or anything else on the top end of the engine. 

Synching the carbs can help quiet down a noisy cam chain, but making sure the cam chain tensioner is in good working condition should be the top priority.

[mlinder]

I don't understand it either, but it's a fact. My cb750 did it, so does everyone elses cb750 here.
Carbs out of synch, cam chain rattles. Pull in clutch with carbs out of synch, cam chain doesn't rattle.

You're confusing clutch basket rattle with cam chain rattle.  Pulling in the clutch has no effect on cam chain tension or anything else on the top end of the engine. 

Synching the carbs can help quiet down a noisy cam chain, but making sure the cam chain tensioner is in good working condition should be the top priority.

Ah, ok.

The rattle from the whole clutch issue is from unsynched carbs and uneven power being engaged to clutch parts.
OK, clear enough now.

So, back to cam chain, it looks like perhaps the plunger could be at fault there. loosening the nut that hold the plunger in place wont do anything if
a:) the spring on the plunger is too dead to push the u shaped arm to increase tension
b:) The plunger adn spring assembly is frozen up from years of neglect, therefore not moving the u arm to increase tension.

If it's one of these, what can I do without taking much apart?

Can I remove the plunger? The spring?
Will the spring fall into the crank case?

[jesusno2]

i adjusted my cam chain synced my carbs it still sounds like a bucket of bearings I think my primary chain is the culprit for that noise. probabbly alot of other bikes as well. i know the clutch basket is worn some cause i have the clutch noise also that goes away well i pull the lever in.

[Tom Stark]

I don't understand it either, but it's a fact. My cb750 did it, so does everyone elses cb750 here.
Carbs out of synch, cam chain rattles. Pull in clutch with carbs out of synch, cam chain doesn't rattle.

I would have thought you were full of it.  I really could see no way this would be true.  but sure enough, tried it with my bike, (KNOW the carbs are not synced) and it sure is just as you say!  Sort of wild!
Tom

[mikedialect]

So, back to cam chain, it looks like perhaps the plunger could be at fault there. loosening the nut that hold the plunger in place wont do anything if
a:) the spring on the plunger is too dead to push the u shaped arm to increase tension
b:) The plunger adn spring assembly is frozen up from years of neglect, therefore not moving the u arm to increase tension.

If it's one of these, what can I do without taking much apart?

Can I remove the plunger? The spring?
Will the spring fall into the crank case?

I'm also curious about this- in regards to what will happen when I pull the tensioner assembly out. If it does simply pull out what is the best way to clean it? A few good shots of WD and moving things back and forth?

[Tom Stark]

Mine was reasonably stuck.  What I did was loosen up the bolt, (after the motor was turned over to proper position), and used the end of a stubby phillips head screw driver to "nudge" the rod and get it to move forward.  I then tightened the bolt and lock nut.  Obviously this will not work if it is really stuck, but if it is just a little stuck, it can work.  Tom

[Bodi]

The 350/400 tensioner is completely different from the 750. You can't remove much any of it without pulling the head, and the bit that usually causes trouble - the pivot knuckle that gets damaged by a loose chain - requires splitting the main cases for access.
 If you take out the bolt above the locking bolt, nothing falls out as the springs are captive inside the engine case. You CAN push on the end of the adjuster rod (the locking bolt presses against this rod) and "help" the old tired springs. That will silence the chain if the knuckle isn't damaged and locked solid.
After many miles the stock chain stretches and the tensioner slides wear, possibly beyond adjustability. New (better) chains are available and the slide parts are available - for now - if you have a 350-4 or 400F you want to keep a while, it might be in your interest to get the slides and rubber blocks now before they're unobtainium.
I thought there was a file in the archives with an excellent explanation of how the adjuster works, what goes wrong with it, and several ways to get it working... but I can't find it now.

[andy750]

You can remove the cam chain tensioner if you remove the lower half of the airbox (even better to remove all of it but not required). There are 3 bolts (I think) that hold it in place and it comes away easily. I have done this on my CB750 after stripping the adjuster bolt. Its relatively easy process and once out you can see how the tensioner works very easily.

cheers
Andy

[Gordon]

You can remove the cam chain tensioner if you remove the lower half of the airbox (even better to remove all of it but not required). There are 3 bolts (I think) that hold it in place and it comes away easily. I have done this on my CB750 after stripping the adjuster bolt. Its relatively easy process and once out you can see how the tensioner works very easily.

cheers
Andy

The bike in question is a 350F, not a 750.  Like Bodi said, it's a completely different style tensioner that can't be removed from the outside of the engine.

[mlinder]

Yes, sorry.
It's confusing. I have a 750 and a 350.
The one I'm talking about in this thread is the 350.
So, the pertinent question... Can I remove the plunger and try to get it to put more pressure on the U shaped thingamabob?

[andy750]

Oops sorry i got confused about the bike. thanks for letting me know.

cheers,
Andy

[ieism]

If it's stuck, just jiggle it. This works for a '76 550f only. 

[Gordon]

If it's stuck, just jiggle it.

That's good advice for many tricky situations in life!

[Al_Aaraaf]

It would be from unsynched carbs if I could pull the clutch in and the noise dissapates, but the noise is constant, clutch in or out.

I don't understand that. Why would it matter if your clutch was disengaged? I don't know about you, but I don't turn my engine off between shifts.   

Seriously, the clutch has nothing to do with idle speed (load difference is next to nothing in neutral). The symptoms you're describing could just as easily be any component between the air box and the transmission if you're only going by the clutch position. The particular sound that's being made gives a clue to what it might be, and if you successfully adjusted the cam chain tensioner (if the adjuster was not jambed) and the sound didn't change at all-- then it seems logical to recall when the last time the carbs were sync'd. 

I don't understand it either, but it's a fact. My cb750 did it, so does everyone elses cb750 here.
Carbs out of synch, cam chain rattles. Pull in clutch with carbs out of synch, cam chain doesn't rattle.

Crap... Well, that's something new. I'm glad I chimed in on this thread. I'll be sure to remember that when I try to track down the noise again. My rattle doesn't stop with the clutch disengaged. Maybe my tensioner adjuster is toast after all. Or maybe I just need to "jiggle it" as ieism said.

[mlinder]

No, I was wrong. As others pointed out, this was clutch basket rattle from unsynched carbs, not cam chain rattle.

That makes a lot more sense.

If the noise doesnt go away, then it is cam chain noise, and if it does, it's clutch basket rattle.

Or at least that's what I'm picking up from what people are saying so far in this thread.