Cam Chain Noise

[OrangevaleFJR]

Not to beat a dead horse here, nor start a whole new round of NEPRT style postings, but now you know why I change my oil far too often. Hy-Vo chains can go literally forever when kept happy with lots o good clean lube, and a tensioner that does what it's name implies.

I figured changing the oil every 3000 miles was good enough.

Must be the tensioner.

 

[radman]

I figured changing the oil every 3000 miles was good enough. Must be the tensioner.

I had a big long post in reply, but don't wanna get into it. 3 grand should be good enough, and if a tensioner dumps, it doesn't really matter, does it

 

[painman]

So in my vast unlimited knowledge could one perceive tell-tale signs of this problem as Ion did by 1. the fluctuating of the idle needle on the dash tach, and 2. possibly one putting a timing light on the sight window on the side of the engine and watching the timing mark (pointer), (which is unadjustabe) fluctuate on the pickup rotor? Could these be indicators of pending doom? PM. <><

 

[FJRAust]

In the case of my old FJR I can hear the timing chain. No need for timing lights..

Mine has 60 000 KM on it and it's time for a tensioner.

Fortunately the bike is in at the moment for the Ticker fix, so I've asked that they replace timing chain and tensioner and also have a look at the chain guides.

I wouldn't change the timing chain just the tensioner but the head is off so the vast majority of the work is done..It's just easy to do now..

I should clarify just when I can hear the timing chain rattle. Just as the bike is warming up. once the fast idle has stopped and the RPM's are just under 1000 RPM I can hear it, as the engine comes to temperature and the idle goes up to about 1100 RPM it's all quiet.

This to me says address the issue before things get nasty.

 

[charismaticmegafauna]

<snip>So in my vast unlimited knowledge could one perceive tell-tale signs of this problem ....

FJRAust: "In the case of my old FJR I can hear the timing chain."

Any unusual noise on the right-hand side of the engine (FJR) should be 'suspect'. A properly adjusted cam chain would exhibit no noise. In an effort to eliminate cam-chain problems, manufacturers have, often, gone over-board and 'tighten-the-hell' out of cam-chains -- to the point where there is significant 'whine' in the cam-chain drive. An overly tight chain will whine (the lesser of two evils). A loose cam chain will rattle.

Also, if any manufacturer has a replacement cam-chain tensioner (up-dated part #, for instance) and you have any doubt about yours -- might not be a bad idea to ask about and maybe replace yours with the up-dated one.

 

[ionbeam]

So far Yamaha hasn't updated the tensioner, same P/N for all years.

 

[Fred W]

Sorry to kickstart this thread, but reading through it, it occurs to me that the chain tensioner function must be somewhat different than the automotive ones that I am used to dealing with (mostly SAAB and BMW cars).

On the auto CCT's that I've messed with, there is one large spring that provides the actual thrust to the push rod that engages the chain guide. This is how the chain's tension is set. Then there is a ratchet mechanism to prevent the push rod from being pressed back into the CCT body during high rpms. The ratchet is somewhat coarse. I believe this is so that each detent allows enough slop to provide for the chain to change length when heating and cooling. But clearly each ratchet detent would be much smaller than what would allow the chain to hop the drive teeth on the crank sprocket.

If this is also how the FJR CCT is designed to operate then there are only a couple of possibilities as to how you would have a catastrophic failure such as Ion's.

The chain could stretch (wear actually) to the point that the CCT is fully extended. There will obviously be a finite range that the tensioner will work. At that point it could no longer add tension to the chain.

The CCT ratchet could be defective allowing the plunger to be forced back into the body of the tensioner. This should be easily identified by inspection and manipulation of the assembly.

The internal spring in the CCT could lose some of it's tension and not increment the CCT to the next detent. If this were the case, pressing the plunger in to the next ratchet detent would temporarily "cure" the noisy chain. I would also think the spring's tension could be measured easily when removed.

On the car tensioners, there is a procedure to first remove the internal spring and then remove the CCT body to inspect how extended the plunger is when installed. You have to remove the spring first or the plunger would just fully extend in the course of removal. By measuring the plunger you can determine how worn the chain and guides are and replace them before they even get noisy.

Thoughts?

 

[FJRAust]

Hi again Fred

I agree with your explaination and assesment. I've not disassembled the FJR to know precisely how it's built but expect it's similar to other tentioners. My XT tentioner is functionally as you have explained.

When the bike shop talked about replacing the tentioner I suspect they actually mean the tentioner spring as when I asked for the guides to be inspected and possibly changed the responce was that it's very inlikely they would need to be changed but the as they bike will be in such a state of disassembly why not do the cam chain and tentioner!

I know on my XT the tentioner puts pressure on the rear guide..