WENT FOR A NICE RIDE AND THEN THIS HAPPENED.............

[timbeck]

Great day for a ride until I was approaching a stop sign. Off the gas and coasting to a stop a metallic noise came from the engine area, I was a bit surprised to say the least, but had to move forward and there was no noise as long as I was giving it some throttle. As soon as I back off the gas the noise appears and it dosen't sound good. I drove home about 5 miles and it ran fine until I let off the gas. Any ideas guy's.......

 

[yamageddon]

Cam chain adjustment(?) At idle it makes more noise when not adjusted.

 

[timbeck]

It seems fine at idle but the clank kind of noise appears any time I am off the gas coasting along. The rhythm seems to copy wheel speed. I'm thinking something in the trans perhaps a bearing.

 

[yamageddon]

So it seems in the drive train section then. Front sprocket loose? Chain adjustment? Is it rattling against something? Or worse; clutch? Is the clutch working properly? Hard to take a wild guess of course, but try to look for the obvious first before you dismantle the lot. Put the bike on the center stand and in first gear (with the bike NOT running of course!) Move the rear wheel by hand. Maybe you'll notice something or hear something rattling.

 

[timbeck]

Sprocket tight [ I was hoping that was the culprit] chain ok, clutch was working good, trying to move the rear wheel in first gear is a bit difficult.

 

[yamageddon]

Sprocket tight [ I was hoping that was the culprit] chain ok, clutch was working good, trying to move the rear wheel in first gear is a bit difficult.

I meant: Just try to move the rear wheel back an forth to see if there is a lot of play that shouldn't be there and perhaps causes the noise. It's to try to diagnose where that sound is coming from.

 

[timbeck]

Not really much movement and no noise . I think I'm having YAMAGEDDON. lol

 

[yamageddon]

Not really much movement and no noise . I think I'm having YAMAGEDDON. lol

LOL! What's in a name eh?
When you move the bike (like pushing it forward without the engine running) can you hear it then?
Or put it in gear, pull the clutch and push the bike forward/backward.

 

[timbeck]

Moving the bike forward and back about 8ft results in no noise. Also clutch in, in first gear, no noise, obviously a bit harder to push.Tomorrow I will get it on the street for some further tests. Thanks for your help.

 

[yamageddon]

I hope it's not to bad. Curious what it is...

 

[MaxPete]

 

[TwoManyXS1Bs]

Only during off-throttle, engine-brake coasting?
Only in gear, clutch engaged?
Any gear?

The bottom part of the chain will be tight.
A chain with tight/loose spots could be skipping on the top of the swingarm, or whipping on the chainguard.

The bottom part of the engine sprocket will be pulling the output bearing rearward, instead of the top part of the engine sprocket, which normally also pulls rearward, so don't see much difference there.

Any engaged gears will have loads applied to the opposite faces, instead of driven faces. This would be dependant on which gear you're in.

Forces on the clutch basket damper springs would be reversed. Broken spring(s) could get very loose in this scenario.

Forces on the mainshaft double-row bearing (behind the clutch) would be pressing down, instead of up. Pulling the clutch lever applies rightward force on that bearing, and would change the sound of a damaged bearing.

I've refilled my ...

 

[gggGary]

IMHO First step duplicate on a stand, pin point location of the noise. Stethoscope, large screwdriver whatever it takes.

 

[timbeck]

Thanks for the input guy's. 2M yes the noise is present in any gear while off the gas coasting. I'm on the case........
tim


PS---I may be better off selling popcorn.....lol

 

[hogtyed]

Did you check your cam chain? You said earlier in post #5 that chain tension was good, but didn't specify cam or drive.

 

[timbeck]

First of all a big thanks to all that chimed in with things to check and try. This forum saved me from pulling out what little hair I have. This morning I drove the bike down my street, the noise was bad I then removed the right side cover to check the clutch area, things looked fine. The case cover gasket did not cooperate and I had to rob the right side case cover from my spare engine. I took Gary's advise and got the rear wheel up, that's when I realized the chain was very tight. Last week I checked and tightened the front sprocket and adj the chain. The chain had the right amount of slack with the wheel up but with the wheel down it was very tight. Over the years I've tightened chains wheel up and wheel down but today I've learned my lesson. Thanks again to all.

 

[timbeck]

After taking it out for a ride it seems the tightness of the drive chain must have cocked the sprocket shaft enough to cause the the banging and snapping noise. No noise now but I hope there is no lasting damage......
tim

 

[5twins]

Yes, you always need to check a chain adjustment by "loading" the bike, sitting on it. The rear shocks compress a bit, the swingarm moves up some and is more in a straight line with the countershaft sprocket and swingarm pivot bolt. The distance between the front and rear sprockets grows a little, and the chain gets tighter.

 

[gggGary]

Never hurts to double check rear sprocket bolts.

 

[timbeck]

Thanks for the reminder Gary, I'll get on that first thing in the AM.
tim