Topic: chain noise on deceleration

[tsflstb]

I've been chasing this noise on my '94 FZR1000.  It's a clicking type noise most noticeable when I'm letting the bike decelerate or engine brake from higher RPMs.  I've ruled out any noise from the brake system.  I thought my chain was bad so I replaced the drive chain and sprockets this weekend and have everything lubed and adjusted.  Still have the noise.  

The drive chain rides on the swingarm when properly adjusted.  I even went up 2 teeth on the rear sprocket to try and move it up off of the swingarm.  There is a well worn plastic rub plate on top of the swingarm.  I've added my own plastic piece on top  of that one (green piece in the pictures) and the sound persists.  It only occurs on deceleration and is more pronounced with more engine braking.  Is it possible the cam chain could be making this noise?  I can't really pinpoint the source since the rest of the bike is so loud.

I'm taking it to a track day in two weeks and it would be nice to eliminate the noise (or at least accept it as normal).  Thanks.

[bucky katt]

what kind of shape are the sprockets in? sounds almost like youre getting a hook shape to the sprocket teeth to me. chainwear plate? use delrin i understand.

[tsflstb]

Both sprockets are new and in good shape.  Actually the old sprockets were still in good shape too.  I thought my old chain was shot so went with new chain/sprockets as a set.  The noise is exactly as it was before.

The replacement plastic OEM chain block is about $120.  I just cut that green piece of plastic out of one of my kid's old toys to quickly add a little tension to the top run.  It didn't change the noise in any way.  If it helped at all I'd track down some delrin and use it.

The noise is only there on deceleration when the top run of the chain has the slack in it.  If I just roll off the throttle or make a slow upshift you can hear it.  I don't feel the clicking through the shifter so it's not coming from the transmission gears as far as I can tell.  I've tried adjusting chain tension and it seems to have no effect, that's why I'm wondering if it may be the engine cam chain or something else I'm missing.  Never heard this noise on another bike, but it might just be a quirk on this one.  It runs great otherwise.

[bucky katt]

dumb question time. are you eyeballing the chain/sprocket alignment or using the marks on the swingarm? i never use the swingarm marks.

[tsflstb]

Yeah, I've thought about alignment.  I'm down to using a dial caliper to measure from the end of the swingarm to the adjusting blocks.  It's within .005" on each side.

I just went for a ride with the chain adjusted tighter than it should be.  With me on the bike, it was taut - zero wiggle where there should be at least 1" at the mid point.  Just wanted to see if that changed the noise, but the clicking/ticking is still there.  Makes me think maybe it's not the chain?

I wish I could ride it with the front sprocket cover off, because it sounds like it's coming from that area.  Unfortunately the clutch slave cylinder mounts there.  Didn't see any signs of wear anywhere around the front sprocket though.  My wife has donated an old cutting board for me to use as a chain guide.  It's probably some form of delrin plastic. I may hack that up and use it as a rub block and put the chain tension back to normal.  I'm thinking the noise may be clutch or transmission related now.

[DME]

What if you pull the clutch at speed and just coast, is the sound still there?

If it is, I´d put the bike on a paddock stand and just spin the rear wheel by hand and listen for it.

[tsflstb]

No, the sound goes away with the clutch pulled in.

It seems more related to the amount of engine braking going on than to speed.

[DME]

I had a prominent clicking sound on my CB750 when the small end of one rod had worn out.
It was only heard on decelleration or when the revs were held steady at 3000 rpm or higher with no load on the engine.
But there was no way that sound could be mistaken for a chain problem.

Has the sound always been there since you bought it, or has it developed recently?
Checked wheelbearings?
Rubber cushions in sprocket holder?

[razor02097]

Alloy wheels have buffer rubber in them.  did you check your rubber pads when you took the wheel off to change the sprocket?  The accelerate side is much thicker then the decelerate side so it may be enough play to cause your noise...or not 

[tsflstb]

This noise really sounds like it's outside of the engine case, but I could be wrong.  I hope it's not a rod bearing or transmission bearing, but I seem to be running out of easy things to check.  

I can't really say when I first noticed it, but since I've had it running and on the road consistently it's been there.

Wheel bearings and cush drive appear OK to me.  The noise originates from somewhere around the front sprocket.  I'll check that area again closely, but I can't see any issue there.

At this point I'm going to put slack back in the chain and fab up a thicker chain guide from that old cutting board.  Probably not the ultimate solution, but it should keep the chain healthy.  I need to get it prep'd for a track day on the 27th, so I don't have time to tear into the engine internals right now.  I wear ear plugs at the track, so that should fix the problem temporarily anyway...

[Cyprusice]

I am curious as to if you had found a solution for this problem yet? I have a completely different bike (1982 Honda 650 Nighthawk) with what seems to be the exact same problem. I only hear this noise when I let the engine brake the bike, yet when I pull the clutch in the noise disappears. This started happening just last week and I also though it was my chain being too dry so I lubed her up and the noise is still there. I am also concerned that this could  be some transmission problem or clutch problem.

[mystic_1]

Is what you guys hearing perhaps coming from the transmission gears themselves?  When you engine brake, the forces in the transmission are loaded against the "back sides" of the gear teeth, a place that only sees any real load under engine braking conditions.  75%¹ of the time you are pushing forwards through the gearbox so 75%¹ of the wear occurs on the 'forward' faces of the gear teeth.  If you tear down a well used gearbox you can see this wear pattern in action.  This is also the same reason that your sprockets wear into hooks, most of the time the forces are only applied on one side of the teeth.

Anyway, the backsides of the gears don't wear in like the frontsides do so you could just be hearing gear noise as a result.  Possible?

mystic_1




(1) the figure 75% is a Scientific Wild Ass Guess.

[Dawdlin Dog]

I had what sounded like exactly the same problem on my 550, turned out to be the primary drive chain rubbing on the oil journal in the bottom crank case half 

I'm not familiar with either of the bikes mentioned so this might not be possible but if you can drain the oil, take the sump pan off and have a look/poke around with your fingers thats how I discovered my problem.

Hope this helps

[Uncle Ernie]

I am guessing wheel out of alignment (use a straight edge instead of a caliper), posibly primary chain is loose, or loose clutch plates.

BTW- I sure hope you loosened up your chain again.  Riding with a chain too tight can eat your tranmission pretty fast.

[tsflstb]

I checked and re-checked everything.  Bought a cheap complete swingarm assembly on Ebay just to use the chain guide and replaced that.

A trusted local mechanic who raced a similar bike in the 90's rode it and wasn't alarmed by the noise. 

I took it to a trackday and nothing bad happened at 130 MPH so I've stopped worrying about it.  I'm thinking it might be the backside of the gears like Mystic suggested.