Whats that rattle
#1
08-18-2018, 08:39 AM
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Whats that rattle
Hi All,
So I have recently bought a 1996 900 RR as a project and it's fair to say that she has been..... Played about with.. I bought her as a clearance spares or repair from a dealer about 70 miles away, full MOT, and rode her all the way home at around 60-70mph happily. But.... there is a rattle... It sounds like cam's or valves, but I don't think it can be?? I have done a fair amount of research on forums and things but am starting to get to a point where I'm baffled - here's why..
It only makes the sound under load.. Sitting idling, or even revving it up to around 6000 revs while stationary there is no sign of rattle. I read about sloppy cam chain tensioners, so I bought an APE manual CTT - fitted it, adjusted the chain properly... still rattles..
So I then read about exhaust gaskets failing causing it.. So I dropped the headers, cleaned out the shocking old gaskets, cleaned everything - replaced them with nice new gaskets.... still rattles..
Checked the drive chain and sprockets - they are fine
So today I have put het up on stands so the rear wheel is lifted - started her, got her warm, then put her into gear - no rattle... changed gears ran her up... no rattle.
Checked the wheel bearings and that they all free wheel - all fine..
Took her off the stands sat on her and went to pull away - there's the rattle again...
So im now thinking it can't be the cams, valves, cam chain or sprockets as the noise would be there when running on the stands wouldn't it?
Could it be piston slap when she is trying to pull the weight of the bike?
Any other ideas of guidance gratefully received!!
So I have recently bought a 1996 900 RR as a project and it's fair to say that she has been..... Played about with.. I bought her as a clearance spares or repair from a dealer about 70 miles away, full MOT, and rode her all the way home at around 60-70mph happily. But.... there is a rattle... It sounds like cam's or valves, but I don't think it can be?? I have done a fair amount of research on forums and things but am starting to get to a point where I'm baffled - here's why..
It only makes the sound under load.. Sitting idling, or even revving it up to around 6000 revs while stationary there is no sign of rattle. I read about sloppy cam chain tensioners, so I bought an APE manual CTT - fitted it, adjusted the chain properly... still rattles..
So I then read about exhaust gaskets failing causing it.. So I dropped the headers, cleaned out the shocking old gaskets, cleaned everything - replaced them with nice new gaskets.... still rattles..
Checked the drive chain and sprockets - they are fine
So today I have put het up on stands so the rear wheel is lifted - started her, got her warm, then put her into gear - no rattle... changed gears ran her up... no rattle.
Checked the wheel bearings and that they all free wheel - all fine..
Took her off the stands sat on her and went to pull away - there's the rattle again...
So im now thinking it can't be the cams, valves, cam chain or sprockets as the noise would be there when running on the stands wouldn't it?
Could it be piston slap when she is trying to pull the weight of the bike?
Any other ideas of guidance gratefully received!!
#2
01-18-2019, 03:06 AM
Just a few ideas...
Loose front fender. My yzf front end self destructed when I installed a bigger tire that made my speedo correct. Fender got destroyed, and now rattles.
Is there some sort of clutch feature on the cbr when downshifting from high speed on the track? You know, slipper clutch? Maybe that's messed up. Or maybe it's just an old clutch.
Is there a valve in the exhaust? Yamaha liked them on 80's and 90's bikes, but I don't remember Honda doing any back then.
My fzr400 suddenly started making a knocking sound one day. It sounded like a spun bearing and pistons whacking the head. But, it wasn't. After disassembly, it all looked fine. I figured it was that busted up generator cover making contact with the magnet or sensor or something . Too many races and crashes!
So I installed a yzf600 engine, and under load in first from a stop it makes a creaking noise. A cross between a clunk and a rattle. Kinda like the engine isn't bolted in right. Of course, it wouldn't be. The frame is a rhombus due to too many crashes!
The chain doesn't line up on anybody's fzr400/yzf600 hybrid (countershaft is offset more on the bigger bike because of the wider wheel). Maybe that's the creaking noise.
And the chain used to rattle against a heel guard bolt until I shaved that bolt down. But, it only did that when the chain was a bit loose and needed an adjustment.
Maybe your chain/wheel aren't lined up correctly either, or is loose, and the chain is hitting something.
Maybe there's something in the exhaust. When I bought the yzf600, somebody had stuffed pink fiberglass insulation in the muffler, and it was as quiet as a car. Who knows what could be lurking in yours. Maybe a rock or a broken piece of metal.
Let us know what it turns out to be.
Loose front fender. My yzf front end self destructed when I installed a bigger tire that made my speedo correct. Fender got destroyed, and now rattles.
Is there some sort of clutch feature on the cbr when downshifting from high speed on the track? You know, slipper clutch? Maybe that's messed up. Or maybe it's just an old clutch.
Is there a valve in the exhaust? Yamaha liked them on 80's and 90's bikes, but I don't remember Honda doing any back then.
My fzr400 suddenly started making a knocking sound one day. It sounded like a spun bearing and pistons whacking the head. But, it wasn't. After disassembly, it all looked fine. I figured it was that busted up generator cover making contact with the magnet or sensor or something . Too many races and crashes!
So I installed a yzf600 engine, and under load in first from a stop it makes a creaking noise. A cross between a clunk and a rattle. Kinda like the engine isn't bolted in right. Of course, it wouldn't be. The frame is a rhombus due to too many crashes!
The chain doesn't line up on anybody's fzr400/yzf600 hybrid (countershaft is offset more on the bigger bike because of the wider wheel). Maybe that's the creaking noise.
And the chain used to rattle against a heel guard bolt until I shaved that bolt down. But, it only did that when the chain was a bit loose and needed an adjustment.
Maybe your chain/wheel aren't lined up correctly either, or is loose, and the chain is hitting something.
Maybe there's something in the exhaust. When I bought the yzf600, somebody had stuffed pink fiberglass insulation in the muffler, and it was as quiet as a car. Who knows what could be lurking in yours. Maybe a rock or a broken piece of metal.
Let us know what it turns out to be.
#3
01-19-2019, 12:23 PM
It might be worth stripping the bike the bike down a little. I’d think about removing the fairings and exposing the bike a little. Something might be spotted and you can see more. You can then use a rod to your ear to have a listen around at this stage and even ride it gently. I would try to close in on the noise. Pin point it. I’d look at the clutch as well.
Seems from your description that the noise only comes in when your moving, or the bike is upright.
My experience of a cam chain issue worked the opposite of your findings. At tick over she sounded like a bag of nails but once the engine was loaded, the noise decreased but did not go away.
An engine strip revealed a broken cam chain guide.
You have replaced the tensioner, but guides can fail. You will be fighting a losing battle with your adjuster if this is the case.
Best of luck mate and keep us posted as you go.
Seems from your description that the noise only comes in when your moving, or the bike is upright.
My experience of a cam chain issue worked the opposite of your findings. At tick over she sounded like a bag of nails but once the engine was loaded, the noise decreased but did not go away.
An engine strip revealed a broken cam chain guide.
You have replaced the tensioner, but guides can fail. You will be fighting a losing battle with your adjuster if this is the case.
Best of luck mate and keep us posted as you go.
#4
01-19-2019, 01:37 PM
CCT rattle
When I manually adjusted the cam chain on my cbr600 the method was to tighten it very slightly and slowly until the rattle went away. Too tight is bad.
So, how do you know if you tightened it properly if the rattle didn't go away?
Also with the 600, the cam chain didn't rattle when the bike was cold. Only after it warmed up did it rattle.
Of course, I didn't install the manual tensioner right away, and after several hundred more miles it would rattle when cold.
Also eventually, when ignored long enough and the rattle became louder, the starter could not start the bike. I had to push start it. After installing the manual tensioner, the same old battery could then start it up.
So, how do you know if you tightened it properly if the rattle didn't go away?
Also with the 600, the cam chain didn't rattle when the bike was cold. Only after it warmed up did it rattle.
Of course, I didn't install the manual tensioner right away, and after several hundred more miles it would rattle when cold.
Also eventually, when ignored long enough and the rattle became louder, the starter could not start the bike. I had to push start it. After installing the manual tensioner, the same old battery could then start it up.
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