Mysterious noise

[coolhandgarreth]

I've been trying to find the source of a intermittent rattling sound that has me concerned since it seems to be coming from inside the crankcase. I'm hoping it's something like worn bearings or a loose baffle in the exhaust, but the sound is all I have to go on. I noticed it first after getting caught in the rain, which may just be coincidental. The only other thing that could be related is that occasionally, on start-up, it sounds like the starter is stripping gears. At this point, everything is completely operational, starts fine, sounds normal at idle, shifts fine through all gears. Seems like the sound is most noticeable when letting off the throttle.
If I had to guess, I'd say something got broken off and is being kicked around in the crankcase. I drained the oil out of it and did find some very fine metal shavings on the plug.
Any wisdom worth sharing would be most appreciated.

 

[user_deleted]

If I had to guess, I'd say something got broken off and is being kicked around in the crankcase

not impossible highly unlikely as a small piece of piston skirt for example would rattle all the time. very fine metal shavings on the drain plug magnet are normal for both engine oil and primary oil drain plugs.
you did not mention year, 9 or 12, model, mileage....really not much to go on....but if a 12 an easy check and noise elimination would be the interactive muffler valve. they can become loose and rattle.

 

[coolhandgarreth]

Right, 2009 scg, 10,500 miles. The muffler valve has been disconnected since previous owner installed a race ecm with the stock muffler. I opened up the valve and used a series of zip ties on the loose cable end to hold it in the open position after reading a post on this forum that suggested that. I'll check that.

 

[coolhandgarreth]

So I reconnected the muffler valve and continued to hear the sound. It's a dull clacking sort of sound that does seem to be coming from the right side of the bike. I'm wondering if it might be a wheel bearing or the idler arm bearing going bad. I rode to the top of a hill and coasted down with the engine off and in neutral. Same sound. I might have contaminated one of those bearings when I was washing all the road crap off the bike after getting caught in the rain.

 

[d_adams]

Could be the transmission output shaft bearings. I hate to say it, but mine is making a ringing sound, both loaded and unloaded (under power or not) and makes noise even when it's off, more like a growling when I roll the wheel on a rear stand. Haven't pulled the belt to see if it's just the pulley yet, but I'm kinda doubting it. Only 1k miles since I bought it last year, 500 of it at Homecoming this year.

I wasn't really planning on doing any work to this bike, even though I'd gotten it for a decent price.

 

[Theycallmecrash]

Loosen the primary chain. Mine makes by your description same sound under acceleration if its too tight.

 

[d_adams]

[sad]

 

[Theycallmecrash]

Thats, a lot intense.

Its not that bad to split the case, labor wise. $$$ thats a different story

 

[coolhandgarreth]

I checked the primary chain. Didn't appear to be too loose. Thankfully, my bike isn't making that grinding sort of noise. It's much more intermittent, at this point anyway. I'm thinking I'll replace some of the less expensive parts first and hope to resolve the problem before it gets to something like the transmission output shaft bearings.

 

[Theycallmecrash]

Checking and actually making an adjustment are 2 different things.

Stare at the bike a little longer and harder bet eventually itll fixs itself.

 

[coolhandgarreth]

Your first suggestion was better than your second, Crash. By checked, I meant that I actually measured the primary chain tension as well as I was able to with a tape measure and I experimented with several different tensions with no improvement. If it were possible to stare the bike back into proper running condition, this forum wouldn't be worth near as much as it is. No one would be looking here for useful insight to bike problems.

 

[djs2k2]

Just checking because this could happen! You wouldn't happen to have a bell would you. Just had to ask not being a smart @ss but out bikes vibrate and if you have a bell you have a ring.