Spent a nice long day on my 94 GS today...halfway through ride the engine developed a metallic rattling sound whenever I gave it throttle. Most noticable in 3rd gear around 5000rpm but there pretty much constantly in all gears. :x
Bike is running normally otherwise.
Anyone have a guess what this could be?
Thanks,
Sean

did you check your oil?

any loose parts on the bike?
maybe your exhaust bolts came loose and now are making noise

i went on a tri-state ride today, when i would stop, fuel up, when i would restart id hear tick, tick, tick, then alls fine? would rune fine, btw 4900 mi. on it (valve clearance?) :dunno:

Good question.  My '96 does it between 3500 and 6000 rpm, like turning a switch on and off.  We're not the only ones, either.  On a similar thread, it was tracked down to a valve tappets rattling inside their buckets in the head.  The solution in that case was to replace the head.  However, it's possible the noise we're describing is coming from different sources (piston slap or crank, connecting rod, or counterbalancer bearings).

yea, all the mice in there are scratching wanting to get out.
OK cam chain tensioner, valves clacking, ad intake manifold leak... all make such noises.
Cool.
Srinath.

I don't want to scare you, but since you say the sound developed, and you describe it as metallic: could be one of the plain bearings going bad (crankstaft, balancer shaft, rods) Check oil level (because that's usually the original cause of such a failure). Drain some oil and look for bits of metal in there. If you do find metal it could be one of the bearings and you could be in for an engine overhaul.

But then, the GS's engine does have quite a slew of mechanical sounds that are perfectly normal.

Thanks for the replies,

I did check oil, (both a couple days before this sound started and afterwards) The level is normal, and the oil on the dipstick looks clean.

Guess I'll do an oil change soon to see if anything shows up when I drain more oil out.  Might be time for a visit to the shop.  :dunno:

One of these days I'll have a garage/tools to take the thing apart and start learning a thing or two about the engine!

If I had to guess I would say cam chain is rattling.  You may need to replace the cam chain tensioner (can it be adjusted?)  CBRs are notorious for this type of problem and I experienced it on my bike.  Definitely characteristic that it only rattles in a certain RPM range.

ASLAM.

Maybe you got a Cicada in your bike somewhere?
:mrgreen:

Quote from: GRUany loose parts on the bike?
maybe your exhaust bolts came loose and now are making noise

That's what I was going to ask.  On my bike the situation in the picture below resulted in rattling at around 5,000 RPM in any gear.



EDIT: Changed link from sisna.com to bbburma.net