grinding noise in low rpms when in gear

[firechicken]

I've recently noticed that my kat (2000 gsx600f) is making a grinding noise in the low rpms's of every gear. I did a search and didn't find much so it must not be a common problem. I'll describe it to the best of my ability and hopefully someone can chime in with an idea.

First of all the bike has 16,000 miles and runs great other than the noise, it shifts confidently and pulls strong through the rpm's. The noise sounds like it is coming from the gearbox but it is hard to be certain when i'm wearing a helmet. It is a quiet but notable chunchy grindy sound when i take off and when i accelerate through the lower part of any gear...most noticeable in the first 3 fears. it completely stops at about 4500rpms. it seems to be a little louder when there is more strain on the bike, if i'm starting on a hill for example. it isn't the front brake and definitely makes the noise during and after grabbing the clutch. I have read that chains make a similar noise and i'm hoping that is the case but I get a feeling that it is internal. I have never experienced anything like it so i could use all the advice i can get. I recently adjusted (tightened) and oiled the chain, how can i test the chain to see if it is the culprit?


*by the way it is a naked bike so it isn't a fairing rubbing situation.

[HighRisk]

Even being a naked bike something could be rubbing, I would try checking any bits of plastic like the housing around the headlights, or even metal vibrating at the right frequency to make a noise in the lower RPM. Worth a shot to take everything that you've played with recently and tighten it down, especially if it doesn't make the sound in neutral and only at speed.

[ZukiFred]

I would start with checking chain and sprockets myself.

[Kreylyn]

Remove the sprocket cover. Inspect both sprockets for any deformity or wear. Carefully keeping your fingers away from them, spin the rear wheel if possible and observe how the chain rolls on the sprockets as well. Any jumping, catching or jerking is a sign of a problem. Finally you can pull on the chain at the center far back side of the rear sprocket. If the chain can be pulled away from the sprocket, that is also a sign of wear on the chain.



The service manual (free, in the KR wiki, link above in the blue bar, download it!) can tell you the measurement for the chain to do verify it's still in spec as well. You measure 21 pins and there is a certain length that = excess wear.

Google image search "sprocket wear" for lots and lots of pics and comparisons of what sprocket wear looks like and how to see if it is.

Replace sprockets and chain if you find wear.

Krey

[GSXFJim]

Good sprocket top, bad one on the bottom... If your sprockets look like the bottom one, time for a a new set of sprockets and a new chain. Avoid the urge to buy cheap chains and sprockets, remember you get what you pay for. A number of members hare have learned the hard way and had to replace chains after only a short period of time.

[KAT TOY]

my RK xring chain has 40K+. lubed after ride. kept slightly loose.

[maniac1886]

+1 on the chain/sprockets

[firechicken]

thanks for the replies everybody. I didn't want to pull the cover off the front sprocket because it looked like a B**** but it actually wan't that bad. I put the bike on the secondary stand and rolled the wheel around and there is definitely some grabbing going on there. the chain is well lubed but it is just worn out, i can pull on the link on the back of the rear sprocket and seperate 3 links from the sprocket....no bueno. the sprockets are starting to get chewed up on the tips of the teeth, i've seen worse but they should be replaced. I could probably keep using them with a new chain but i'm just going to replace everything together, i want to bump it up a tooth on the front sprocket for more convenient highway cruising anyway. I have about 1.5-2 inches of slack in the chain when the bike is on the ground. Until i replace the chain would i be better off loosening the chain up a little bit? tightening it? Is there a cheater way to adjust a warn chain to make it a little less grabby till a replacement comes? I'm not optimistic but maybe someone has fiddled with such things before.

[maniac1886]

Thats a dangerous place to be. Your life could be on the line. That chain snaps and you're gunna be bummin. Ive seen chains snap and the rear tire lock up. Wouldnt wanna be that guy at 70-80 mph...

[shpielers]

thanks for the replies everybody. I didn't want to pull the cover off the front sprocket because it looked like a B**** but it actually wan't that bad. I put the bike on the secondary stand and rolled the wheel around and there is definitely some grabbing going on there. the chain is well lubed but it is just worn out, i can pull on the link on the back of the rear sprocket and seperate 3 links from the sprocket....no bueno. the sprockets are starting to get chewed up on the tips of the teeth, i've seen worse but they should be replaced. I could probably keep using them with a new chain but i'm just going to replace everything together, i want to bump it up a tooth on the front sprocket for more convenient highway cruising anyway. I have about 1.5-2 inches of slack in the chain when the bike is on the ground. Until i replace the chain would i be better off loosening the chain up a little bit? tightening it? Is there a cheater way to adjust a warn chain to make it a little less grabby till a replacement comes? I'm not optimistic but maybe someone has fiddled with such things before.

I'd recommend going down 2 or 3 teeth in the rear instead, getting a larger front sprocket requires some slight modding to fit. Doesn't sound hard to do, but why do extra work when you can get the same results by doing something else? This might be useful reading for you:

http://www.motorcycleanchor.com/katana/Katana_sprockets.html

2" of slack is really loose. If youre going to keep riding until you get parts in, be easy on it. Not sure if adjusting it to proper tension is helpful or harmful at this point though.

[GSXFJim]

...i want to bump it up a tooth on the front sprocket for more convenient highway cruising anyway.

What are you trying to accomplish by this? You're not going to change the gear ratio much.

If you are set on changing the final drive ratio, I'd stick with the 15t c/s up front and drop a tooth or two in the back, 16t puts the chain close to the clutch actuator rod and a sprocket cover mounting point will need to be modified. Stock is a 15/47, you could do a 45, altho you'll be giving up some acceleration, remember these engines are made to rev high, you're not going to hurt it.

If your chain and sprockets are that worn, I'd not ride it, if it fails it could be disastrous. Don't cheap out on parts because (insert excuse here), it could be the difference between riding again and never being able to ride again.

[maniac1886]

VOLAR IS THE DEVIL!!!! lol