Strange new noise......(update).

[oobyscoot]

Hello all,

My GS has developed a strange new noise coming from the front sproket area.

Its a sort of knock knock knock, but only when coasting. The knocking goes away when the engine is under load or under engine braking. As soon as I pull the clutch, the knocking comes back.

I have checked the slack in the chain and it seems about right. I have also oiled the chain. Odly though, I lubed the chain when I parked her up last night and noticed the noise first thing this morning. She still rides ok and got me the 40 odd miles to work without any issue (other than the noise).

I am out of chain lube (normally use the rattle can stuff) so intead I used some 80w motor oil, could this be the problem? I will clean it off this evening and try that, but I cant see why that would make it knock myself.

Any suggestions welcom.

[ben2go]

Try cleaning and relube.Check your sprockets.They should be flat on the end of the teeth.Pointed and curved teeth are bad and need replacing immediately.Usually knocking/popping sound means that the chain links are binding and not wanting to bend around the sprockets.It maybe time for a new chain.If you decide to replace it any 110 link 520 o-ring chain will work.I prefer a clip type master link,some prefer the rivet style master link,while a few like the original continuous chain with no master link.

[oobyscoot]

The chain was replaced recently, About a month ago. Its a heavy duty x-ring type. sprokets were OK then, (as checked by the shop). I do a lot of miles so I buy only good chains as I get through the cheapy's in no time at all.

Thanks for the sugestion though. Do you think it could just be the wrong lube doing this? I remember reading that you can use a heavy weight motor oil on the chain, but I think it was 40 or 50w, I used 80w as I had some at the time.

This is a bad time for a new noise as it is MOT time next week.

[sledge]

What sort of condition are the splines in?

[oobyscoot]

What sort of condition are the splines in?

Can I have that in laymans terms please?

Is a spline the thing that the front sproket goes onto? If so, It was all good a month ago when the shop checked it out. I can recheck though, what are the signs to look for?

I have always taken my bikes to the shop until recently but have decided to do all the spannering myself in an attempt to keep costs down so I am a relative novice appart from normal servicing.

[ohgood]

What sort of condition are the splines in?

Can I have that in laymans terms please?

Is a spline the thing that the front sproket goes onto? If so, It was all good a month ago when the shop checked it out. I can recheck though, what are the signs to look for?

I have always taken my bikes to the shop until recently but have decided to do all the spannering myself in an attempt to keep costs down so I am a relative novice appart from normal servicing.

If you didn't have your front cog changed when the new chain was put on, they're both junk now.

That hiccup you hear when there is no load on the chain is the miss match of the cog to the chain.

Sorry.

Splines = the square grooves that are broached into the center portion of your cog, and milled onto the output shaft taht the cog rides on.

The only time I've had noise from a chain was:

Too much slack

Chain and Cog beating each other to bits because it was a new chain on an old cog.

Hope I'm wrong.


***********

edit, I neglected to mention if you haven't put ALLOT of miles on that new chain yet, you can still order a replacement FRONT cog and it will be fine. The rear cog will likely never need replacement.

"Sharks tooth" is describing the teeth on the cogs. They should have a flat at the very end, along with a chamfer on either side. IF that is gone, your cog is definitly 'shark toothed' and junk. Make a clock out of it, but don't use it on your bike

[oobyscoot]

Thanks ohgood.

I have just ordered a new front cog. Only £5 so gotta be worth a try.

[ohgood]

Thanks ohgood.

I have just ordered a new front cog. Only £5 so gotta be worth a try.

Only ? So, that's like $6,000 USD now, right ?   I'm kidding. Hope it works, make sure you get the right one. Some have shoulders, some do not. IIRC the 89-97 (or is it 94?) models don't have a shoulder, whereas the 98-0x's have a shoulder on the cog. I should have mentioned that. The supplier should be able to sort it out.

The non-shoulder type will rattle on the splines some. I tried it, didn't work. Ordered a shoulder type for my 98 and it was fine afterwards.

[oobyscoot]

Bugger, Ordered the wrong one.

Mines a 98 and I ordered the early one. I should have read that in the first place.

Thats a fiver down the drain then. I will have to order another one.

[oobyscoot]

crisis averted.

I just rang JT's Motorcycles and explained that I ordered the wrong one online, the guy said no problem, and as it turned out was about to put the one I had ordered into despatch so he just swapped it for the one I actually want and promised I would have it tommorrow morning. 

Thanks for the heads up Ohgood.

As for the customer service at JT's, I think it deserves a plug.

WWW.JTSMOTORCYCLES.CO.UK   or    01792461776 for any mail order bits in the UK.

[Jerka]

Let us know if that fixes the noise.  Thanks.

[Trwhouse]

Hi there,
This is a good experience, even if it is a slight pain in the neck.
This is an example of why you should always replace the sprockets -- some people say at least the front sprocket, but I always do both because I'm a stickler for not wanting problems with it later -- when you replace a chain.
As someone said above, the chain and sprockets wear together in a pattern and replacing just the chain means the new chain will get quickly damaged by sprockets that have probably been worn funny or in specific patterns that came from their original, now worn-out chain.
I hope the front sprocket was caught quickly enough, and that you are back on the road on the way to your MOT right away.

Best wishes,
Trwhouse

[oobyscoot]

Let us know if that fixes the noise.  Thanks.

Will do Jerka. I will have a bash at it tomorrow afternoon.

Looks like the big bike is coming out for work in the morning.  Dont want to ride the GS before I get the new sproket just in case I wreck the new chain.  Allthough I am at the office now so I will have to ride it home tonight.

[astroaru]

Hello all,

My GS has developed a strange new noise coming from the front sproket area.

Its a sort of knock knock knock, but only when coasting. The knocking goes away when the engine is under load or under engine braking. As soon as I pull the clutch, the knocking comes back.

I had similar issues. if the noise still does not go away, I would recommend that you open your left side crankcase cover. Don't expect surprises 
My starter driven gear had an out-of-plane wobble which had this weird noise.

[sledge]

Hello all,

My GS has developed a strange new noise coming from the front sproket area.

Its a sort of knock knock knock, but only when coasting. The knocking goes away when the engine is under load or under engine braking. As soon as I pull the clutch, the knocking comes back.

I had similar issues. if the noise still does not go away, I would recommend that you open your left side crankcase cover. Don't expect surprises 
My starter driven gear had an out-of-plane wobble which had this weird noise.

Agreed............conclusions are being jumped to here without any sort of inspections or evaluations. The sprockets were deemed servicable 1 month ago by the shop who carried out the chain replacement.

[ben2go]

Thanks ohgood.

I have just ordered a new front cog. Only £5 so gotta be worth a try.

Only ? So, that's like $6,000 USD now, right ?   I'm kidding. Hope it works, make sure you get the right one. Some have shoulders, some do not. IIRC the 89-97 (or is it 94?) models don't have a shoulder, whereas the 98-0x's have a shoulder on the cog. I should have mentioned that. The supplier should be able to sort it out.

The non-shoulder type will rattle on the splines some. I tried it, didn't work. Ordered a shoulder type for my 98 and it was fine afterwards.

94 is when the sprocket got the shoulder.

[oobyscoot]

I took the front cover off last night and spun the wheel, the front sproket seems to have 1 badly hooked tooth, but the others are all OK. I could actually see the chain snagging on that one tooth everytime it came round. I took the chain off and removed the sprocket to check the Splines (i think) and they were square on the shaft but a bit sort of pointy and odd shaped on the sprocket, this was allowing the sproket to move (rotate) slightly on the shaft.

I am allmost convined this is the cause as the clunk clunk coencided exactly with 1 revolution of the sproket.

Thanks for all the input guys, I will post the results as soon as I have the new sproket. Fingers crossed the chain has survived.

Oh well, lesson learned. But why did the shop not recomend changing both, they could have had an extra fiver off of me.

[sledge]

I took the front cover off last night and spun the wheel, the front sproket seems to have 1 badly hooked tooth

Unusual........I have lost count of the number of sprockets with worn teeth and splines I have seen but I have never seen one with just 1 tooth worn............... any chance of pics?

[oobyscoot]

Sure. I will take a picture of it when I do the job hopefully later today.

There looks as if there are some signs of wear on all the teeth but most still had a flat end on them as (I think) ben2go described in an earlier post, but one tooth seemed a little more of a hook shape, looks allmost bent over at the end, that was the one I suspect was making the clunk as the clunk came everytime this tooth was coming out from the chain (if that makes sense) where the chain leaves the sprocket at the bottom.

Turning the wheel by hand, I could actually feel quite a prominent clunk to it as well.

I will post a picture later (stuck in the office just now) but it wont be the best as the only camera I have is my phone.

[ohgood]

Sure. I will take a picture of it when I do the job hopefully later today.

There looks as if there are some signs of wear on all the teeth but most still had a flat end on them as (I think) ben2go described in an earlier post, but one tooth seemed a little more of a hook shape, looks allmost bent over at the end, that was the one I suspect was making the clunk as the clunk came everytime this tooth was coming out from the chain (if that makes sense) where the chain leaves the sprocket at the bottom.

Turning the wheel by hand, I could actually feel quite a prominent clunk to it as well.

I will post a picture later (stuck in the office just now) but it wont be the best as the only camera I have is my phone.

1) I have no idea why they didn't suggest replacing the drive cog. They could have made another $50 off of you (parts AND labor) for 3 minutes worth of work. That was dumb of them letting you ride out without making your bike as safe as possible.

2) Hmm, sounds like you were past 'sharks tooth' and into 'hookem high' zone. Basically that means your chain and front cog were waaaaaaaaay gone. The new chain likely broke that tooth off. Think about the chain being down in th 'hook' portion of the valley, and a change in torque/speed. I've only seen bicycle cogs that had interesting breakage like this before, motorcycles are still very new to me.

When your pictures are up, I'm gonna predict it's a scary looking thing.