Engine noise GSX1100 ESD

[juantheman]

Hello to all, I have a what i belive is a 1984 GSX 1100 ESD, its a European model and has been re-painted but i,m fairly sure thats which model it is, it has the 1075cc engine.
Now the problem. It has developed a Rumbling/Grating sound on the LHS of the engine that sounds like its coming from behind the Generator cover. Its fairly quiet at tickover but gets louder as you rev it up then dissapears at about 2000 revs. Engine performance is as good as ever but the sound returns when i shut off the throttle no matter what speed i,m doing.
I took the Generator cover off( isnt that starter cog a B*tch to get back on???) and nothing seems loose but i didnt remove the generator itself.
Any ideas??? All help Gratefully recieved

[tfb]

Juan,

1. I assume you looked for metalic debris stuck to the rotor magnets, when you had the cover off? Any such debris (eg. from the starter clutch rollers breaking apart) will foul between the ends of the stator 'arms' and the rotor. And it makes noise.

2. Is the rotor securely bolted onto the end of the crankshaft? Sometimes the mongrels can come loose and the key gets mangled, etc. etc. and the whole thing flogs around.

3. Is the starter clutch tightly bolted to the back of the rotor? The three bolts are known to shear off, although if your bike is a 1984, I would expect it to have uprated (thicker) bolts here than the earlier GSX engines. Check it anyway; nothing is impossible.

4. Is the stator itself securely bolted to the inside of the generator cover? Again, the bolts can come loose, and they should have been installed with thread-locking compound. (In fact just about anything with a bolt or a nut in this area of the engine should have thread-locking compound.)

5. Your comment that the "starter cog" is hard to reinstall has me wondering, is everything alright there? Because I have never had a moment's trouble getting things back together under the generator cover... it's one of the most straightforward things in the world! So I'm wondering if everything is installed correctly in your case. Just a thought.

6. If it is none of the above, I would start to wonder about crankshaft bearings and other ominous things like that.

7. In any case, if you can't find the cause I would take it to a reputable bike mechanic and get their opinion on it... because engine rattles are a bit hard to diagnose over the internet.

All the best with it Juan.

Mike.

[juantheman]

Juan,

1. I assume you looked for metalic debris stuck to the rotor magnets, when you had the cover off? Any such debris (eg. from the starter clutch rollers breaking apart) will foul between the ends of the stator 'arms' and the rotor. And it makes noise.

2. Is the rotor securely bolted onto the end of the crankshaft? Sometimes the mongrels can come loose and the key gets mangled, etc. etc. and the whole thing flogs around.

3. Is the starter clutch tightly bolted to the back of the rotor? The three bolts are known to shear off, although if your bike is a 1984, I would expect it to have uprated (thicker) bolts here than the earlier GSX engines. Check it anyway; nothing is impossible.

4. Is the stator itself securely bolted to the inside of the generator cover? Again, the bolts can come loose, and they should have been installed with thread-locking compound. (In fact just about anything with a bolt or a nut in this area of the engine should have thread-locking compound.)

5. Your comment that the "starter cog" is hard to reinstall has me wondering, is everything alright there? Because I have never had a moment's trouble getting things back together under the generator cover... it's one of the most straightforward things in the world! So I'm wondering if everything is installed correctly in your case. Just a thought.

6. If it is none of the above, I would start to wonder about crankshaft bearings and other ominous things like that.

7. In any case, if you can't find the cause I would take it to a reputable bike mechanic and get their opinion on it... because engine rattles are a bit hard to diagnose over the internet.

All the best with it Juan.

Mike.

Many thanks Mike for a prompt response!
I didnt notice any metalic debris in the casing or stuck to the magnets, and the rotor seamed solid enough. As i didnt remove the rotor i didnt get to look at the starter clutch but the big cog that goes around the rotor seems free and noiseless.
The double cog that engages the starter motor doesnt line up with the hole that the big metal dowel goes into and i had to push the cog upwards and to the right against the starter to get the dowel in - is this normal???
While not ruling out main bearing failure, ive had that on other bikes and that always sounded like a constant low rumbling that didnt go away - unlike this noise!
The last time i took the bike to a Mechanic he declined any work saying he had been waiting for gaskets for a similar bike to arrive from Madrid for 3 months! I ordered a full gasket set from the UK on the Internet and got one in 5 days!
Further inspection is required - Does anyone have any more ideas??? 8)

[tfb]

The double cog that engages the starter motor doesnt line up with the hole that the big metal dowel goes into and i had to push the cog upwards and to the right against the starter to get the dowel in - is this normal???

Hmmm, you have chosen to describe the procedure in a way that I would never describe it... that doesn't necessarily mean anything is wrong, but it has got me wondering.

With the cover off, the 'idler gear' (I think that is what it is called) should be simply sitting in place on the dowel. That is, upon removal of the generator cover, the dowel should be located in the crankcase and not the cover, and idler gear will just be sitting on the dowel. Then, replacing the cover is simply a matter of just slipping the cover on. You shouldn't have to go through any rigmarole of trying to line things up; it should all be fairly easy to do.

Re. the noise, yet another possibility is that the idler gear may be missing a shim or two, and so that what you may be hearing is the gear rattling with too much sideways freeplay on the dowel.

I agree that with main bearing failure, you are listening for a low rumble... and as you know what that sounds like, I think we can happily discount it.

Part of the problem with engine noises is that sometimes what sounds like a rattle in one part of the engine can really be sourced somewhere else. Like with clutch rattle; it seems to come from everywhere.

While I was at it, then, I would check a few other obvious things, like the centre nut that holds the clutch basket to the primary gearbox shaft. And also the tightness of the nut that holds the drive sprocket on. Another easy thing to check while you have the clutch cover off is the oil pump, which sits behind the clutch basket.

Beyond that, and without listening to your engine, I don't think I can say much more. But let's see what others say.

Mike.

[Mikael]

The starter gear that sits behind the starter clutch rotates on the crank
through a needle bearing.

My guess is that your bearing is in bad shape, take the rotor off to have a look.
(A bad bearing will eventually ruin the crank shaft end.)

/ Mikael

[juantheman]

Thanks mike and mikael for your answers. Mike, when i removed the generator cover the dowel stayed in the cover and the starter cog fell off it but i recovered 2 shim washers one behind the cog on the engine side and one still on the dowel in the cover. i did wonder about this cog floating on the dowel but how would i check this?

Looking at the clutch basket is a good idea and while i,m at it, is it possible to tap the gear change shaft back from the LHS towards the clutch so i can change the oil seal on the gear change shaft at the drive sprocket end which is weeping slowly???

Mikael, i had a feeling there must be a bearing for the starter clutch but i dont have a workshop manual for this bike. Is there anything i need to know about taking the rotor off??? 8)

[tfb]

The starter gear that sits behind the starter clutch rotates on the crank
through a needle bearing.

My guess is that your bearing is in bad shape, take the rotor off to have a look.
(A bad bearing will eventually ruin the crank shaft end.)

/ Mikael

Good point Mikael, I think that's a better punt than any of my guesses; that needle-roller bearing could well be the problem.

i did wonder about this cog floating on the dowel but how would i check this?

You can best do this by using an accurate vernier caliper and taking a number of measurements, eg. width of idler gear cog, gap between cover surface and dowel hole edge, etc. and do the sums so that you work out what amount of freeplay would be left without the shims. Then you can work out what thickness shims you would ideally need. Obviously you want to be left with a little bit of freeplay, eg. something like 0.25mm would be good.

is it possible to tap the gear change shaft back from the LHS towards the clutch so i can change the oil seal on the gear change shaft at the drive sprocket end which is weeping slowly???

Yes indeed it is. Just need to make sure you have the clutch basket etc. out of the way, and the selector shaft should slide through. But you should be able to do it without moving the shaft anyway. Just get a sharp screwdriver, hammer it through the wall of the seal (don't go too far!), and prise the old seal out, and slide it off the shaft. Then, clean the shaft thoroughly, and slide the new seal down the shaft (a smudge of oil will help things nicely), and using a long tube spanner or something like that of the correct diameter for the seal, tap the new seal home.

Is there anything i need to know about taking the rotor off???

A manual would be a big help, but basically you will need to use a slide hammer to pop the rotor off (once you have undone the nut first of course). If you get stuck I can send you some scanned pages from my manual. In any case you will need all the relevant torque figures when you do things back up. So it's best to make a bit of an investment now, and buy a manual. It will pay for itself in no time, trust me.

All the best,
Mike.

[juantheman]

I ,ll start by investigating the bearing on the starter clutch first when ive found a puller, i agree that a manual is worth the money but that,ll have to wait til i return to the UK at Xmas. In the meantime i,ll have a go at the seal on the gear selector shaft when ive found somewhere round here that sells such things, anyone reading this thats familiar with the Spanish lifestyle will understand my problems in obtaining anything quickly.
many thanks for your help mike