Gearbox(?) Clatter at higer RPMs

[ajbessinger]

Hi there folks,
I've got an 83' R65ls that I recently picked up for pretty cheap. Heres the issue though, it's got quite a loud clattering noise that I've noticed, seems to come on somewhere between 5000-5500 rpm, below that, it seems perfectly fine... Sounds to me like it's coming from the gearbox.

I'm new to airheads, but know that the transmissions are known to be a bit clunky, but this definitely does not sound like anything remotely close to normal to me...

I've tried searching to see if I could find anyone else with a similar issue, but I haven't been able to find anything.

[Rob Frankham]

There's not enough information there for an informed comment I'm afraid. There are some things you could try to get more data on the issue, for example, does the noise change when pressure is put on the clutch lever? Does the frequency of the noise change with engine revs or with road speed? Does it occur specifically in one gear or equally in all gears? Does it get worse, better or stay the same dependent on power applied (i.e. is it worse if you are going up hil, down hill, on the level or stays the same). If you have the bike stationary and out oif gear and take the revs to 5000 (briefly and carefully) does the noise occur?

That being said, it's likely that you are faced with stripping down the drive train to diagnose the problem. There are three areas (with an option on a fourth) to bear in mind if the sound is coming from the gearbox area:

1. The driveshaft... are the connecting bolts present and tight. If they have been mishandled in the past, they can become loose, break or even fall out and that can definitely cause untoward noises from that area. Is the Hooke joint at the front of the shaft sound.
2. Clutch... There are several parts of the clutch that can and do fail. In particular, are the cover plate securing bolts on place and tight? Is the thrust bearing good?
3. Gearbox... If the input shaft or the output shaft bearings are bad, you can normally tell by pulling the relevant shaft up and down... but anything else will need a strip down to find.
4. With an option on... Engine... with the engine and gearbox close coupled, it is quite easy for sound to appear to be coming from one area when it is really originating from another. If you can reproduce the noise while stationary, use a stethoscope (or screwdriver etc. etc.) to try to fine down the source of the noise.

Sorry, there's no easy answer to this one... you'll need to do some work to tie it down.

Rob

[SteveD]

Pinging?

[ajbessinger]

Well, now I feel dumb . I did some poking around, and it turns out the bolts on the front cover weren't tightened all the way.
Apparently the vibration frequency of the motor between about 5000-5800 from was just right to make the thing rattle aroibd and sound like a tin can full of rocks! Super weird that it didnt make any noticeable noise at any other RPM.

[Rob Frankham]

Well, now I feel dumb . I did some poking around, and it turns out the bolts on the front cover weren't tightened all the way.
Apparently the vibration frequency of the motor between about 5000-5800 from was just right to make the thing rattle aroibd and sound like a tin can full of rocks! Super weird that it didnt make any noticeable noise at any other RPM.

Oops... ... we all do it, at least you weren't to precious to admit it.

One thing to take from this is now easy it is for a noise from one part of the machine to seem to be coming from a completely different area. Sometimes makes diagnosis very difficult.

Glad it was something simple and easily fixed.

Rob

[SteveD]

I chased a rattle on the RS fairing for a while. It was the front cover! Not the first, won't be the last.

Welcome,btw.

[MikeL46]

The first rule of troubleshooting is to look where the last person worked.

Second rule is to check the easy stuff first.

I wish I knew the third rule.

Mike