Chain noise

Have a look to check the front of the chain guard hasn't come loose and is rubbing against the chain...
 
The chain adjustment sounds too tight. An inch with the bike unloaded quickly goes away when you are sitting on it and goes negative over bumps. That is really hard on the output shaft and bearings. An unevenly worn chain will make all sorts of odd noises and can cause a cyclic vibration at certain speeds. I'd try loosening the chain and see if the noise changes, might be time for a new one.
 
To get the drive chain precise for once and for all;  Remove the shocks and lift rear wheel till gearbox output shaft, swingarm pivot and rear axle are in line.  Adjust the chain with the wheel in this position for about 10-15mm slack at half-way its length, while turning the wheel and checking for tight spots.  Replace shocks and note free play when the bike is on the centre stand.  Write it down, etch it on the kitchen table, chisel it into your garage floor, whatever... :D  No more guess work from then on.  You will probably find that the chain will rub a bit at the swingarm pivot, fit a slipper if it bothers you too much.

Primary noise can be loads of things.  Knackered chain, incorrect chain tension, perished/hardened cush drive rubbers, worn clutch basket, worn clutch hub, loose hub on the mainshaft.  Only tearing down the entire primary drive will reveal the true cause/s.  In very rare cases, the oil pump drive can be at fault if the drive gear on the crank has been replaced with an incorrectly calibrated item.

piet
 
Okay. Thanks for all this. Bigger  day in the shed than yesterday, working through all these suggestions. The bike has an unknown mileage (MPH speedo says 000000), was bought from a guy with a broken ankle and a divorce suit who said it hadn't started for a while. From the condition of things it might have been a few decades.
No State transport departments have any record of it so I guess it must have been a private UK import. Probably one of Ronald Bigg's guys, who then died and after his estate slid it to another mate in a blood settlement, the bloke with the angry wife got hold of it and broke his ankle trying to leap from the 2nd floor verandah. Anyhow it's been a few years since I got hold of it and began working through it. It's plainly had a hard life, but when I got it going a couple of months ago it rode beautifully and has been going harder and harder since. I haven't been into the motor yet but I'm thinking about old rubber cushions now, o rings and the like, so maybe it's time. i'll let you know.
Thanks everyone.
 
Is it in the number range for dud crankshaft bearings? If so, has it been sorted?
 
Yes Davo, it's plumb mid range and that thought's been niggling at me too. However, it's had a hard life, lots of signs of that, including a wired sump plug and the wear on the swing arm tube. So I think it must have done enough to be outside that worry zone now. As well, the crank bearings seem very quiet. i've revisited the drive chain and it's set correctly. Now I'm focussing on the primary chain side of things. It sounds to my ear like a chain noise except i only hear it when the bike is moving. Crook bearings can sound like chains can't they?
 
when the crank bearings failed on my 79 it sounded like a clatter noise going on
rode it back to Brisbane from Gladstone, had no choice, to far to push it
started of nursing her along but closer I got to Brisbane the higher the speed became  :o
majority of the balls from the middle mains were in the bottom of the engine, if you dropped your oil strainer you should be able to find some with one of those flexible magnet deals
should let you know if that is the issue


 
When mine failed at 140kmph it was instant clank,then nothing, engine dead, cam chain jumped, two severely bent intake valves and a buggered cam. Had to break the valve heads off of one  to release the almost fully compressed spring  to disassemble. The good old days!!

Stu
 
You must log in or register to reply here.
Back
Top