Engine noise

[stevie]

Evening all

Wonder if you knowledgeable folk can help me out? Ever since I have had my  1980 r65 (4yrs) there has been a noise emanating from the engine at tickover which I would describe as a sporadic "clunking", which disappears once a few revs are applied. I know this may sound like alarm bells, i.e big ends etc but I am not sure if this is the case. The old girl does'nt use any oil, and although she smokes at first if she has been laid up for a while this soon disappears when warmed up and the bike runs fine pulling reasonably well etc. It could be coming from the air filter area. Is there some sort of "flap" etc which could be the culprit. As ever any ideas appreciated.
Regards Steve.

[airhead]

Sounds to me like the dreaded loose rivets for the ring gear to the clutch carrier syndrome, not too uncommon.
If it is you will have to see to it before the ring gear drops, embarrassing if done at speed!!
Best way is to the drop the gearbox and pull the carrier/ring gear. Otherwise accessing the ring gear via the starter motor, or even limited access via the timing hole plug, may tell if the rivets/gear are loose.


Bill...................;-)

[mikethebike]

See if the noise disappears when you pull the clutch.  If it does, it's probably slop in the gearbox.  My old H***a used to do it.  It ran like that for 5 years and never got any worse.  As my old grandad used to say. If it aint too noisy, let it develop a bit!

[samc]

Sounds to me like the dreaded loose rivets for the ring gear to the clutch carrier syndrome, not too uncommon.
If it is you will have to see to it before the ring gear drops, embarrassing if done at speed!!
Best way is to the drop the gearbox and pull the carrier/ring gear. Otherwise accessing the ring gear via the starter motor, or even limited access via the timing hole plug, may tell if the rivets/gear are loose.


Bill...................;-)

"dreaded loose rivets"....  this does not sound good. details?

[stevie]

Hi fellas

Just been out and started the bike. With the clutch pulled in the noise does'nt disappear. However in retrospect I would'nt now say it was a "clunk". Listening carefully the noise definately is coming from the air filter end, coud it be the engine breathing so to speak, as sounds kind of like a "throaty echo", definately not metallic, could it be an idiosyncrasy of my bike? Hope my explanation makes some kind of sense.

Regards Steve.

[Justin B.]

Maybe the crankcase breather valve?  The ones on the older bikes can be somewhat obnoxious.

[Barry]

Sounds like a turkey gobble ?  I also had that noise from the engine breather. The accepted cure is to replace the early spring disc breather with the later reed valve but it may not be easy to get the old valve out without the aid of a slide hammer. I read that the factory recommended drilling a 1/16 inch hole through the fibre disc so I tried that first. Result near silence!  I get one gobble occasionally on engine shut off. I can live with that and call it character.  Oil consumption is negligle over 1500 miles so there doesn't seem to be a down side.


Barry

[stevie]

Barry, you've named that tune in 1!!! Was this an easy fix? Although ff it's not doing any harm as it is I may leave well alone. like you say character! However if I ever come to sell the "turkey gobble" may scare someone ignorant to BM ways off.

regards Steve.

[Barry]

stevie,  the job is easy enough. You will need to remove the tank and the starter cover. The breather lives under a small domed casting on the right hand side with a hose leading into the air filter housing. If you have the early type breather (mine is a 79 R45) the breather valve will be a spring loaded paxolin disc. Remove the circlip noting which groove it was located in probably the top one. After removing the disc take care not to drop anything in the crankcase.  Drill a 1/16 inch hole about half way between the centre hole and edge of the disc and reassemble. Took me less than an hour from start to finish and was very worth while as my turkey was diabolically noisy.  It could have been one reason why the previous owner had only done 6200 miles in 28 years. There were other reasons. If anyone has noisy forks that clunk on sharp edged bumps I'll do a post on how I cured mine.


Barry