Hi again folks, me again with yet another strange issue...

The bike (WM20) has developed an odd "chuffing" noise when running - when she does about 25 mph, it sounds like "chuffetty chuffetty chuffetty chuffetty"....

Had the dynamo off, not that... had the valves looked at, not that... had the clutch apart, not that... nothing seems to be coming from the engine itself & the bike is running otherwise 'properly'...

Had a new mag fitted recently, and initially the bike was running fine with it, but then, the chuffing started...

Could it be the mag?

Worried now as she sounds like Thomas the Tank Engine when I'm out and about.... Bike currently V.O.R till I figure out what it is.

I will TRY to get some video of it later if no one can think of the problem

Cheerz
Ian

email (option): fozzie001@hotmail.com

Hello Ian,

If the noise is speed related,
("when she does about 25 mph") rather than RPM related,
Then maybe the problem is within the wheels / drive train?
Can it be that in that speed, for some reason,
Something is scuffing against the mudguard or something like that?
If you have rear stand, maybe you can run it withe the wheel up
And look for the sound?
If it was coming from the engine, the frequency of the noise was high.
If you hear it about twice a sec, it probably comes from one of the wheels,
I would say.
Are the 3 screws securing the rear wheel fasten properly?...
It mat be a good idea to look for scuff marks inside the mudguards/chain cover.

Hope that helps...

Noam.

Ian,

When the engine is running 30 mph. turn it off.

John

email (option): john.kater@chello.nl

I suspect the magneto oil seal leaking as you say had new magneto fitted recently.
Dave T

Thanks folks. The sound stops when engine not running so maybe the cure is to not start the engine lol :-)
Seriously though, the chuffing is rpm related but at 25 mph (ish) it is easy to hear as the road noise isnt too loud.
It is very noticeable when running close to walls/building as the sound reflects back.
There is no obvious oil loss apart from a drip from primary chain case (cork seal leak).
Would anyone think it is a magdyno shimming related issue?
Ian

Hi Ian, Are you sure the exhaust pipe is fully into the head! Just a guess Bryon

Head gasket.

Hi guys,

After further investigation and a fair degree of frustration, I took the dynamo off again, but this time I swopped it for one that I had recently refurbished (I've got 7 sitting here now!) and VOILLA!! The wierd chuffing has stopped doing it's thing!

What is odd is that the dynamo I took off was recently refurbished (not by me) and, when turned by hand it rotates freely on the bearings and makes no unusual noise...

Beats me!! I sometimes get the feeling my bloody bike has a ghost lurking in it somewhere!

email (option): fozzie001@hotmail.com