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Engine noises again

Could people give their opinions on what pre ignition or detonation problems actually sound like on these side valve engines?
When pulling hard, my bike will occasionally produce a loud metallic tinkling sound, not as harsh as tappet noise. (Tappets are set correctly). Backing off the ignition will sometimes help. An alloy head is fitted.
I've looked in the technical section here & elsewhere but can't find a reference to the specific sound. I'd like to have an idea of what the problem actually is before I start looking around.

Re: Engine noises again

Hi Bob

I don't have an alloy head on mine, but pinking sounds like a light tinkling noise. As you say, momentarily retarding the ignition should make it stop. You usually notice pinking when going up steep hills, particularly if you have camping gear on.

If it isn't an audible knock that gets faster as you accelerate, then it shouldn't be a bottom end problem. However, depending on the condition of the piston and liner, you may be noticing a bit of slap or slight wear in the small end bush.

Describing Knocks and noises is quite a personal thing and difficult to pin point in written form. However, if the noise is a tinkle, happens only under load and stops if the ignition is retarded, then hopefully it is just pinking.

Regards

Pat

email (option): sacombsashtrees@hotmail.com

Re: Engine noises again

Hi Patrick
Thanks for the reply. Yes, describing engine noises in print is a personal thing, but a "light tinkling noise" is a good description of the problem. And retarding the ignition definitely helps. So I'm fairly sure it's pinking.
Bob

Re: Engine noises again

I was getting lots of pinking noises from my WM20 (600cc) and double-double checked the timing and even fitted new cams in case I was mistaking the noise.

I'd been running the bike with a solid copper head gasket that came from somewhere? that required quite a bit of filing to the holes to get it to fit. When I eventually removed the head, I found a small crack in the gasket between the bore and one of the head bolt holes. I refitted one of TT John's gaskets and it's doesn't pink anymore. Ron

email (option): ronpier@talk21.com

Re: Engine noises again

In my 16h pre ignition didn't result in a light tinkly noise, it sounded like a hammer. And yes it went away when I retarded the ignition. I fitted a made in India Bosch M5AC and no more pre ignition. Actually that's the only plug it likes.

email (option): jeremy@clogmaker.co.uk

Re: Engine noises again

Thanks for all these replies folks. From what you say I think it's pinking I can hear. The engine did this yesterday when pulling hard up a long hill & retarding the ignition fixed things a treat.
Unfortunately any further experimentation's been put off by something letting go, clouds of blue smoke everywhere. The engine had been guzzling oil lately so I hope it's just the rings.
I doubt the noise I mentioned has anything to do with this catastrophe as it has occurred when the motor's known to be in good nick.

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