And while we're on it, my MC28 motor has a clicking noise coming from the top cylinder when cold. Im sure it is powervalve related because, at idle and the pulley closes the PV you can hear the sharp rapid clicking and as the pulley opens the PV the noise goes away. If you hold your finger on the PV shaft, you can feel the vibrations of the clicking. It does not appear to come from the bottom cyl. The noise goes away as the motor warms up. Could someone please confirm my worst fear that the PV is contacting the piston/rings? Would have instead thought the noise would get louder/worse as everything got hotter/expanded and closer together. Any thoughts please?

Thanks very much
Richard

It would have to be seriously buggered for the RC Valve to make contact with the piston... we're not talking Suzuki engineering here!!

It could be excess play in the assembly allowing the valve to tap on its seat a little. Certainly sounds like you should pull them out and inspect everything.
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Andy.
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Thanks Andy. Ive only noticed today it because I was changing the antifreeze and gearbox oil and idled it to get the bubbles out. Im sure that if I pull the pipe off I can get the valves out without taking the barrel off.

Have you used your screwdriver stethescope to pin point the noise?
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MC21SP Plaything
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Had a few RC valve related clicking noises. Worn shafts or too slack adjustment was the culprit.

Thanks guys for your posts. What is a screwdriver stethescope? Whos taking the piss?

no mate no-ones winding you up (lol)
place the blade of the screwdriver where you think the noise is coming from then place your good ear on the handle the noise is then amplified and easier to pin point.

Thanks guys, I think it was as Andy suggested, perhaps the RC vibrating on its seat in the closed position a little. Took the head off, no evidence of piston contact, re-assembled, readjusted the RC valves, fired it up and presto it seemes to be fixed.

I used my stethoscope on Saturday evening to diagnose a whining waterpump bearing on an MC28.

An invaluable tool.

Trouble is that it meant I had to miss out on a few shandies with Andy and change the bearing.

I'd like to say you were missed Matt, but something else was keeping me occupied at the time, and I forgot you were even supposed to be out!
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Andy.
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