Finally finished m20 rebuild,mot and test run the other day,no bits dropped off and covered a steady 35mile,called at a friends for the first stop[he has a van!]and got chatting so it was getting dark as i got home, surprised as i put the bike away that a dull glow was coming from the new exhaust pipe[marked m20 on carboard wrapping] at the exhaust outlet,i have had the pipe a few years so do not know who the manufacter was, also i had a lovely cambells silencer that fitted straight on but was not new, this does keep it quiet.never had a sidvalve but they all say they run hot?is this normal.checked the timing today and its still spot on,i had fitted forum members solid copper head gasket and today noticed a small wispering at head joint near head steady bolt so head off later and anneal new gasket that i perhaps should have done in the first place.[head and barrel checked on surface palte before fitting]do the exhausts glow in the dark?thin pipe?i dont think valve timing is out, dot and mark on the cams seem straightforward but did not check with degree disc,any ideas? thanks arthur

Hi,Arthur If you have checked ign/valve timing and its spot on the next place I would look is spark plug colour, could be a weak mixture indicated by a white coloured electrode, Dave.

thanks, i will check tomorrow, never thought of week mix,needs sorting before damage, thanks again.

Arthur, I've had the same issue with my M20, and with my BMW Boxer. In both instances, I couldn't find anything wrong, and the problem just went away. It made me wonder if the fuel had something to do with it. I can't imagine how that would work, but mechanical problems don't usually fix themselves. I wasn't using additives, incidentally, and can't remember whose petrol I was buying. But as I said, the problem resolved itself. Perhaps a fuel with a higher ethanol content (or whatever) is the gremlin.

email (option): dannydefazio@sumpmagazine.com

If your head gasket is 'whispering' you may well be drawing in air there and causing a weak mixture. It is always best to anneal the gaskets before fitting. Heat (carefully) to red and quench immediately in cold water..Ian

email (option): ian@wright52.plus.com

I like the air entering the cylinder from a head gasket leak. It also can explain Danny's self-healing problem. If carbon build up seals the leak, it might appear to have 'healed.' Perhaps a retorque is in order?

Kevin

thanks to all for help and advice,will update when i get the head gasket sorted,arthur.

Hey Arthur, my M20 was quite well known for glowing at night, I put it down to valve bounce at high(ish) speeds.I fitted some inner valve springs from a W/NG and hey presto, no more glowing, and slightly higher revs. This was 20 years ago now, no adverse wear despite the higher loading.
Cheers, Mick.

email (option): mick@motorbikemike.org.uk

email (option): teladelujo@msn.com

thanks again all,checking this weekend.