33 replies to this topic

[minimans]

Replace all four valves! and check the seats carefully. good enough won't be! If it is not sealing perfectly it will just promote another burnt valve. Tappet gap is also critical to prevent a re-occurrence. 

[russo]

I like to know exactly what the problem is before I start dismantling the engine. This can be done by carrying out a leak down test. Remove all spark plugs and bring each cylinder one by one on to firing stroke (TDC) By screwing in a compressed air coupling into the spark plug hole then pumping up with compressed air you will very quickly find where the air is escaping. If you can hear air escaping out the tappet cover breather its rings, if it comes out the exhaust its an exhaust valve, if it comes out carburettor intake its inlet valve, if bubbles appear in cooling system then its head gasket and if it comes out of next door spark plug hole it gasket blown between cylinders. This way you will know exactly what it is before you remove head.

Edited by russo, 26 March 2017 - 11:18 PM.

[Magneto]

I agree with Minimans, replace all the exhaust valves, I use the stellite faced valves. I would not mess around with lapping, just take it to a shop and have a good 3 angle job done, then reinstall.

[Chris.Williams]

I agree with Minimans, replace all the exhaust valves, I use the stellite faced valves. I would not mess around with lapping, just take it to a shop and have a good 3 angle job done, then reinstall.

I agree, mine went to the shop, bloody magic job done for very few gold pieces.