Re: '81 CB750F trying to get it road ready.

Posted by seestheday on
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/81-CB750F-trying-to-get-it-road-ready-tp4042282p4045172.html

Why do you think it's a blown head gasket?  Because of the smoke?

That only applies to liquid cooled engines.  White smoke from a car often means coolant/antifreeze is getting into the combustion chamber via a blown head gasket.  This can't happen with your bike because you don't have any coolant/antifreeze.

White smoke for these engines usually means that you're getting oil into the combustion chamber somehow.  The usual culprit is a bad valve stem seal, or rings that have gone bad.

You say that you checked your spark plugs.  Were any of them oily?  Also, you say that you saw white smoke leaking out around the #4 cylinder.  Was it right where the exhaust header meets the head?  That could just be a bad exhaust seal (e.g. the shop may have installed your header collars backwards or something simple like that).