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[Stevefromleicester]

Any ideas ?
My 1957 Model g 350cc starts first kick,runs OK NO smoke from exhaust but when it warms up I start to get some smoke looks like it is coming out between the head and barrel but fitted new copper gasket (Circular type) and new pushrod oil seals.
I see there is a different cylinder head gasket for the bullet that goes around the pushrod tubes would that fit ?

I am hoping after a few months rebuilding to take it to a VMCC trial in Uppingham this weekend so any advice appreciated.
Could a clogged breather cause this ?
Nothing appears to come out of the breather that discharges onto the primary chain.
Could the cast iron block or head have become porous ?
Thanks
steve

[Mark M]

Cast iron heads or barrels are unlikely to warp or be porous but they may be scored from previous Owners' clumsy rebuilds! It won't be the breather being clogged, oil would come out elsewhere, for instance the magneto drive from the timing chest. The answer is almost certainly to use a bit of silicon sealant round the pushrod tube holes and also round the spigot on top of the barrel when rebuilding. It "cooks" into place and really works. Also make sure you have properly annealed the copper head gasket before fitting! REgards, Mark

[Stevefromleicester]

Ok I will try some silicone sealant.
Thanks for that.
I used a new copper gasket how do I anneal it ?
It runs great it's just the haze that appears when
It warms up. I did think the new pushrod seals
Might need a bit of backup.
The compression also seems ok .
It won't take long to get the head off again to try this.

[Mark M]

To anneal (which means re-soften after the work hardening of being clamped under pressure,) a copper gasket put it on the gas ring (or electric, that's what I have, an old cooker in the garage,) until the whole thing glows cherry red, then using pliers (obviously !) drop it straight into cold water. A film of black scale will appear as it cools, wipe this off and it's ready to use. Make sure any holes (stud holes say,) do not have raised edges by gently tapping them flat with a hammer on a flat surface. Some folk will argue a slightly different process but the principle is the same. REgards, Mark

[Stevefromleicester]

Right better get on with that now before my wife gets
Home as my cooker is in kitchen.
Cheers
Steve

[PeteF]

With copper, it matters not whether you quench or not, unlike steel where it matters a lot!

[Stevefromleicester]

Heated circular head gasket up for Model G on gas cooker to dull red heat then plunged it into the sink where all the black scale as if by magic floated away leaving a bright coloured and softer head gasket.
(NB This can be hazardous but its even more hazardous should your wife return home partway through asking about the black scum ring in the sink).
Refitted with loads of high temp silicone around the pushrod holes and the rest of the head cylinder mating surfaces lets hope that does the trick.
Took less than an hour to strip bike down ,remove gasket, anneal it, and refit everything.

[Mark M]

Nice one Steve, let us know how it goes!
REgards, Mark

[Roy]

Hi Steve. Perhaps you should check your exhaust/silencer for excessive back pressure due to heavy carbon or a baffle plate that has shifted which is what happened to my 1945 model causing overheating and smoke vapour all over the place.