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[Isettaman]

Hi. I'm in the process of sorting the head on my 1951 350cc bullet and have found that the vent from the decompressor shaft to the exhaust port appears to be blocked. I am struggling to find exactly where in the exhaust port it should come out as prodding the vent from the decompressor end produces firm resistance. Any helpful suggestions gratefully received.
Thanks Dave

[Mark M]

I had the same problem on my 1955 Bullet (the Ebay 350). The vent is actually just above the exhaust valve seat, when cleaned it looks like a tiny half moon, one edge being the steel of the seat and the other the alloy of the head. It gets choked with oil coke which solidifies to near rock hard so you'll need to work it with a drill bit, I put a suitable sized bit into a tap wrench and worked it by hand. You might need a pick (dentist's tool not a roadmender's!) to clear the combustion chamber end due to it's small size.

REgards, Mark

[Paul M H]

If this works you should be able too just see it on the bottom picture just above the right had side valve seat.

[Isettaman]

Thanks Paul & Mark

I've got it sorted. I just needed that little bit of encouragement as my initial thought was that it had been sealed off. A bit of scrubbing with a toothbrush soaked in petrol and the digging with a strong scribe and, hey presto, I now have a clear vent. I wondered why I got a cloud of white smoke out of the top of the decompressor previously. Smoke being cured by new valves, guides and piston rings. Thanks again.
Dave

[papasmurf]

Paul M H, the inlet and exhaust ports look as if they could benefit from a polish, or is it too late?

[Paul M H]

Its not my head just a picture of a second hand one that's for sale on Hitchcocks web site I used to illustrate better.