I have never tried to polish the inside of the combustion chamber on these, they're not that bad, though the iron barrel Bullet's combustion chambers were always machined, which makes them look a little rougher by comparison. As far as I know only Ace has used ceramic coating on the inside of these heads, but AFTER the combustion chamber has been built up with weld and re-worked. I have however smoothed off the edges of the combustion chamber as well as the decompressor hole.
There are some areas where these heads can use a bit of work.
1. Inlet port. I posted a picture of the stock port recently, what's with the oval-ish port shape, 32 x 36mm, roughly? The stock carb on these was only a CV29. Dell'Orto make a carb with an oval port, maybe I should have bought one of those for it. Anyhow, it makes opening up for a larger carb easy.
2. Exhuast port. These are terrible on a stock head, a very small hole, and rough barely describes the finish. With the narrow inner bore lean-burn exhaust pipe it probably wasn't worth the factory's time to finish them properly, that was left to us!
3. Valve seats. For some reason the outside edges stick out into the combustion chamber by about 1mm, on this head I had them cut back some years ago so that the outer edges are flush with the combustion chamber surface. Also they're not smoothly blended into their respective ports, with the inlet valve seat in particular actually sticks out into the inlet tract slightly.
I gather that the Ace Fireball conversion for the AVL head deals with all of those issues.
That said, Bullet Whisperer managed to get a tuned Electra-X to do 103 mph with a totally stock head, this was left unchanged at the customer's request. So as imperfect as they are, you can still put together a decent engine with one.
Today I got the alloy tube to finish off the carb mount.
There is a teeny hole drilled in the carb as part of the idle circuit, but you can see where the end of the mounting stub could obstruct it.
Just needs a groove filed in the end of the stub.
A.