All stock heads are not equal

[Larry Trotter]

Just a little heads up if you are having head gasket problems. My 66/80CC China girl had a head design that only allowed about 1/32nd of an inch to seal on the gasket. Note in the pictures that the ring that seals against the gasket is much narrower on one head than on the other. Look carefully at the head gasket picture and you can see it jus barely catches the edge of the gasket. Also there is a much larger combustion chamber which will make for a lower compression ratio. Only noticed when I was turning the head around to check fit for my 20 inch build.

 

[Tyler6357]

Some of those stock heads are just not made to spec. Also, I've seen stock heads warp from heat because they are so thin and the steel is such low quality.

 

[Larry Trotter]

When I get some time I think I will build a little fixture to hold a head so I can turn it in a lathe. Then I can clean up the surface and get it absolutely flat.

 

[curtisfox]

Wet and dry sand paper on a piece of glass or a machined surface, would do the same............Curt

 

[Larry Trotter]

It would be best to turn it down to move the sealing ring in to make it wider to seal on the gasket. Then turn back the head including the bolt holes to let it get a good seal. Problem with this one is the ring that contacts the gasket is too thin.

 

[JerryAssburger]

It IS amazing the variety and variation of the stock replacement heads that you can order for the same engine. I went from a Squish-Head (which came with the motor but leaked) to a Dome-Head by accident, and ended up with a decent running engine. I'm thinking for success to just hoard everything into boxes and drawers, and eventually you'll have a combo that works...?