I got one of Jim's heads from Pirate and it worked on my black slant 80(66cc) that I got from Lucky Early Bird ...So I tried it on my first 80(66cc) that I got from gasbike that had the 6mm cylinder studs. I put dowl pins in the head to take up the slop from the smaller studs. And I had to ream out the head gasket to get it to fit the billet head properly. This was my first engine and it has been gone through with all the proper mods. It screams better than any other engine that I have had so far. So my advice would be to get the head while you can. Make sure the big open area of the head gasket fits over the lip on the billet head. I've used regular slant heads and they warp...Jim's product's are #1Jims billet heads won't work properly on all engines! (All engines are a little different)
If you read the threads on them, Jim talks about what your engine must have for the new head to work properly.
Jim's products are the best, but you must do a little research to be sure they will work for your application & give you better performance!![]()