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Urgent !

Sorry for the over the top header, but am about to fit a new piston to my triumph 3hw, which is oversized by 60 thou , my old piston had a flat top to it, and the replacement one I have has a domed top, has any one fitted a domed top piston to a 3hw????
Many thanks

Re: Urgent !

The flat top piston is probably the original one fitted at the factory when new and is low compression ratio, the domed one could be off a 3H 6.7:1 or Tiger 80 7.5 :1 compression ratio, I've got a few 3HW engines and some of them have domed pistons, and some with the original flat top.

Re: Urgent !

I read once in a magazine article that after the war the grass trackers used army surplus 3HWs and fitted the Tiger 80 piston for more power.

Re: Urgent !

Thanks Steve for the advise, guess I’ll fine it a go just hope it clears everything valves etc
Piston is new and made by hepolite!

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