??? about high comp pistons

[jsmith2232]

What is the stock 400's compression?
How high can i go w/o stretching head bolts?
Where do i need to start running high octane fuel?
With a stage II hotcam what would be the best make and comp piston i could get( i do about 70% trail and 30% dune riding)

[DAVE14]

The stock ex comp. ratio is 9.1 to 1 Ive heard of people gettin away with as much as 11 to 1 with stock studs ,but I wouldnt recomend it I run 12.5 to 1 with gt thunder studs & no problems Ive seen cyl.s threads on th ex tore right out from not using the heavier studs I dont know if stretching occured but the gasket obviously popped & a mess in the cyl. (do what you want but its money well spent )& while youre in there get a 02 crf 450 timing chain , why not a cam also & youll really wake that thing up !