what type of bore

[nicktrx400ex]

if i want to race but want a reliable motor and want to se 93 octane what bore should i use. for a 400ex


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400ex
K&N filter & pre charger
jet kit
holeshot xcr front and back
biggun rev box
nerf bars

Go to heaven when you die till then ride like HELL!

[2muchquad]

416 is the most popular around here,seems to be pretty reliable as well.

[Quad Dude]

you dont have to bore it, personally i like the stock bore high compression with a good cam and pipe. and its a whole new bike. and i have seen a lot of the 440 run and i wasnt to awful impressed. but then some times the run great. but if your stuck on a big bore 426 is the way to go.

[wilkin250r]

Originally posted by nicktrx400ex
if i want to race but want a reliable motor and want to se 93 octane what bore should i use. for a 400ex

You can run 93 octane on just about any bore you want. It's easy enough to build anything from stock to 500cc that will run on 93. You are confusing bore with compression.