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Chin_Chilla
10-16-2006, 06:51 PM
My friend just bought a 2003 400EX, just 1 year newer than mine. Well we are out riding and he was riding beside me and he decided he wanted to floor it and try to throw roost on me. Too bad I have a 440 and punched it and left his arse! Anyway he says it has a 440 kit on his also, but there is no way i smoked him he even got the head start on me. I think it is stock motor wise but he does has KandN and white bros. complete pipe, jets, etc. Anyway for the question, how do you tell if a motor is bored out, because I want to know if his 400EX is really bored or if he is talkin out of his *****. I really dont want to have to take his motor apart, so any ideas? Sorry for the long *** post.
400eXr1d3rZ
10-16-2006, 07:19 PM
Dyno.
2004exrider
10-16-2006, 07:25 PM
You can always get a compression tester. If his has a different piston in it, it's more than likely going to have higher compression than stock which is around 120psi.

Jimmy
zrpilot
10-16-2006, 07:52 PM
Originally posted by 2004exrider
You can always get a compression tester. If his has a different piston in it, it's more than likely going to have higher compression than stock which is around 120psi.

Jimmy

Compression ratio and cylinder pressure are not neccesarily related.......
10-16-2006, 08:21 PM
Run it on 87 octane gas and see if runs like chit;)
I heard about that, so I never tried it...
Joe250x
10-16-2006, 08:37 PM
it's easy, take out the sparkplug. position the piston at bottom dead center. measure some oil, about 500 cc's worth. put it down the sparkplug hole until the cylender is full and see how much is left. then subtract that from how much oil you started with. that will give you a rough estimate. getting the oil out can be harder though.
NY06400EX
10-16-2006, 09:19 PM
^^^This method would work but good luck getting the oil out - lol.
Chin_Chilla
10-16-2006, 09:20 PM
Lol those all seem like good ways, but I can't exactly go to his house, jack his bike for a couple of hours, and test and all that. So basically there is no way of telling by just looking at the motor, listening to how it sounds, etc, etc? Thanks for all the ideas guys!
400eXr1d3rZ
10-16-2006, 09:22 PM
Originally posted by NY06400EX
^^^This method would work but good luck getting the oil out - lol.

Burn it out.
NY06400EX
10-16-2006, 09:55 PM
Would you recommend that to everyone? Even a "novice" or beginner DIY'er? I think that could lead to more harm than good, just my .02 cents.