ok here it goes. just got a rolling chassis together and now need a little help on the motor. i got the bottom end together tranny and all. i'm running a +4 crank. now my question is what should i run for a top end???most of my riding is just dukein in a field or a short ride.i want something with some power but also wont be afraid do go on a short ride...any info will help...

 

hmmmm...I know the 300ex and 250x have the same bore if they are stock you could go with the 330 bigborekit but its pricey .I would juist get the topend honned and go up a size on the piston and rings ...Ive heard of someone having the 300 sleve pressed out of the cylinder the having it bored to fit a 400ex sleve I want to try this one later on my 250x motor (incase you dintend know the 250x cylinder is compatable with the 300ex cylinder...the diffrence is the crank and connecting rod)and if you go big add a oilcooler

 

i dont know how this will help. i have a 87 trx 250r.

 

well, you said you had a basket case, I would put together what you have for now, I would use the head and cylinder you have, I would have it bored and new piston and rings though. that way you can see how u like it and it will keep the cost down. also doing it this way would be good to get it running first, check to see if you have any problems with the rest of the atv and make any mods later.

 

lol my bad .......srry