Hey, I am buying a 250r and I am wanting to buy a big bore jug for it, I Don't want to stroke it as I want to keep reliability. I know a 310 is a bolt on none stroked motor, but what about the 330, 350, and 370?? I am really interested in knowing as I need more power, I've ridden a 250 that was drag ported on 50/50 pump/race gas and It was powerful but I want more bottom end than that. Im 5'7 300lbs, whats the best for me? thanks a lot.

 

You can get the 310 and the 330 in bolt on fashion. You can get a 330 and a 350 that doesnt require stroking, but the cases must be machined to accept the larger sleeve. The bolt on 330 only gives one bore size to work with. The 370 and 380 is a stroked crank with the 350 cylinder. The 350 cylinder is designed differently than the smaller 310 and 330's. Stroking will always increase torque output and make for a more grunty type motor. The thing about the 370 TRX motor is that they still make the power on the top end as well.

 

Be careful on what you do the 350 /370 will not rev like the 310/330. what type of ridin are you gonna do?

 

your a bigger buy, so if I were you I would go with the 350 kit.

 

So I can go with the 350cc motor by ESR with a powervalve without a stroked crank?? That sounds like what I want to do.. I do trail riding, playing around, some hills.. but no drag racing. I've riddin a high sky revving 310 before and it was ok but i wanted more torque.

 

Yes you cna get it from ESR (non stroked) But just to let everybody know that torque is just as important as HP when you drag race.

 

stroking doesnt decrease reliability like you think, nor will a 310 outrev a 370 by a considerable difference. My 370 makes power until 10,500rpm

Id much rather have a smaller bore (350) longer stroke motor then a huge bore stock stroke. The more weight you fling up and down puts more stress on parts.

Your size you should at least go with a 350, the 370 would suit you better AND is reliable. I have 3 of them, in case any of you guys care. Also have a 310 and a 330