250ES...300 Top End, or full motor?

[MudBug]

one of my big reds is really tired, and im sick of getting beat by my father on "his" big red. So I was wondering. would it be better to get a 300 fourtrax top end and piston, etc. or to get the full engine from the 300? how would the 300 top end work with the big reds gearing? I think I would have trouble getting a full 300 engine. but you never know. I need you guys' opinions.

[atc500x]

The top is the same,250 and 300 use the same piston,same bore.The difference is the stroke,so you have to change the complete motor.

[MudBug]

oh I thought the 300 had bigger bore and bigger piston. so the higher displacement comes from the stroke. crap. I knew the topend swap would have been too easy:lol:

[harryredtrike]

looks like a motor swap,do the mounts match?

[MudBug]

so ive heard

[mike84bigred]

Yes they do. You will have to change the side shaft on the motor, or else it will not line up with the housing on your ES. Also have to bend an oil line in the motor or something. We have been down this road before, and there is guys here that have done it. Search it, and you should find what your looking for. Good luck

[MudBug]

I think im going to just overhaul the engine I have now. now that I have had my project ES all stripped apart, I can do it on my others ones now. from experience :naughty:

[mike84bigred]

Good idea:p :p :p :p