What motor

[jman71890]

Well I have 3grand to spend on something, and I want to put a different motor into my 300ex. I dont want to hear people telling me to just buy a 450, I dont want to spend that kind of money and I think it would be a fun project. I was thinking either a 85 motor or a 125. Would a 85 motor be more powerful then the 300? I know it would hit harder. Also about the motor mounts, thats really the only thing I would have to do, that and the radiator mounting. Also what gearing are people running with an 85 motor or a 125 in a quad. Thanks

[Ripitupfilms]

just save your money or build up the 300ex

[bansheemorphine]

i'd suggest buy a bigger quad but you said you don't want that an 85 motor i don't think would have much more power then your 300 and i am not sure about the 125 i'd suggest a 4 stroke motor possibly a 400ex motor but if you have your heart set on 2 stroke i'd go with a 250 should be an easy build just have to make motor mounts and rad mounts then probably a different intake

The 85 motor is sosposed to feel like a blaster but you have to rev it more.

I would get a yz400 motor. You can pick them up for $800. A 300ex has a big air cooled 4 stroke motor in it so it will fit almost any motor in it. B4 the 400ex was made some one took a 300ex and threw a xr400 motor in it and thats how honda came up with the idea of the 400ex.


But if you have $3000 to spend you could just sell the ex for around $1000 and have $4000 total and pick up a used 450 or even a race ready 400ex for that price.

for 2 stroke i would get a 250cc or a cr500 motor

[brian250racer]

Put in a Cr250f or the Yz250f motor...

[stocktires]

350X motor and build up the suspension. Its a much faster motor, yet wont overpower the 300ex chassis. Also its been done many times before so you can get info from others.

[KingpinsEx]

Originally posted by stocktires
350X motor and build up the suspension. Its a much faster motor, yet wont overpower the 300ex chassis. Also its been done many times before so you can get info from others.

I agree those motors rip, not far off from a 400ex powerwise. And you should be able to find one fairly cheap...although they are somewhat rare. That would be your best bet for a motor for a 300, should fit right in and have large power gains...

[zorg]

What is your age? I would not go with the 125cc motor the motor of choice is cr80. And yes they are fast and fun,and it would be faster than a blaster ,300ex if built right. cr80 motor stock is about 18hp. You have to be on the pipe alot with this motor no bottom end. I have one and it was a fun project more than just motor mounts and radiator. You'll need a new rear sprocket for a 428 chain,mod the pipe to fit,clutch cable,mod the kick starter. Use the swingarm bolt through the motor. Some people just move the motor forward and weld mounts not a good choice. There is alot of little things to do nothing major.