Atc250r 4 stroke swap

[RIDE-RED 250r]

I think a 250r as a 4 stroke would be like a crotch rocket as a V-twin or a corvette with a diesel motor.... its like........ "but why"? Especially with all the modifications that would have to be done. Its not worth it to me. I agree with everyone saying that you probably want a 350x. If you did have an R, I would leave the 250r as is and change the sprockets for more torque if you want it to be better in the woods. Add a few teeth to the rear sprocket or drop 2 teeth on the front sprocket. You won't be crying about torque or no low end power anymore. You'll be looking for lead to keep the front wheel down Lol.

Or increase displacement significantly...

[YamaBoss]

I think you guys are missing his idea here. He wants nice mild motor machine. Something like a big red with the suspension of a 250r. The last thing he wants is a 350, 400, or 600 motor.

[fordnut79@hotma]

Exactly Yamaboss.

[atc007]

Everyone is different.. You can see the west coast guys,liking a 200x or 650. Where us woods guys want almost exactly the opposite. It all depends on where you ride,what you ride. We're ALL different. Hence, Kawasaki actually sold Tecates, Yamaha actually sold Tri 'Z's. After the 250R had been dominating off road racing for years. We're all different. If you want a 4 poke R, I say make it happen!

[Jmoozy27]

I still say it sounds like a super x. Performance meets comfort and simplicity. Not a very hard build once you find the motor. A lot of options once you do.

[Bilster]

I've floated around the exact same idea. My 250R was a handful in tight, soft tracks. My 200X was so much smoother. I didn't work nearly as hard to go fast. I have a 86 200X frame and when I inquire on how to make it the ultimate handler, it basically ends up being a 250R chassis. Why not just start there? Keep us posted. I will eventually try it myself but I'm up to my elbows with my 86 200X motor into a 1991 CR125 chassis.

[RubberSalt]

I'd look into increasing compression, add a reed spacer, and clean the ports up. Don't raise them, just clean them up. In same cases, epoxy them. in.

Your port size is going to be relative to your target RPM range, displacement, and compression. More compression requires bigger ports. By raising compression, you are technically lowering the rpm that achieves peak hp... By raising compression, you are adding power all around.

Now if you have no motor and are looking for a 4 stroke, then there are tons of options. I'd recommend a CB350 engine. Light weight, reliable, and plenty of power. And yes, I'm talking about the old stuff. http://en.wikipedia.org/wiki/Honda_CB350