400ex-250r hybrid

[blasterandy]

Has it been done and how. 400ex everything with a 250r engine in it.:confused:

[Barrymaxx]

It can be done. Considering the the 25o motor is small compared to the 400, there should be plenty of room for a radiator.

Service honda sells a kit to convert your 400 to a 250r hybrid. Then sell off your frame, motor, carb, electrical, exhaust to make back some money.

[Flyin-Low]

Yep, I've never really ridden a 2-stroke before and I was kind of interested in this instead of just selling my 400ex... here's the link http://www.servicehonda.com/service.html

-Martin

[blasterandy]

Yea i saw that but its a whole helluva lot for that kit. I would rather buy the 250r engine, carb, electrics and tranny. Cause i could prolly regain all the money for it by sellin the engine, bottom end and likewise.
What all would i need to convert it.

[GPracer2500]

FYI, the SH quad uses a CR250R engine, not a 250r engine.

[JOEX]

Originally posted by GPracer2500
FYI, the SH quad uses a CR250R engine, not a 250r engine.
Are there any noticable differences in the parts and performance?

[blasterandy]

i thought of a nother potentail problem being a exhaust that would fit. I kind thought that the service honda pipe might me a good alternative to buying a 250r pipe.

[GPracer2500]

Originally posted by JOEX
Are there any noticable differences in the parts and performance?

Both. The CR engine has a flapper style exhaust valve and sub-exhaust valves. They work together to alter exhaust port timing and expansion chamber volume. The effect is kind of like having a bottom end port job and a bottom end pipe that switches to a top end port job and top end pipe at a certain RPM. The only downside of haveing this system is slightly more maintenance (but it's minuscule in light of the performance advantage).

SH uses the 92-01 generation of CR engine. Many regard it as the best 250cc two stroke engine Honda has ever made. I have one of these engines in a 95' CR250R and can vouch for it's all-around goodness. I love it. Some will say the 2001 CR250R is the best 250 dirt bike Honda ever produced--second generation aluminum frame and their "best" engine. After 01' Honda went to case reed induction and a solenoid activated PV. Many felt this was a step backwards. In theory it should be better but in practice, somehow it's not.

The one thing the 250r engine has that the CR engine does not is a counterbalancer (to help with secondary engine vibrations). The CR500R engine doesn't either and it's comparitively heavy piston and crank add up to viscous, frame breaking vibration in a quad chassis (so I'm told--I've never ridden a CR500R engine'd quad). I think the lighter piston and crank in the CR250R engine must allow it to get buy in a quad frame without breaking stuff. In a dirt bike chassis, engine vibrations aren't too much of an issue.