homda 250f in a yfz 450 frame.

[hanzito]

I am looking to put a 250f motor in my extra 04 yfz 450 frame the only major parts I don't have is the rear swinger and rear brake. Is there any thing I should be careful of or looking for.

[dehner47]

dont meen to high jack your thread but whats the deal with guys or girls putting in a 250f motor into a bike bike frame.cause a 250f is equal 2 a 125cc 2stroke,wouldn't that motor be way under power since its gotta move the weight of a large biike? or are/can you run the bike in a smaller class? just something i been wondering since i've seen a few people do this combo in the past.

[ss440ex]

Out of the two,


I would think that the 4 stroke would have more over the 2 stroke.

[dehner47]

i agree.the 250f should kill the 125cc bike in the powder department.but isn't the 250f gonna be under powdered in order to pull around that large chassis and rider?? or is it used for a smaller class like the blaster class or age classes??

[C41Xracer]

ya its ran in a smaller displacement class

[dehner47]

ok.i understand now.wasn't sure what class that motor was good for.i just knew it would of been way under power for the 450 or open class.how does that motor work in the biker framed bikes?? does it make good rear wheel power? good enough to justify the time and $$$ it cost to build one??

[stauffracing#4]

to clarify the youth class you can run up to 300 cc at our track.and we have a couple of blasters with this motor in them and let me tell you they rip but alot of mod work to make it fit.with the yfz it will be alot cheaper now and later when he is ready for a 450.yeah he only weighs 88 lbs.

[stauffracing#4]

sorry guys had the same question a little farther down .

[hanzito]

i will eventually put my son on this set uphe is 10 now. in the mean time my girlfriend will ride it she is 5 foot and 100 pounds. so it will work ok. and you can get upwards of 30 horse out of these motors so close to a stock 450 and half the motor. I am doint it because this way my son wont out grow the chassis as opposed to a 300ex frame. and i parted out one of my 450s so i am going to use the left over parts. the only thing i dont have is a rear swing arm and brake. I also have a 250f motor in a shifter cart already so i can get it rolling for a few hundred bucks. not bad. at first my son will race it at flat track in the 300ex/blaster class. then move to motocross when i think he is ready. right now he rides a heavily modified xtreme typhoon with a manual clutch motor. I would have prefered the 250x motor for electrice start bu ti have the 250f motor now and it makes more power.

[hanzito]

well i checked the garage and looks like the only parts i need are the rear swing arm and brake caliper and the rear fenders. so it looks like the project is moving into the planning and info gathering stage. to try to identify possible issues.