kx125-kdx project questions?

I was thinking about putting together one of those nifty kx125/kdx2?0 hybrid bikes but was looking for a bit of advice first. I want to create a great back up trail and woods bike. My back up bike right now is a yz250, and aside from it being kind of a lemon, it is just too much whenever it actually does feel like running nicely for me. I love the feeling of 125's and always have, but having a smoother motor with a bit more bottom end would make the bike a lot less tiring to ride. I have read a few of the kx125/kdx220 conversion threads, and there seems to be a few compatibility issues among certain years. What year kx125 is most compatible with what year kdx200/220? Also, should I be looking for a kdx200 or 220 donor bike? What differences are there in the motors? I would like to do this in as cheaply as possible. The other thing that I have to consider is green/red sticker status here in CA. Would an 00-02 kx125 handle a lot worse than a newer one? Any advice would be greatly appreciated. Thanks guys.

I was thinking about putting together one of those nifty kx125/kdx2?0 hybrid bikes but was looking for a bit of advice first. I want to create a great back up trail and woods bike. My back up bike right now is a yz250, and aside from it being kind of a lemon, it is just too much whenever it actually does feel like running nicely for me. I love the feeling of 125's and always have, but having a smoother motor with a bit more bottom end would make the bike a lot less tiring to ride. I have read a few of the kx125/kdx220 conversion threads, and there seems to be a few compatibility issues among certain years. What year kx125 is most compatible with what year kdx200/220? Also, should I be looking for a kdx200 or 220 donor bike? What differences are there in the motors? I would like to do this in as cheaply as possible. The other thing that I have to consider is green/red sticker status here in CA. Would an 00-02 kx125 handle a lot worse than a newer one? Any advice would be greatly appreciated. Thanks guys.

any kdx motor from 95 to present, they are all the same. the 200's and the 220's are identical motors except the cylinder/piston , the head, and the carb. they are the same physical size and you can swap top ends between them. any kx125 after 99 works, the 03 and later are harder to do, but people seem to like that frame more for its handling characteristics. as far as stickers go, i think youre screwed no matter what year the bike is. there is a lot more info on the 99-02 bikes as well. you may not need a whole kdx either, just the motor and a few odds and ends, almost everything is used from the kx

Thanks for the info Sean. What do the performance differences between to 200 and 220 motor seem to be? I'm guessing that if they have the same piston and top end that the 200 has a shorter stroke and is therefore a bit of a quicker revving motor? Just a guess.

The 220 is a larger bore (198cc vs. 216cc, I believe). It also came with a 33mm carb and a low-mid porting aspect instead of the KDX200 35mm carb and better high RPM delivery powerband.

any kdx motor from 95 to present, they are all the same. the 200's and the 220's are identical motors except the cylinder/piston , the head, and the carb. they are the same physical size and you can swap top ends between them. any kx125 after 99 works, the 03 and later are harder to do, but people seem to like that frame more for its handling characteristics. as far as stickers go, i think youre screwed no matter what year the bike is. there is a lot more info on the 99-02 bikes as well. you may not need a whole kdx either, just the motor and a few odds and ends, almost everything is used from the kx

We picked up a 1993 KDX200 a couple of weeks ago and will be trading my CR250 for a 2004 KX125 and $$. Will we run into a lot more problems? I'll try to research more threads to see what I can find. You mentioned a 95 to present motor---why?? My husband might keep my current KDX200 for himself and might seek another donor KDX200 but it's a 94.

The 95 and up motor seems to be the better choice of the two, but can't offer much imput on it I have a 05 kdx 220 in mine and the choice on the frame is 03 and newer due to the fact its the same all the way through as far as plastics and odds and ends, the chassis was better, and a little smaller, turned way better than previous years, the tank will bolt on with no mods, and the pipe will fit with no mods. you will have to build your own mounts and rely on rear headstay only, cutting off front headstay, but the change over to mix the two is not hard just time consuming. and a little attention to detail is a must

the idea behind the hybrid is to have a torqey 2T in an mx chassis. the 95 and later motor are the ones that fit the bill. the 94 and pre were diff. i think they were more mx like, but having never seen one or ridden one im not sure. plus there is a lot more performance stuff made for the 95+, not so much for everyhting before that. the piston is different on the 220, and the porting is different. and some of the parts other than the motor that are needed from the kdx may be different on a 93. i would suggest holding out for a 95+ unless someone else corrrects me as im still ignorant on the older generations.

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