Ok, I'm going to build one, but... I have a 02 cr250 also.. Same concept.. What do you guys think and what class could it be raced in?
I considered the super single route, especially since I already had a CRF450X in supermoto trim. Though I went another direction after pricing out the parts I wanted. Ended up putting the 450X motor into an RS125 frame. Depending on how cheap you can source your parts, this might be a financially viable option. RS125's are getting real cheap. For me it was cheaper to do the hybrid than it was to build the super single.
You would need to do some serious tranny work to get a 250 MX bike to keep up with a 450 on a road race course.
Yup, getting out in front of the 450s on my RM85 was possible. Staying out front was sometimes the challenge.
How tall/heavy are you? I've considered this, but I'm a big boy (6'4''), I don't think I'd do well on a 125 frame. What is the physical size of the RS125 hybrid compared to a converted 450?
Forget it. I'm 6'3" and can't even bend mt knees enough to put my feet on the pegs of an RS 125. I would have loved to try one of those little buggers...
Still clubman legal. It's been tried. I tried to buy an unfinished Chuck Dees CR500 in a TZ250 frame project a few years ago until he changed his mind. I think without some kind of counter balance it would vibrate right out of the frame. Go for it! :up:
I'd consider a TZ125, I believe they're "roomier" than the RS. I'm 6' and was able to ride my son's RS...just BARELY. But man, best bike I have ever ridden!!!! Telepathic handling!!!!! With that said, I would ask the question over on the USGPRU board. I know someone makes a "big boy" kit for the RS.
Maybe a stupid question, but how do you get "random motor A" to fit into "random frame B" when motor mounts, counter sprocket locations, etc don't mate up at all? I'm assuming you'd have to have some fabrication skill to make your own tabs/mounts?
Me 5'8" - 153lbs - long walks on the beach, yada yada yada. Yes they make a big boy seat, widebody fairing and extended rearsets for the RS. There are definitely bigger dudes on RS's doing just fine. The big boy parts are supposed to help a ton. I fit just fine on my stock RS. Takes some getting used to by the riding position can really affect the handling. The handling genuinely is telepathic but with the power of a 450. I haven't touched my RS125 since this got built. Physically the 450 super single dwarfs the hybrid. But that's the point. The reason it handles so well is the geometry, size, and weight.
So if you choose a CRF motor, fitting it to a TZ may be a tad more difficult. Random motor A into random frame B isn't all that random. It lines up pretty danged well. Both motors are mounted to the swingarm. The CRF swingarm pivot bolt is a few mm smaller than the RS. I had the bearing bushings machined down a tad. Spacers will allow you to line up the sprockets easily. As for motor mounting...there's at least two ways that I've seen done successfully. The CRF motor size wise is probably the tightest fit. Any further forward (though you can't if you use the swingarm mount) and you hit the radiator. Height is the biggest issue. Had to bash out the bottom of my tank to make it fit. Then I still had to raise it a few mm.
