Ok so this isnt the first hybrid KTM RFS motor in a 250-450/505 SXF frame(seel links below) and likely will not be the last, but I felt like posting it anyway. my 2nd hybrid *may* be the first to use a 250sxf frame other hybrid build threads http://www.ktmtalk.com/showthread.php?t=375749 http://www.advrider.com/forums/showthread.php?t=620478 http://www.ktmtalk.com/showthread.php?t=408919 http://www.dirttricks.com/rfs_in_new_frame.htm ride test http://www.enduro360.com/2010/09/27/featured/the-dirt-tricks-ktm-rfs-hybrid/ This was the first thing I noticed, once I cut the lower engine mounts of the frame (to sit the engine inside.) There was much less plumming clearance than I expected. <!--?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /--><o></o> <o></o> <o></o> dirt tricks got around this by machining a 90 degree adaptor for the t connector (as can be seen below)<o></o> <o></o> <o></o> <o></o> The main issue with using the full height RFS motors (450 exc/mxc, 520/525) is the exhaust clearance around the yoke area. I chose to cut and weld in sections of a sacrificial 250sxf engine cradle.<o></o> <o></o> <o></o> <o></o> <o></o> <o></o> <o></o> <o></o> <o></o> Yoke finished, lower mounts in:<o></o> <o></o> <o></o> <o></o> <o></o> <o></o> More to come.<o></o>
1. RFS bikes handle like a truck. (Terrible) 2. SXF bikes handle very very well 3. Not even a worked 505 can match the HP and Tq of a 600-613cc rfs 4. SXF (RF4) motors dont live long 5. RFS motors do live long.
Watching this one closely. Did you fix the frame somehow for welding or were you not concerned with distortion?
lookin pretty good. Have you figured out what makes the new chassis better? I'd like to see the frames side by side.
Rigidity. Each generation of RFS frame got stiffer. The rear suspension geometry changed as well. 250sxf 450sxf 560smr
Hopefully this solves the plumbing problem, I made it the 90 a interference fit to the down tube so i dont *think* I'll need to weld it.
awesome! I'm digging the asymmetrical frame and machining. Be sure to post lots of pics with the updates!
Thanks. I'm almost done with the chassis conversion mods. I only have to machine the SXF swingarm to fit and i'll be done. Then I can start on my other hybrid.
I ended up making line boring arbor for the swingarm, as it needs machined to fit the RFS motor. I tried just using a Drill to spin it but I had too much chatter. I ended up just chucking it in my lathe and using the carrage to push the swingarm into the tool bit. completed swingarm
I understand all of perks of the RFS motor......but the RFS bikes dont handle that bad. & 600-613cc RFS????? You are boring & stroking the thing too??? My '06 EXC handles pretty damn good. Good enough for me & I'm an ametuer/intermediate class desert/GP racer. Although I do wish I had the SX suspension on it because then my suspension guy could work major wonders (he's KTM's factory supercross suspension mechanic). Are you really good enough to benefit from all of this? With the amount of time & money you've put into it you coulda bought a spare RF4 motor. haha.
They do not handle nearly as well as the SXF bikes, additionally the pre 05 framed bikes are even worse. Yes 99mm (+4mm) bore and 78mm (+6mm) stroke Yes, If from nothing other than the susp upgrade alone. significantly stiffer frame makes a noticeable difference as well. I'm generally good on spares... Though I have less in the compete chassis than what I paid for my spare RF4 motor. Also this bikes primary use is hillclimbs (Reasoning behind the 600cc motor) not my race bike, I have a 450sxf and yz250 for that.
If its just getting used for hillclimbs....then why all the trouble for a little better suspension & a little more rigid frame? You dont really need all of the perks if its just for hillclimbs. You're putting make-up on your butthole. hahaha. All in all I actually like the concept. Thats why I'm so leary of getting rid of my '06 in lieu of an '11 or '12. I'm thinking of just investing in the SX suspension, getting it dialed & just riding it til it dies. Then rebuild it.
Good work man, it is a neat undertaking if only for the curiosity of having a project. If I had all those tools and frames lying around I'd start building frankenstiens for the hell of it, if only to irk people like the poster above.
