KX500 powered RGV250

[NordieBoy]

from a '79 XR500Z you can get at least 70hp, and does a 4 stroke not generally have more torque? (Always interested in this stuff!)

But are you allowed to run methanol in F3?

[pete376403]

My old C20 with the Jap A series copy only had single plugs. Was a lot better when we added my mate’s home made transistor module onto it. Problem was it would run just fine until one day it would refused to start, and then you’d have to open the contacts up a bit (by eye), felt just fine until the points wore against the cam & kept closed. That cam would always get a bit dry. (Not sure what a CA20 is, probably don't care, I'll keep the HiAce).

I digress. The twin spark was just to reduce the length the flame had to travel over such a big cylinder. The staggering idea is interesting too but newer CDIs allow a longer burn time then the early ones. While the longer burn time will def help cold starting etc at low revs, at highish revs I doubt there would be any influence & the detonation is the problem that causes the issues.

Nothing new under the sun. Bruce Abernethy ("Abbo") an NZ speedway rider back in the '50s had a twin plug JAP. Had had a special timing side mount made with two magnetos, one in front and one behind the cylinder. The mags were timed to fire staggered, and the bike was reputed be be unbeatable out of the gate. he JAP (and 2v Jawa) had a very large. thin, hemi combustion chamber and the piston dome more or less filled the head completely. That and the difficult to ignite methanol meant that bikes would occasionally misfire at the gate. Abbos twin ignition pretty much fixed that. I bought an engine off him which had the 2 plug head, but not the magneto drive. Swapped it for a nice reliable Jawa

[geoffm]

Guy I bought my Impulse off in the early '90s in Hamilton was building a Kx500 into GSXR400 frame thingie at the time. I think the motor went back into the KX after a short time.
I remember someone had a KX500 thingie at baypark when I used to race there in the mid '90s. IIRC, he had vibration problems. The exhaust came over the top of the motor to try and have a fat pipe with ground clearance.
Geoff

[geoffm]

Guy I bought my Impulse off in the early '90s in Hamilton was building a Kx500 into GSXR400 frame thingie at the time. I think the motor went back into the KX after a short time.
I remember someone had a KX500 thingie at baypark when I used to race there in the mid '90s. IIRC, he had vibration problems. The exhaust came over the top of the motor to try and have a fat pipe with ground clearance.
Geoff

[TLDV8]

It would probably be worth going to rubber mounting for the engine with something like the Suzuki GT750 uses if it was being done from scratch. (fwiw)