That's a great looking build Bruce G. Amazing, well imagined and expedited
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thanks Mick, much appreciated
got 2 of these XRs as basket cases for nothing so thought i would resto one for the viper series
been building engines for many years as i am a auto machinest by trade did some home work on the XR engine and have overcome what i think are its weaknesses
got rid of the massive flywheel and cam trigger cdi to run a inner rotor ignition off the crank
lightened the hell out of the crank and then spent a lot of time balancing it with the rod and piston
bigger barnett clutch set up
re-routed the oil supply thru a cooler and straight to the cam
modified the oil pump flow rate
running a roller cam instead of pissy original one
slightly modified the weak chain tension er set up
running a 32mm flat slide
hooked up to a port flowed head running a 1mm bigger inlet valve
hand made the exhaust myself with a bigger o/d and reverse cone
have had it running but not tuned yet
it sounds like a wrf yamaha, revs very quick
the duel map ignition has the limiter set at 11000 rpm
tuning it with Sunco C14 its a leaded fuel much easier to tune than unleaded crap
Wasp from this forum made the rear shock from scrap for me with all the late model adjustments
I fabricated a set of race tech emulators to fit the inner tubes then got Wasp to set up the springs
so with a bit of luck it should handle good
chomping at the bit to ride it