Finally got my 700cc top end rebuilt project to a good intermediate pausing point. Earlier this year, I fitted the 700cc (697cc) JE piston kit and a Shell#1 cam from Hoos. The head underwent a cleanup, 'street porting,' and had Kibblewhite valve springs installed by Roger at R&D Motorcycle Service. I also upgraded to Vesrah clutch springs and new EBC friction plates. Special thanks to 5twins and Michael Morse for their help in tuning.
Below is the result with the following configuration: (correction on displacement 698cc)
The current setup gives just under 50hp, hitting 50hp in one unrecorded pull.
And here is how this compares to the stock measured on the same bike and same dyno a year and a half ago (Nor Cal Cycles in Millbrae, CA http://www.norcalcycles.com/service.aspx):
there's a 17% increase in peak torque and hp. Considering that Hoos 700cc race bikes dyno at 55hp and 44 ft-lbs of torque, I am happy with the result. The bike feels completely different, very responsive, and fun to ride. But, there's fine-tuning left: fixing the dip in torque at 4K by leaning it out (will try 5Z1 needles, as suggested by 5twins). I also plan to slightly widen the headers for better top-end performance.
One may ask why I am using stock headers. Initially, I tried 1.75” pipes with torque inserts, but they caused excessive exhaust reversion, making the bike run rich beyond 4.5K rpm. Even adjusting the main sizes and dropping needles didn’t solve it. Only switching back to stock headers with the much lower pipe internal diameter allowed to scavenge the exhaust better, leaning out the A/F mix and bringing out the performance gains.
Next I will fit 1 3/8" ID torque optimizers from Michael Morse to the 1.75” pipes and may open up the intakes.
Below is the result with the following configuration: (correction on displacement 698cc)
The current setup gives just under 50hp, hitting 50hp in one unrecorded pull.
And here is how this compares to the stock measured on the same bike and same dyno a year and a half ago (Nor Cal Cycles in Millbrae, CA http://www.norcalcycles.com/service.aspx):
there's a 17% increase in peak torque and hp. Considering that Hoos 700cc race bikes dyno at 55hp and 44 ft-lbs of torque, I am happy with the result. The bike feels completely different, very responsive, and fun to ride. But, there's fine-tuning left: fixing the dip in torque at 4K by leaning it out (will try 5Z1 needles, as suggested by 5twins). I also plan to slightly widen the headers for better top-end performance.
One may ask why I am using stock headers. Initially, I tried 1.75” pipes with torque inserts, but they caused excessive exhaust reversion, making the bike run rich beyond 4.5K rpm. Even adjusting the main sizes and dropping needles didn’t solve it. Only switching back to stock headers with the much lower pipe internal diameter allowed to scavenge the exhaust better, leaning out the A/F mix and bringing out the performance gains.
Next I will fit 1 3/8" ID torque optimizers from Michael Morse to the 1.75” pipes and may open up the intakes.
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It's now more enjoyable on the street. I've added 15K miles to it now, it's a bit tired, but no internal parts have found daylight... I may just ride it one more summer before opening for a refresh and measure to see what actually lives inside it.
