72cc BBK first ride

[phatboy]

thing about contra springs, a 2000 rpm wouldnt that be like popping the clutch? better take off on a motorcycle but isnt it bad for it?

I bought a tach so i can tune this better, should be here in a week or so. its an analog tach not sure where i'll mount it yet. didnt like the digital tachs even the expensive ones update too slow.

[baddi]

lighter weights faster speed heavy weights slower speed.

I lost a significant amount of torque when i got below 6g and above 7,5g.

6,25g seems to be the ideal for an unmodified agility, but if it is only the bore that has been modified, then the ideal rpm should be the same, if not a little bit lower, as it is mainly the camshaft that decides the ideal rpm, but length and diameter of intake and exhaust has also got something to say.

[phatboy]

rode it 30 miles today

with an 88 jet it goes 22 up that 20 mph hill. think i'm closing in on the correct one, but top speed is down on the flat to 39, was 43.

weird thing, it has more power at like 95% throttle than WOT. does this mean jet too rich or lean?

putting on heavier weights tomorrow, scoot is revving 9000 rpm just about any time at WOT and I think thats the rev limit in the cut CDI? what is the (approximate) ideal rpm for 72cc BBK?

[phatboy]

i put 8g rollers on, revs are definitely lower takeoff is slower but overall acceleration is about the same, still 22 up that same hill, pretty disappointing, but top end is back

might try to mix 8g and 6.5g for 7.25g, is that a good idea

or what about a race cdi, will that help too, they seem to be pretty cheap

[phatboy]

did air tube mod and upjet to 95, top end is back now, motor just needed to breathe

bottom end is still sluggish, 22 again up that hill, going to try swapping rollers

i assume for the cvt we are shooting for peak hp rpm when ever possible, its 7500 on a stock 12" A50 or 8500 on a 10" A50

what should I shoot for on a bbk with stock head, 6500? 7000?