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There are so many variables, target rpm and alt are huge as is how hard you want to load the engine. Loading the engine requires more fuel etc. etc. etc.
Gearing and making the primary and secondary work together is the key and there is at least 20 set ups that will net the same rpm. Its really has more to do with how much you like to tune to make it run perfect every ride out.
Most guys want a ball park pull and go set up, I want it spot on every ride
and will change a helix and or springs/ weights if needed twice a day to have it perfect.
My 990 preffered set up was 20/46 gearing, 265-310 primary spring, 64 gr
heavy toe weights ground down from 69s, 55/53 helix with red white cat spring in the second to softest setting. When I needed more rpm I would go 1
hole tighter and/or change to a 53.
This set up was at 8,000 to 10,000 ft shooting for 8250 rpm. I ran jaws twin race pipes and pulled 520 mains.
Mike
When you guys talk about choking down, Is this done at the end of the stingers/muffler? Or is it where the pipes mount to the head?
Thanks
Mike
do you think 32.8mm is too tight on the d's?
I'm running cpc 48 with 540N mains and just looking for any input on combo. head are loose just above 60 on the squish on a 990
clutching on the 975's?