Quote:
Originally Posted by kregan1
ive been trying to dial this mikuni in on my 113 ultima. started out with a 25 pilot jet worked my way all the way up to a 35. the 27.5 has given me the best results but i am still getting backfiring on decel out of the exhaust and a cough out of the carb at low rpms gettin on the throttle. i put baffles in my drag pipes and hate them now, but it did improve it, im also thinkin the fact that my rear cylinder exhaust is so much shorter than the front cylinder pipe may have an effect on this as well? un equal back pressure due to different length pipes?
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No, it's the bump stick numbers.
causes lean out during throttle shut down
I have to some extent on my 127
Completely re jetted my 45 to reduce it but could not get rid of it
32.5 low speed 1.5 turns out on the screw
the richest needle they got in middle clip position
the richest needle jet they have.
and I run a 185 main (could go to a 182 I think)
when air temp is high, almost no pop
when air temp is cool, some pop
tested with 3 different types of pipes RB racing, V&H pro, V& H big shots
still the same.
Basically all the jetting from a 48 mik.
the port velocity in those heads is real fast and when that exhaust closes, pop pop pop
I've learned to crack the throttle ever so slightly when I want almost no pop.
I think what Ultima motors need is that Big Air carb
probably the hot set up
no jets, just click adjustments in three throttle zones
just wont crap out that much money for a carb
Linear Mode
