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mikuni tune

Well have done all the above. Went to a 20 pilot and wouldn't idle well at all when cold (acted like it was missing). I put in a 25 pilot and a little better (idles fine when warmed up). I put a 50 in for the accel pump and moved to right off idle. And have a 165 in for the main jet. I haven't messed with the needle at all. It acts like it is missing when first started up (no choke). But idles fine when warm. Pops some on decel, which it wasn't doing with the 30 pilot. It seems to run fine when warmed up, roll off method says main jet is OK. But still terrible gas mileage. I am stumped. Timing, curve what??????? Want to go on a long trip without stopping for gas all the time, but not sure what to do next.
 
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Did you replace your intake seals when you installed the carb? If not, shame on you. And btw, a lean running carb will also have terrible mileage.:bigsmiley22:
 
98fat said:
There is alot of information on here and elsewhere on tuning a Mikuni including their tuning manual. I have already read all I could find. BUT, I am going to ask this question anyway. I have a 98 Fatboy, Dave Makie cam (similar to an Andrews 27) Vance Big Shots two into one exhaust and a K and N high flow filter. The bike seems flat when I am accelerating, but idles fine. Terrible gas mileage. Seems to surge when I do the roll off test which says lean. But that doesn't measure up with the bad gas mileage. Thoughts???
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I wish I had seen this thread when it was new.
This person was suffering from too much cam for the riding he does.
A 27 cam is low to mid cam which should roll on fine.
The pipe he used is a low end pipe and should give decent torque.
For the mods he chose, all he needed to do was to go up on the low speed jet and tune it to 1.5 to 2 turns out.
The main should be left alone.
The needle jet is fine but the needle should be raised 1 notch.
That should of made it run just fine.
 
Well just an update for those of you who might need to tune a Mikuni. I have it about as lean as you can get without being too lean. Plugs are OK. Running 50 accel pump (right off idle), 20 pilot (about one turn out on the adjustment) 160 main and 98 needle middle clip. Getting low 30's on the highway. It starts good, runs good performance wise probably as good as I am going to get mileage wise. Cheers:D
 
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