Rubbermount_EVO Jetting 42 mikuni

[061275r]

Got a hsr 42mm carb on an 06 883r converted with the basic 1275 hammer kit with 505/515 reaper cams and stock heads bike runs good but running a little lean I put the carb on right out of the box with no rejetting just tuned in with air fuel screw. Was wondering what jets to put me a little closer to where I should be. Live in berks county Pennsylvania. Thanks

[1Scooter]

Ya should have read the set-up instructions. Here's what's in my Wife's 04 1200C: 17.5 idle jet, 165 main jet, needle middle notch, 50 pump jet, float hight 0.70. Mixture screw IN rich, OUT lean.

[061275r]

I read them just wanted someone else’s input if anyone else had a similar set up as mine since it didn’t come with a jet kit. I ordered the jets for it so I guess it’s time for some tuning. Your wife’s motor all stock besides the carb or?

[061275r]

Thanks for the input too

[JB in NC]

With the Mikunis you have the luxury of just raising the jet needle, by moving its clip down a slot or two. No jets needed for that first step. Just take the top off the carb, reach in with a ball end Allen wrench, and loosen the clamp screw, and swing the clamp out of the way. Then pull the needle out with some (wait for it) ...needle-nosed pliers. Move the clip, and put the needle back in. That will richen the mixture through most of the operating range.

If you feel that it is lean off-idle, a change of the pilot jet is in order. These are available in 2.5 increments, so for instance if it has a 25 pilot jet, you could go up to 27.5, or 30 if the first change does not get it.

Main jet may well need no change; wide open testing after the other changes are made will tell you. Read your plugs for these tests. Or read your time slip for trap SPEED if testing at the strip.

Jim

[061275r]

Thanks jb I’m new to the mikunis read nothing but good things appreciate the input

[sungod]

Originally Posted by JB in NC

With the Mikunis you have the luxury of just raising the jet needle, by moving its clip down a slot or two. No jets needed for that first step. Just take the top off the carb, reach in with a ball end Allen wrench, and loosen the clamp screw, and swing the clamp out of the way. Then pull the needle out with some (wait for it) ...needle-nosed pliers. Move the clip, and put the needle back in. That will richen the mixture through most of the operating range.

If you feel that it is lean off-idle, a change of the pilot jet is in order. These are available in 2.5 increments, so for instance if it has a 25 pilot jet, you could go up to 27.5, or 30 if the first change does not get it.

Main jet may well need no change; wide open testing after the other changes are made will tell you. Read your plugs for these tests. Or read your time slip for trap SPEED if testing at the strip.
+1


Jim

[wrkdWS6]

One of the most reputable HD tuners out there (Dave Stoddart at JD’s Cycle) happens to be over in the Lehigh valley. 2-3 hrs on the dyno at $100/hr would get it spot on from a AFR and timing perspective. He did my 1275 bike with HSR42 and my 140 wheel Softail. Something to think about.

[brucstoudt]

^^^ can you be more specfic with the location?i'm familiar with the lehigh valley but that will just get me close.

[061275r]

Thanks for the info I’m gonna check him out for sure man.