Just ordered some new parts for the Fatboy.
-Mikuni HSR42 carb kit
-Arlen Ness Billet Sucker Stage II
Im hoping this will give me a little increase in power and smoother operation. Already have V&H Longshots. This carb should also support the head work and cam I plan on doing later. Ill let you guys know how it goes. Should be here next week!

 

Sounds good. Mikuni is a great carb for sure.

 

I've been using one on my FLSTN since '02. It improved starting and the throttle rsponse and driveability is great. The drop in fuel economy compared to the CV carb is not so great. Even with "economy" jetting per Joe Minton, I can't get anywhere near the fuel economy that I could with the CV carb.

 

Good call what sort of dollars man?

 

Before you install it check the float level, they have a tendency to be off a little due to rought handling. A high float level will reduce mileage. Also check the accelerator pump clearance. It should be .080" to start, you can customize it from there.
John

 

Good carbs, recently got a 45 dialed in, had a good CV and give the nod to a Mikuni. Did a 50 accelarator pump jet / tightened up the travel gap, lowered the small jet and dialed the needle setting and main jet in with a AFR reader with a result of accelleration and believe it or not, better fuel mileage than the CV.
Noticed that the Mikuni ran off the small jet going down the road and a simple screw turn would control cruise AFR's where the CV depended more on the needle for cruise range and more difficult to make cruise range changes. Set up at 14.2 cruise, 13.2 WOT and smooth as silk with the 97 needle, very happy with the Mikuni. A little note is the Mikuni ran no better than the CV until I got the AFR's dialed in expecially at wide open throttle so tuning is everything.

 

I dropped the pilot jet to a 17.5, then back to a 20, put in a #50 accelerator pump and closed up the gap and went to a leaner needle. Bike runs great but fuel mileage is still in the range of 42-44 MPG.

With the CV and a #45 pilot jet I averaged 50 MPG.

 

Uncle G, the CV I was running had all of the tricks done with 48 & 205. dumped fuel at roll on but cleared out quickly and ran great, also was insurance with roll on detonation so I left it alone.

You might try a experiament and turn that screw out 1/16 of a turn as I mentioned that the Mikuni runs at cruise off the low speed jet by a digitial AFR reader and see if the mileage increases. Have a 20 low with a healthy engine, can get 14.2 cruise with a very very little exhaust pop off the 20 low speed adjusted off the air mixture screw. 1/16 of a turn can change .6 AFR at cruise which adds up on a trip, don't know if you can hit 50 mpg but anything helps.

 

John a minor tip I give to guys going to a Micky is to tune with the accelerator pump disabled, they get no false readings and then when the jetting's wired tight bring the pump back in to the system.

 

WE did that so you could tune it like an S&S in the old days. Now we've done so many we do it with the pump on unless it is an all out engine, or we are having problems with the combination.
John