I have a HQ 120". Curently running a PSI big air carb, not totally pleased with some issues it has. I have messed with it for a good while and gettig a little tired of it and thinking about going to Mikuni 45 or 48. Does any one have any experiance or suggestions for a engine this size? Thanks in advance.

 

A 48mm Mikuni will do the job. I've been running a 45mm on a well built 95" and it's the best performing carb I've ever used. It's dependable, no flat spots, and unbelievable throttle response. Over the last 38 years I've used S&S, S.U., Weber, Tillotson, Kehin, and Bendix carbs on various hot rod Harley motors. These HSR Mikunis are tops IMHO.

 

I spoke with Kevin @ HQ about a 120" build a few weeks ago. I'm currently running a 45 Mikuni and asked him if I could continue using this carb with a 120". His response was "Yes." He went on to say that the 45 has plenty of needle/jet adjustments in it to suffice for this motor. I do know that a 48 is a bit more pricey and getting the parts for it is a little harder.

 

I have a 45mm for my 124" S&S.If you want crispy low to mid range performance the 45 is the way to go.