Having a hard time getting my Mikuni dialed in. I have a "pop" that occurs when running just above idle. Also, no matter what size pilot jet i run, my air mixture screw setting will not change. Just 3/4 turn out from bottom.

Anyone out there with a similar set-up have this issue?

HSR 42 Mikuni
30 Pilot Jet
160 Main Jet
97 Jet Needle on 3rd clip position

Pilot sounds too big, main sounds too small. Don't remember the needle sizes, but what comes in them works for most, middle clip, one up or one down..

22.5 or 25 pilot works for us

165 or 167.5 i'd guess on the main

OK... I tried the 27.5 and then 30 pilot jet per the following from the tuning manual...

1. If the best idle is achieved with the air
screw less than one turn out, the pilot jet
is too small and should be exchanged for
a larger one.

Since that didn't help I guess I will put the 25 back in and try other options.

Have you tried tightening the gap on acc pump? Also valves adjusted and good leakdown

I have the acc pump gap set to a little bit smaller than a credit Card. Valve lash is good. I have not checked leak down. But my top end and idle and everything else seems good.

Does is feel like a "lean cough" u got a video?

Raise the needle by dropping the clip 1 position. Should help that pop if it's lean.

As russ said,,, raise the needle and see if the extra fuel helps

I would think it's loading up because of that big ass pilot jet, not leaning out, but I'm no carb guru...

Is this a brand new carb? New jets as well?

Watched vid. That sounds like a lean cough. swap to a 170 main and raise needle. Once your dialed in better u can come down a bit on main

Also make sure you have no vacuum leaks

Down from a 160?

Down from 170

My bad, I missed that in your post. I'm out... I hate carbs and jetting.

Your crankcase vent should be fine like you have it. Rubber Boot to intake adapter or intake to heads. The bottom line is you need a bit more fuel in that spot

Where are you located?