Has anyone got a running bike with a VM38-9? I could use a bit of assistance. I just bought a '75 Norton Commando MkIII that's been beautifully restored but barely runs at the moment. It has a single VM38 on it. It will run when choked, but won't come close to idling with choke off, and will only run (roughly) if I keep it over 4000 rpm. Since I don't know the bike, have never seen it run well, and don't know Mikunis, I don't know if jetting is close or way off.
Carb: VM38-9
Main jet: 330
Pilot jet: 30
Needle jet: 159 P-2
Jet Needle: 6DH3
Slide: 1.5
Needle valve: 3.3
Air jet - I don't see one at all. I see 3 drilled passages on the intake side, one at the bottom and the other 2 to the right of that. Middle one is plugged. Bottom one is ~4mm passage with a ~1mm hole deep inside it, but no jet in it . I think there are fine threads down at the bottom of the passage, very hard to see in there.
We're in Vermont - low altitude.
I'm hanging with the guys from the Classic Bike Experience in Essex Center VT - very nice guys, pretty new shop that's starting up very well - lots of interest, customers, nice bikes. The bike's over there now, and they're pretty interested in this, as we're sure we'll see lots of Mikuni conversions come in - there a bike there now from Colorado Norton Works, but it's got a 34mm on it.
Any advice you can give me on setup and jetting of this carb would be tremendously helpful. Thanks - Peter