78 Or390 Carb Question - Float Arms

First time posting on the site. I purchased this OR390 a couple of years ago in decent shape. It can be made to run and when it runs, it runs pretty well but it is a @#$% to get started. Hence I haven't been able to ride it much. I've now decided to get this resolved once and for all.

The carb is a 38mm Mikuni VM. I've cleaned it thoroughly. All jets are and passageways are spotless. The only problem I encountered was removing the Air Jet. Someone had buggered up the screwdriver slot so it presented a significant challenge to get out but I did.

My question is this:

I do not know which direction the float arms are supposed to go. A photo in the Husqvarna Service Manual shows it arms up. There is another diagram that shows it going arms down. The diagram in the parts manual also show it oriented arms down as does every Mikuni drawing I can find. I do not know which is correct. I have it installed arms up as shown in the service manual photograph.

I figured that setting the float to the correct height would make it clear which way is correct but it really doesn't.

Any help would be very much appreciated.

Thanks in advance.

I’m not too much of a help here ... but there’s some drawings on this site www.frankmxparts.com Frank would most likely have the answer .... he has helped me lots on my Keihin ... but he does know the Mikuni as well.

Float arms down as pictured, as in your top picture.

Thank you very much for the reply. That is how I installed them but I wanted confirmation from someone who with knowledge. I really appreciate it.

As a note to anyone looking at this in the future with the same question, the arms are actually "arms up" as the carb is shown upside down in the top photo. While the arms are "Arms down in the photo, they would be upward when the carb is installed on the bike.