As I wright this I have the carb on my 95 520 H split in half.."top part removed"
I followed this thread & learned a few things.... topic 3004

I'm haveing an issue with the engine only wanting to run smooth with the choke about half way pulled up.
So I'm blowing out all the passages with carb clean & verifying all is good....

I'm curious....does anyone know if there are any adjustments on the carb?...I'm not seeing anything other than a throttle stop?
I thought maybe the fuel mixture would be off & could tweak it back it.

I did notice the carb is made in Japan....maybe I should ask the local bike shop to tune it?

Dont think you can adjust the onan carb. My brother has mentioned in the past that if you blow air through the wrong hole it blows out a part than only comes in a $100 carb kit. Without it the engine will still run but not idle.

If it is a Nikki carb, the mixture screw is on the muffler side near the bottom. It should have a plastic cap which limits you to a quarter turn. Pop the cap off, turn clockwise to seat (do not tighten, it will ruin the seat), back off a turn and a half, crank engine and adjust from there.