I know I've seen this issue brought up in other threads, but I'm at a loss.

I have the "hang at 4k" problem. I understand this is because the mix is too lean? Yesterday I went out and checked the pilot jets and they are screwed in all the way to a gentle seat and it still hangs. I have checked the boots and as far as I can tell there is no air leak.

Do I need to change pilot jets? Re-clean?

Do I need to change pilot jets? Re-clean?

4k is when the mains start to kick in so I would check diaphram for tears and smooth lift. check spray bars in carb.

Yesterday I went out and checked the pilot jets and they are screwed in all the way to a gentle seat and it still hangs.

Do I need to change pilot jets? Re-clean?

You screwed the mixture adjustment screws in, aka pilot air screws, the pilot jets are brass jets inside the carbs

I know I've seen this issue brought up in other threads, but I'm at a loss.

I have the "hang at 4k" problem. I understand this is because the mix is too lean? Yesterday I went out and checked the pilot jets and they are screwed in all the way to a gentle seat and it still hangs. I have checked the boots and as far as I can tell there is no air leak.

Do I need to change pilot jets? Re-clean?

Turning the mixture screws in makes it lean, to richen the mixture screw them out. Start at 1 1/2 turns and turn them out slowly until you get the highest idle speed (turn it back down to 1200 RPM as you work on it. Remember to go back and forth between them and they may not end up the same number of turns out when you get done. Once you get this done you won't have the hang problem anymore.

You screwed the mixture adjustment screws in, aka pilot air screws, the pilot jets are brass jets inside the carbs

Makes much more sense. I will check it out again this weekend.

Turning the mixture screws in makes it lean, to richen the mixture screw them out.

You sure about that Cy?, Thats different to the norm!!

You sure about that Cy?, Thats different to the norm!!

he's right.

If the pilot mix is near the engine in front of the body its a fuel meter, so opeming the jet richen's

the mix.

if its located between carb body and air cleaner its an air meter and opening weakens the mix as it lets more air in!!!

he's right.

If the pilot mix is near the engine in front of the body its a fuel meter, so opeming the jet richen's

the mix.

if its located between carb body and air cleaner its an air meter and opening weakens the mix as it lets more air in!!!

Makes sense,.. i didnt know that! thought they were all pilot air adjusters.

Makes sense,.. i didnt know that! thought they were all pilot air adjusters.

got it off CMM

got it off CMM

Ok, I can't take it anymore Drewpy, just what is your avatar there?

Ok, I can't take it anymore Drewpy, just what is your avatar there?

It's a horse skating a half-pipe.

It's a horse skating a half-pipe.

and some.....

Ponies R US

and some.....

Ponies R US

Well I backed the fuel mix screws out and the bike will come back down from 4k, although a little slowly. Sometimes better, sometimes worse.

Should I consider taking the carbs apart to clean and check floats, etc? Or just mess with the mix screws some more?

The bike's lower powerband is muuuuuccchh better now. No need to be at 4k to pull from a stop.

Well I backed the fuel mix screws out and the bike will come back down from 4k, although a little slowly. Sometimes better, sometimes worse.

Should I consider taking the carbs apart to clean and check floats, etc? Or just mess with the mix screws some more?

The bike's lower powerband is muuuuuccchh better now. No need to be at 4k to pull from a stop.

richen it a bit more, start easy and if the needles come out (too far) then its a carb strip (use ultarsonic bath)

One last job before you resort to carb strip, spray around the carb manifold area with easy start, see if the engine speed changes...Leaks test!!

I had a similar problem on an XS250 except it wouldn't come down from 3000rpm. Cleaned the carbs - no difference. Tried another pair of carbs (ebay) - no difference.

I noticed that the inlet stubs looked perished from the outside but the cracks didn't seem to go all the way through but I bought another pair of stubs (ebay), made some gaskets from gasket paper and fitted them with high temperature silicone RTV (Loctite 5920). When the silicone was set I refitted the original carbs and the problem was solved.

HTH