I have a 35mm carb on my 220 and overall it runs pretty decent but I've been chasing a low end , 0 to 1/4 throttle sputter.

Any suggestions ? I 've changed the pilot jet and needle all over the place.

I'm thinking it's too rich ,, but honestly hard to tell.

What sort of sputter are we talking about here? All 2t's will sputter when cruising at low throttle openings. They don't cruise the way a 4t will.

If it stumbles more than it should, it could be rich. Doing a plug reading with a fresh plug after riding it solely in the "sputter zone" should tell you if it's lean/rich.

I'll try it with a fresh plug.

I'm only comparing it to my son's 200 which has almost no
sputter at low end.

It doesn't run bad or lack on power , just sounds like it's missing.

What changes have you made? Any difference at all between the changes?

Im having the same problem with the stock 33 mm carb and I cant get rid of it either . I was going to try a 35 mm carb off a 200 . I cant seem to get any answers either .

Im having the same problem with the 33 mm carb . I wanted to try a 35 mm off a 200 . I was hoping that would solve the problem . I cant seem to get any answers.

Well I believe I've found the running difference between our 200 and 220 .

My son's 200 has 10.5 compression and my 220 has 8.3 compression
I was running the same fuel and Fuel / oil mixture in both bikes.

The 200 with more compression can burn the mixture just fine but
the 220 with lower compression can't at lower rpms.

What I did last night was to mix a new batch of fuel with a higher oil ratio 40:1 " I was running 28:1 " and the bike runs much better.

Sputter's not 100% gone but a great improvement.

I moved the jetting and air screw all around with no change like it
made by changing my fuel.

This winter I'll put in a new Wiseco and the head machined to get the compression where it should be.

I should have known as I ran across a similar situation years ago , many years ago and had forgotten about this.

Let me know what you find with your bike . The 35 mm is worth the performance gain but don't change it to get rid of the sputter.

Hi this sound just like my bike (2003 KDX 220 stock- I think ), I bought it about 5 weeks ago, at the time I could not ride but the bike started and reved fine all sounded good.
I have just taken it out for the first ride and i feels alful, from cold the engine felt like it was about to die if you opened the throttle it would die It felt like it was running on full choke.As the bike warmed up it got better with the high revs pulling well but low down it is very lumpy and bogged down. The plug is and 8 the gap is fine and its dry but a dark ish brown.
I have not tried pulling the carb out to clean it but I'm thinking that maybe the pilot jet may be blocked. The last owner didn't own the bike long and did not know if the last owner a changed the pipe and jets.
So any help that you can give would be great.
Jono

Try reading your other post.

The other thing That I believe may contributing to this is Ethanol in gasoline " pump fuel " . Not a good thing when you fill your 5 gallon
can that there's 1/2 gallon of Alcohol in the mix.

I just learned that the marina's have non-ethanol fuel because of so many running problems ,, the only slight negative there is it's only available in 87 octane.