Running lean

[Octo777]

My kdx 220 has an issue running lean and over heating. Have Rb mod head, woods pipe. Have 42 pilot and 145 main jet. As for needle in using jd get blue which is the richest on 4th position for clip. Air screw 2 turns out. Lots of snap but idle screw does nothing and idle creeps up any time clutch is pulled. Ride trails mainly 2 and 3 gear run 40-1 mix. I tried the needle Fredette recommended and it ran hotter. Should I increase the pilot jet ?

[SS109]

Do a leakdown test to eliminate any possible air leaks.

A 145 is a pretty small main jet what elevation do you ride at?

[Octo777]

Sea level to 1,500m.

[SS109]

That's really small for sea level and about right for 1500 meters (that's almost 5000ft for my American KDX'ers) in my experience. Plus, having your air screw out two turns is adding even more air. What altitude were you at with the overheating and lean condition? I'm suspecting closer to sea level than 1500m. You really need to jet for your lowest elevation you'll see on your ride. If you jet it leaner than that you'll end up with the overheating and lean throttle hang you have and possibly even destroy your piston or worse.

Just for comparison, I'm at close to 600m and currently running a 38pj, 150m, and CEK needle on the 3rd (middle) clip, air screw normally 1.5 to 1.75 out. If I go up to 1050m then I really need to drop one main size and probably another step down at roughly 1500m which would be about the 145 you're running. At sea level I would probably be running a 152 or 155 main and maybe go up to a 40pj.

[DonnyV]

I would check your coolant and make sure your bleeding the air out. It sounds like you're still running the 33 carb like I am, when I was running the 5 slide my jetting was 40 pilot 145 main OEM needle 3rd clip with similar mods and a little rich which I'm okay with, that's at 3000 ft elevation, definitely check for air leak and cooling system, and dido to SS

[kdxdazz]

Could be the famous leaking carb boot only diagnosed by leakdown

[John_S]

My 220 started running hot a few years ago and a new radiator cap fixed it right up. It’s been fine ever since.
A leak down test is a good idea though.