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urgent help with some jetting trouble

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SO i got a 2007 250sx setup for trails and im having the hardest time getting the jetting dialed. I go away to college so only get to ride during breaks which means not very often. I got a JD kit that seems to help but I think I am running rich because I am having trouble wit the bike starting when warm. I will put a new plug in or let the fouled one sit and it starts fine with the choke on. Then ride it for awhile in the driveway and if it dies or I turn it off, I cant get it back going again without a new plug or letting it sit for awhile. There is some spooge coming out of the end of the exhaust too so I think I am a little rich but can I fix this with my air or idle screws?

Its also smoking quite a bit but I dont know if thats just because it hasnt been ridden since thanksgiving or what.

Per JD's instruction I am running:

40 pilot

162 main

Blue needle in the middle position

40: ratio

alt about 500 ft

Currently high 40's in temp.

I guess the main thing I am curious about is how to the idle/air screws control the richness/leaness of my jetting. JD said to run the air screw 1 3/4 turns out so I am doing that. I got a ride planned tomorrow and haven't ridden since thanksgiving! I dont want to have to keep changing plugs all day

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i tried....called right after they closed. I am trying to go riding tommorrow since it is my spring break so I can't really wait till then.

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if its been sitting very long the pilot jet may be plugged or partially plugged. The stops then starts later could also be the gas tank not venting and is creating a vacuum. Check the valve in the gas cap. Blow thru it and see if it lets air thru. Its common to disable this feature and just remove the check ball.

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i cleaned all the jets and put new ones in anyways before even starting. It only stops when I am riding it and let it....either by choice or by trying to get the idle right. The problem then seems to come as it wont start again whenever it stops. Could leaning it out with the air screw help? out would be leaner right?

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put the blue in the 2nd clip drop the pilot to a 38. I have yet found any good conditions to run the 40 pilot. It is cheaper to error on the rich side but when your talking fouled plugs you are way rich.

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well i went to go riding today with a fresh plug and the thing wouldnt start....tried changing the plugs twice and nothing. I put a little gas in the cylinder after each plug because I was told this can be a sure fire way to get it to start but I think that may have just added to the problem. I think there is just a lot of oil crap in there from running so poorly and being flooded. Along with the fact that I havent been able to ride the thing hard, which I think it needs most. Oil was leaking out of the flange where the exhaust comes out pretty bad. SO i drove home all bummed and after taking the bike off the trailor it started second kick. Rode around for awhile then put it away....came back and nothing. I then changed the plug and took the exhaust off to look at the piston and there was a little spot on it of what looked to be spooge or carbon that was smeered up and down on the side of the piston. I will upload the pick I took of it. Anyway the thing started right up. and i rode it hard for awhile up and down our driveway and my short trails. However it still did not want to idle.

Any other ideas? I am thinking maybe I need to switch to the 38 pilot like was said. I started my old 250f thats been sitting for 6 months and the thing started 4th kick and ran strong....just wish my bike would run that way.

heres a picture of the spot on the cylinder I was talking about. It is on the left part of the cylinder. It turned out horrible which is wierd since I have a good camera. Most of it I can just clean off but the dark stuff is stuck an there...kinda feels like carbon

CIMG1134.jpg

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If you have the owners manual it has a great jetting chart that I have had great luck with. Why is it you are using the JD jet kit? I think they are a good product but more so in the fourstroke world. If you have the stock needle and jets, try those with the specs in the manual. I have a 07 250xc that was all messed up in the jetting from the previous owner. I bought some jets, followed my manual and it worked great. Is the bike stock or has it been piped, different silencer, reeds, and so on. That all makes a difference. I run a 168 main jet, 38 pilot, n8rg needle, clip in the 3rd position and my air screw 1 turn out.

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You do realize that you can rebuild the top end? and you should test for

compression.

did you lean out your jetting? your issue is jetting or compression or both.

more than likely its just jetting. lean er out and ride it like you stole it.

the richer jetting causes the bike to run cooler and the excess premix makes a mess of the top end but lean it out and ride it and if your compression is good the carbon and spooge will burn off.

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i think i got it running better. I rod eit har din the yard a lot and it restarted twice and ran hard after each time. I think it really just needs to be ran hard. I think I made it worse at the riding area by putting in some gas in the cylinder as someone told me to do it before and it always worked.....but I think that is more for when th ebike has sat for a long time and the carb might be plugged up. Lesson learned.

Do 2 strokes not sit as well as 4 strokes for long period of time? My old 4 stroke and our 250f have always started after a couple kicks even after sitting for over half a year at times.

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i think i got it running better. I rod eit har din the yard a lot and it restarted twice and ran hard after each time. I think it really just needs to be ran hard. I think I made it worse at the riding area by putting in some gas in the cylinder as someone told me to do it before and it always worked.....but I think that is more for when th ebike has sat for a long time and the carb might be plugged up. Lesson learned.

Do 2 strokes not sit as well as 4 strokes for long period of time? My old 4 stroke and our 250f have always started after a couple kicks even after sitting for over half a year at times.

as long as you drain the gas and burn off the excess, you should be good. But, sometimes gas goes bad. If you haven't really had a chance to clean it out and running too rich, you are depositing a lot of gunk in there.

Even when lugging thru the woods for long periods, I occasionally pull the clutch and rev it out to clean the system out.

you aren't burning oil in a 4 stroke.

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yeah i always drain all the gas out the carb and have been getting new gas during each break I have from school and come home. I think I may have had a lot of gunch in there from earlier bad jetting and it needed to be ran hard to get rid of it. I ran it real hard in the yard yesterday and she started much better after this. Theres no more bog at 1/4 throttle. Unfortunately it will be sitting until may again and I didnt get a chance to ride the thing hard for the day.

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