My bike runs like poop.. :(

I have a 2006 yz250f that is not running right.. i put it away last winter with all the stock jets and stock everything and it ran well.. how a stock yz250f runs. Anyways i put a pipe on it along with adjusted the valves over the winter along with putting in some new jets, i put a 175 main in from a 182, a 55 leak jet from an 80, and changed the needle clip from the 3rd to the 4th along with the o-ring mod. Now it is breaking up down low and running like crap, once it gets hot and dies it will not start! I chanced the clip back to the 3rd position since i figured it could be starvin for gas, did nothing. Took out the o-ring, did nothing. Now im left with the only other 2 changes leaning out the main and smaller leak jet.. but these both make since and wouldnt cause this problem i dont beileve, i dont want to change my leak jet back because everyones running 40-55 leak jets.. Anyways sorry for the long post hope someone can help! Thanks in advance!!

Just want to put a post here so I can keep track of this one. A buddy just had the same problem with his. I think it was bad gas. Did you drain all your old stuff before riding?

His blew a spark plugs tip off. Did you check/change yours?

I would think with the new exhaust you would have to go up in Jet size to accomodate for the increase in air volume going thru the bike.

Again, just my uneducated thoughts.

Yea the gas tank was completely empty when i put it back together along with a drained the carb i ran about 5 tanks through the bike since, I also have a brand new iridium plug.. im pretty stumped on this one.. maybe the plug? Just thought of that.

Leak jet is not you problem.

Once the bike was heated up, did you reset the fuel screw according to the perscribed procedure?

Did you check the float height? Was the slide out of the carb?

Did you change anything else on the bike?

Yes ive been playing around with the fuel screw constantly the other day when i was adjusting it it seemed like it wasnt doing anything then all of the sudden the idle went abnormally high and sounded great so i turned it down road it then it still dosent feel right..

Playing around with it and then getting a hanging idle is not the correct method. How about the other things I mentioned?

Fuel Screw/Pilot Jet

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.

Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

Alright cool! Thanks alot man ill play with it some more today, it seems like its starting to run a little better but once im idleing or riding through ruff woods and it stalls it does not want to start. But i know that has something to do with a mis adjusted fuel screw so ill play with it.. Thanks again

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