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02 WR250F new owner starting issues

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Hello, I've been working on this bike for several weeks replacing the kick start shaft and put in auto decomp cams. The bike sat up for several years so I went through the carb and replaced most of the jets to YZ specs, drained the tank, put in fresh gas, new plug. Now i'm trying to start it without much luck. I thinkI am flooding it. I got it to hit a time or two. I don't know where the idle screw is set so I screwed it in a turn or two. I know i'm to keep my hand off the throttle. The last 4t i onwed was an XR400 and if it didn;t start the first kick or two it was a bear to get going. Any advice out there?

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Screw the idle all the way in and screw it out for 1 1/2 turns.

As soon as the spark plug is dry, start kicking it w/o the choke and put the choke in after a few tries.

Chris

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Oh yea I did add a tusk mixture screw so that will be easy. If I screw in the idle knob will that cause starting issues? I was afraid the idle was backed off too far and since I can't blip the throttle like a 2t it would never start.

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If you think you have flooded it....turn off the fuel tap, open to full throttle and give it a few kicks to clear the cylinder, then turn back on fuel and try again :-) Good luck.

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Turning off the fuel won't do much, you will still have fuel in the bowl. However, if it is flooded, you can SLOWLY open the throttle fully and give it a few kicks. By slowly opening the throttle you are keeping the accelerator pump from squirting a fresh jet of fuel in there making matters worse. By opening the throttle all the way (at low, or no RPM), you are reducing the vacuum over the jets so they don't suck in as much fuel, creating a leaner mixture.

Remember that the fuel screw goes opposite of most 2 stroke carburetors because it is regulating mixed fuel, not the air for the mix.. Screwing it in makes it leaner.

Have you checked the valve clearances? Just because they were good with your old cams doesn't mean they are good with your new ones.

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I held the throttle wide open and kicked and it hit maybe two times. The valves were set with the new cams. I'm fairly certain the timing is set right. It will be this weekend before i can get back over to storage and try again. I just want to have a plan. It has good compression so i guess it will just take some time to sort out after all the things i've done. I tried to push start but I was by myself so that didn't work out too well. Thanks for the help everyone!

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are you giving the bike 2-3 squirts with the throttle, choke on, dont touch throttle again? If all is well, it'll fire

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No I didn't give it any squirts for fear of flooding. Never owned a pumper carb before. I will try two squirts and choke. Makes sense now I was worried the idle level was set too low to get fuel/air but with a few shots of fuel it should light.

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Okay, I finally got a chance to get back on this today and recheck the cam timing and check for spark. Everything looked good so I put it back together but by that time the sun had gone down. The house where I store it is on a hill so pushed started it and got it to crank up finally. It would only run on choke at first and later would run off choke but backfire so put back on choke and ran it for a good 5 minutes. The longer I ran it the better it ran off choke. I still had to push start it when warm. At least I have it narrowed down to the carb now. Seems like a lean condition. The history is that I replaced the cams and exhaust to YZ parts and all jetting to YZ specs. I spent about two hours cleaning the carb and thought I had everything clean. Are there any specific areas of the carb I should concentrate on other than the pilot circuit? I'm going to try and ride it a little next weekend before I pull the carb apart again. This is the first time the bike has run in about 5 years. Compression seems good and valves where set with new cams. It actually seemed to run good with the choke on but I had to keep it reved or it would stall. Seems like the classic case of pilot jet clogged but the pilot jet is new.

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Check to make sure you didn't install the slide plate upside down in your carb. Did this once not realizing it and it will cause all sorts of starting and running problems. Erratic idle or no idle and excessive backfiring.

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I think i got it all back together right but I will check the slide plate when I take it apart. I have never owned a flat slide pumper carb before so I very well could have it on wrong.

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You can't just put YZ jets in a WR carb. The WR has a different carb with that diaphram doohickey on the side that richens the closed throttle mixture on decel. It also uses a very different leak jet. I'm guessing that you didn't take this into consideration. If you still have trouble, clean the heck out of the WR pilot and leak jets and put them back in.

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Sounds lean to me. Are you sure you got the pilot clean out? If no, replace it. If yes, then adjust the fuel screw, and if you end up at more than 3 turns out, bump it up a size.

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