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yz 125 problem!!!!

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he guys i just picked up what i think is a 1999-2000 yz 125, it didn't run, look like it just needed a new top end. i rebuilt the top end, everything went in right, ive done many top ends on my 250 never having a prob. bike fires up second or third kick, runs for about 20 seconds then dies, wont fire up again, pull the plug its fouled, super wet (was a brand new plug #9), so i pulled the carb apart, making sure all setting are ok, everything checks out, from what i can see the jets look stock but no way of telling for sure, so i baked the spark plug with a torch, made sure it was working(kickin bike over with it grounded), nice bright blue spark, cleared the cylinder out, put it all back together, fires up and again only runs for about 20 seconds, and won't fire again, plug again is soaked. running 32 :1 mixture, crank and rod felt tight, is it possible this bikes jetted for different mix? only no enough about jetting to get by but found the main to be #350 and the pilot is a #45, and i believe stock is #350 #35

clearly its running extremly rich, i tried the airfuel mix screw all the way out still no luck, reeds looked fine, the guy i got it from knows nothing about the bikes history but it ran for him.:banghead:what can i do to get his thing to run!?! and what actually fouls plugs? to much oil or to much gas? would a #8 plug make a difference? and info will be greatly apprieciated thanks

Edited by j16out

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less oil in the fuel:oil ratio richens the jetting, more oil leans it out.

I'm no expert in the jetting area, however if I were you I'd just follow the jetting thread in the FAQ to set your float height, and also check that your choke is not stuck on. A good place to start IMO. See if that helps the situation at all.

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Start the bike and rev it right away, see if the needle and main jet are working OK. If the bike still runs OK at higher RPM, then its probably just the pilot system that isn't working, it could be a problem with the choke valve. When you clean the carb, make sure you pull every jet out, clean every one with soap and water, then blow them out with compressed air.

Also and maybe this is just silly... but dump out all the fuel in the tank. Make sure you put in NEW, FRESH fuel. Sometimes its just that simple!

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hey for anyone who is interested i got it figured out. turns out the float height was not properly adjusted (some one must have drop it because it was way out) then i threw a br8es in and cured the problem right up, runs beautifully now without loading up:thumbsup:

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Ours had done the same thing but was a piece of dirt in the float needle. It caused the rubber to leak fuel into the bowl and would do that at idle.

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yeah i thought it was that too, because the float bowl had an excessive amount of fuel in it and it sometimes would just start pouring out through overflow so i check but needle was clean, rubber tip was fine and insert was fine a well, would seal when i gently operated it, but turns out little tab on float assembly was bent down so far that it would barely close the needle valve when float were touching top of bowl lol

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