i just bought a trailblazer 250 when i first i got it, i could crank it up it ha a high idle..the idle screw doesnt seem to lower it any but if i back the pilot screw? (not sure which one it is but its on the back half of the throat closest to the air box) just about all the way out it would lower the idle a small portionand when i just lightly tap the throttle it will rev but come back down real slow and it if i hit the throttle hard it will rev and never come back down.. i cant kill it with the key or the kill switch. i have to hold the throttle wide open it it will die.
i just put new gaskets on the top end and supposedly the oil seals were just replaced but i havent checked that myself. after i put the new gaskets in it, it was hard to start and when it did start it did one of two things. 1. would only fire 2 or 3 times then die or it would start but would have to constantly play with the throttle to get it to stay running. left it in one spot too long and it would bog down and die. put a new spark plug in it today and it is back to square one. just like it was before i even started working on it.

 

sounds like the jetting is out of whack

 

sounds like your idle circiut is plugged and they adjusted the throttle cable to keep it idle'n
pull the bowl off the carb and remove the floats carefully and check the pilot jet thats recessed in the hole, i bet its plugged, remove it and run a cleaning wire through it , reinstall and b4 yo start it!!!... back out your idle screw and adjust your throttle cable back to where the slide in the carb closes against the idle set screw again, and you should be good to go

 

the slide comes down to about 3/16" between the slide and the carb on the bottom. this bike ran fine until till one day we were out ( the guy i bought it from was riding it), and it just lost power. it would idle and rev up but when it got a load it just didnt want to go. then it sat for about 2 months before i got it. i just bought a new carb kit for it..put a new pilot jet in it so i know its not clogged and i blew some air into the hole that screw fits in.

sorry this is eggenz7..didnt realize it logged in as somebody else

 

did you set the air srew right? is the throttle cable adjusted right?

 

does the slide need to come down all the way against the carb or is it supposed to have a gap between the carb and the bottom of the slide?
i set the air screw in all the way then turn it back out 1 1/2 turns

 

This may sound crazy, check the slide it can go in backwards, when you put it in see how far down it goes, then rotate it 360 degrees and try to slide it in again, if it goes in deeper , it was in backwards, I've seen it happen.

 

i know the slide is in correct...it can only go in one way
on the jet needle, how far in is it supposed to go into the needle jet?

 

Well if it goes in deep, its OK, but if it's like 1/2 way up it is in 360 degrees wrong, causing it to rev like hell when started, some bikes won't even start, but the few trhat have will act like that, if not, you could also have a vaccum leak either in carb boot or crank seals, if you spray carb cleaner in any of these areas and it revs, you need a new seal, that will make it act weird too. I've also seen a needle a little bent from being forced in and that will make the slide hang up.

 

ok well i checked the throttle cable at the carb, and it was adjusted way out. i backed out the idle screw all the way and let the slide go all the way down on the bottom of the carb throat. that took care of the reving. but i still cant get it started very easily. i have to turn the choke on and hold the starter and move the push the throttle in and out. the whole time im doing that the motor is firing and slowly gaining speed and will eventually start running without the starter helping it. as long as i have the choke on, it will idle (with me holding the throttle just little because the idle screw isnt set) but when i turn the choke off the motor bogs and dies. and then i have to start again with holding the starter and choking and working the throttle until it finally runs on its own.

i do need some info tho..i the air screw which way leans the mixture and which way richens it?