I have a 2000 trailblazer that idles fine but when I give it has it revs up high and won't come down. I checked the slide and it is not stuck so I'm a little stumped.

 

Check the intake manifold for cracks,plus air boxes and filters need to be on. You can spray wd40 around the head gasket,base gaskets and engine case to see if engine rpms change indicating an air leak in those areas. Plus always check carb jetting if this machine is new to you.130 main,40 pilot was stock from sea level to 6,000 ft. Usually when I encountered ones like this leaking crank seals were the problem. Especially the one behind the drive clutch. You can spray wd 40 down behind the clutch cover and see if you notice engine rpm change. If seals are leaking or sucking air you can smell the penetrant through the exhaust in most cases also.

 

I think the problem might be that the air box was not on. I am working on rebuilding everything on this quad so the air box wast hooked up the air was just coming into the carb. Now I cannot test that though because the engine stopped sparking. I had been working fine in the past but it just stopped. Nothing is unplugged and the head is still grounded.

 

On something like this a cheap manual can go a long way if you don't already have one. Can help you trouble shoot the no spark condition with resistance specs.http://visit.tradebit.com/visit.php/...75/264163829/9 I have up to a 98 model on this old 250,but believe the resistance specs should be the same. Hopefully wire colors are the same also.Exciter coil: Black/Red to Brown/White 120 ohms. Coil tab to ground .3 ohms. Coil secondary,coil tab to inside plug cap 6.3k ohms. Plug cap it self can be between 4-5k on average. Plus two black wires you can pull on this. Pull the black wire from the reverse limiter first,check for spark. Then pull the black kill wire from the cdi and see if it has spark.

 

Once you get the spark back...maybe as simple as a spark plug, then check to see if you possibly have the slide in backwards....I have seen this many a time...

 

What I would have figured too as I've seen that a lot,but in his first post he mentions that slide is in correct.

 

He had stated that the slide was "not stuck". What I had said was that it might be in backwards...I have seen this many times and did it a few times myself tho many years ago. On many carbs, the slide can be installed backwards ( 180 degrees ) because the slide guide pin is located low in the carb body and slide will not go all the way down, then causes the ATV to rev like wide open....

 

I just made sure that the slide is in correctly. On this model it won't let you screw in the cap if it is not on the right way. I put on new head and crank gaskets so I doubt that is where the air leak is from. I dot find a hole in the crank case right in front of the flywheel. I dont think that this a way air could get in and make it run like this but I may be wrong. I don't think this is the problem because it idles just fine at first it's only once I give it has that it takes off. Wouldn't it take off as soo. As I started it if it were big air leak like that. The hole is about an inch in diameter.

 

Entirely possible that could be the problem.IF crack is on the crank case itself,THEN you've found the problem!Again crank seals,engine cases,intake manifolds,etc can be the cause. Best way to narrow anything down is by a leak down test. You might get lucky by hitting all around with wd40 and see if you can narrow it down. If that doesn't work,then a leak down will help. Several different videos on 2 stroke leak down tests on you tube along with different ways of doing it. Main thing is to not have too much pressure or if the seals(if good) can pop out. Plus if there is any way to use something like JB Weld 5 minute epoxy on the crack,try it and see if that enables the engine to run correctly. Epoxy isn't meant to be a permanent fix,just enough for a test.

 

IF this hole is just a factory hole that many have on the inner case,no this wouldn't be the problem.