Motor revs way too high on its own?

Drek232000

New Member
Apr 1, 2009
8
0
0
Bothell, Washington
I have only had my blsters for a few weeks now and have only been out riding 4 times. Today one of my blasters went crazy multiple times and I dont know what is wrong with it and why it did it. But i was just sitting at idle trying to figure out where to go next on the trail and the engine reved up super high so i hit the off switch it did nothing then I tried the key it did nothing I thought for sure the motor was going to blow up right there because it was at such a high rpm for so long. Finally i cut off the gas supply and it stopped. But, what could cause this and is it a easy fix. Could it be the throttle getting stuck a carb issue? I just don't know where to start but am scared to keep riding it because if it does that while im moving im gonna die. Any thoughts would be great. By the way it seems like it settles down and is fine when it is in gear its more when it is idling in neutral that this occurs.
 
I think you should adjust your idle screw because I had the same problem with my blaster when I first bought it. Every time I sat at idle it would rev up and in order for me to cut the motor off I had to put it in gear and drop the clutch while holdeing the brakes.
 
An older blaster of mine kept doing that once,take the carb off and clean it.Make sure everything is adjusted right,float level,cable tension,and air screw on the carb.That's what I did and it stopped for good.
 
Thanks everyone for your ideas and thoughts on what it is. When I get some free time I will take a look and see what I can come up with off of your ideas. The motor was rebuilt by the previous owner less than 10 hours ago because the oil injection kit failed. So, I am thinking that it just was never tuned correctly once he got it all back together. Hopefully it will be a easy and free fix I have been spending a lot of money on these things lately.
 
I went out riding hard the other day and when I would pop into neutral to take a break mine would rev out of control! I would have to cut it off for fear of blowing the engine. Its your idle screw and your throttle screw, they need the right combination to work together, I turned my idle down some and it hasnt done it since! Idles and calms down as it should, so adjust your idle or air/fuel screw on your carb and your throttle screw under the seat to find the right combo, and it wouldn't hurt to clean your carb, it did mine wonders!
 
An airleak could cause high revs.

Right an air leak or low fuel situation will cause high revs BUT that wouldn't explain the kill switch and key not working... I'd venture to say tors is screwed there's an air leak and an electrical problem from what he described.

WHY didn't you pop the clutch and hold the brake to kill her?
 
Right an air leak or low fuel situation will cause high revs BUT that wouldn't explain the kill switch and key not workingQUOTE]

If the case or head/cylinder have a leak the engine goes lean at idle and gets hot causeing it to run away... At this point the hot spot in the combustion chaber is igniting the fuel not the spark plug.

Does it detonate at idle?
Does the idle speed adjuster do anything when you turn it?
Does it keep running if the idle mixture screw is turned in all the way?

You should do a pressure test to check for leaks. I rebuilt my blaster and after 15hrs. or so it started leaking around the base of the cylinder and did the exact same thing. I could stop the run away by fiddleing with the idle mixture but it was still running with a air leak. Not good in a two stroke!
 
Just want to say I just got an 04 Blaster and it was having a simular problem with the high idle.....adjusted to tors and it is fine now.....so glad I found this forum and I will be back a lot I am sure!!! Thanks a ton!!!
 
i thought mine was an air leak but it was the tors and idle set wrong. i dont know what the right setting is but it seems to be much better then it was.