85 250r hi rev and couldn't shut off......help!!!

[rouseanator]

So a little history got the bike in parts and put it all together started her up a few times and it would die after 1 min or so. then I started it and it seemed pretty good and it was like the throttle stuck and reved way up I tried to shut down with the kill switch and it wouldn't shut off, pulled the coil wire and it kept going for a little bit, then turned off the gas, then I hit the throttle and it died. It was pretty scary thought it was going to blow up. its around mid 30's to 40,s here in wa, mixed gas 20:1, no air filter(will order one) and the exhaust is zip tied up to the frame but on there pretty good main jet was 142 and stock exhaust, I have all fresh coolant and gear case oil, and no chain hooked up just was trying to see if the motor would run, like i said it was all in pieces. Please help with any suggestions......

[manbearpig]

Air leak.

Check:

intake boot gasket
reed cage gaskets
head gasket
base gasket
exhaust flange gasket & metal ring
stator side crank seal

[rouseanator]

So probably shouldn't start it anymore until I order air filter and exhaust gaskets, and bolts/hanger, but why wouldn't it shut off that was pretty scary, even when I pulled the coil wire off the spark plug. May be it was off but still turning over cause the high rev???

[Marty]

My atc 250r last year while being tuned on dyno did the same thing! I found mine was the throttle cable right where the throttle cap is at we noticed that cable was frayed thank god we spotted it there not at Glamis while I was riding.

[rouseanator]

Thanks Marty, I will check that throttle cable out.

[hatc200x1]

My 84 250r air hammer did the same thing, culprit was the stator side crank seal. Replaced it once and it still did it, leak down tested it again and air pissing out of the seal still, long story short she is at shop now so I don't have to deal with it.

[Marty]

And check the things manbearpig posted as well. Well the gaskets you can see, buy a can of carb cleaner and spray on reed gasket, head gasket, base gasket and if it revs you know where the leak is at.

[rouseanator]

I will have to check all of that out, got the shop manual so will read that up and figure it out. I have worked on a lot of atc's, totally taken apart and restored them but the motors never need much, so never rarely had to go into the engines, except to change a stator or 2. That's why I was after a 2 stroke cause I think they would be easier to learn on, and can hopefully maintain the motor myself also. Sounds like if it revs up its some type of gasket/air leak somewhere, the thing is it didn't do it every time most of the time it would run for a minute or 2 and then die before it ever really warmed up and smoke pretty bad(I have worked on a few 2 strokes and when they are not started in along time they always smoke I think, and then it gets better), and the last time it wouldn't shut off i thought it was running pretty well then hit the gas a few times and was trying to adjust the idle screw and it reved way up, so hope it easy fix just the cable of something stupid sticking. Kind of scared to start it again cause I don't want to blow it up.

[heusser85]

every time i have had that happen on two strokes i spray the engine down with carb clean while its revving and the carb clean kills it then i can locate right where the gasket is sucking air. engines don't like to run on carb clean it will not rev up with carb clean it will shut down.

[rouseanator]

204820
So I ordered a bunch of stuff, all the exhaust gaskets and bolts, uni air filter, and gaskets to the reeds, I am pretty sure that will be the fix because the 6 bolts holding the reed cage on we're not tight at all, also new throttle and clutch cable .

[rouseanator]

204888204889204890
Here is some more pics, the R idles good know but makes a constant chattering noise and smokes quite a bit. Also put on a new clutch cable on, and it pulls real easy and I don't think the clutch is working

[rouseanator]

https://www.facebook.com/video.php?v=1067623583265195
Here is a video of what it sounds like. Will start a new post on this Issue. Thank you everyone for the help!!!!

[Marty]

The rattle may be clutch. Nothing wrong with clutch rattle to find out if it is clutch pull lever in while bike is running and listen to see if chatter gets a bit quieter! Nothing major to worry about just make a note when you tear clutch open to check clutch basket for any severe wear, good luck

[rouseanator]

Thanks Marty, I hope that's all it is. Started a new thread called "85 250r clutch help please!!!"