Question someone I know can answer...Throttle up from idle question

[Manns50]

Have an 81 atc200 have recently rebuilt carb and mixture screw is set per the initial adjustment after rebuild (have not hooked up a tach yet).
My question is it has been running fine for the past week....last night I took it for a short run down the road ran great. Come out this morning and it started up fine and made it halfway across the yard then died. it will start up but will only idle. When I try and throttle up in neutral it dies even when trying to throttle up slow. I choked it halfway to see if it was starving for gas and it acts the same. I adjusted mixture screw a little both ways with no luck.Dirt in carb maybe? It was cool last night and still is this morn could temp be causing problems?
Any help greatly appreciated.

[Dirtcrasher]

If it ran fine for a week, look to the obvious. Gas flow or a fouled plug........

[Manns50]

Ok would a fouled plug act like that? Runs fine at idle and starts easy.

[Dirtcrasher]

Man, when I had pingers, I ALWAYS had 4-8 plugs kickin around. I didn't even know what "jetting" was when I was 16,

[Manns50]

It was a brand new plug...pulled it last night flooded it I think so I pulled it to sand it and clean it up and it helped. I'll pull the new filter back off make sure it's not clogged and replace the plug see what happens

[RIDE-RED 250r]

Sounds like a dirty carb to me. Might want to open it up and investigate. You may have some debris in your fuel tank making its way into the carb.

[Manns50]

Ya kinda what I was thinking but not looking forward to taking the carb apart again. Just rebuilt it and cleaned it thoroughly has been running fine but I did just install an original air cleaner cage and filter with the box. It was rusty and I ran thinner thru it and blew it out as best as I could but it still could have let something be sucked up in there. I knew better than to put that on there like that....looking back I could kick myself! Should I replace any of the gaskets in the carb or just reuse them since its a recent rebuild?

[Manns50]

Just removed and drained the tank poured new gas in it blew thru the new fuel filter making sure it was clear and a new plug....made no difference. Guess I'll go remove the carb...ugh!!

[RIDE-RED 250r]

The gaskets should be fine, especially since they are new. It only takes 1 teeny tiny little piece of crud to get into the pilot jet or idle fuel circuit to cause problems.

[Manns50]

Well got it cleaned out but lost the little o-ring seat for the idle mixture screw. Have some o rings but not sure of the size....so have to buy another kit I guess. Didnt save the old one.

[RIDE-RED 250r]

Did you find any crud in there? How bout the pilot jet? Its got a tiny little hole in it that is very easily obstructed.....

[Dirtcrasher]

Yeah, that o-ring is important.......

[Husky250]

If it idles and dies when trying to add throttle that would be the Main jet wouldn't it? The pilot controls the idle and it's idling fine.

[RIDE-RED 250r]

No, pilot is from off-idle to 1/4 throttle. 1/4 to 3/4 is main circuit regulated by the slide needle. 3/4 to WOT in main jet. Dead idle is just a simple fuel circuit with an adjustable air inlet (idle air screw).


Idling good and dying as soon as you try to apply throttle is classic pilot jet obstruction. One of my 230 quads did this out of the blue last fall. I treat my ethanol blended garbage fuel im forced to use here in NY. Opened the carb,found it very clean. But somehow some little grain of sediment got into the pilot jet. Blew that out of there and the machine ran perfect. Its not always a generally dirty or fouled carb, sometimes you can get that small random little piece of sediment or crap in there that just gets into the wrong place.

[Manns50]

Ya I found a a piece of small sediment in the bowl so I know if there is one could have been another. Pulled the jets and sprayed everything out with carb cleaner and blowed it all out. Picked up another carb kit today for that o-ring. Question.....before I assembled with the o-ring first then a small washer then screwed the pilot screw in...thats how it showed it looked like to me in the manual but it just has a diagram of the parts removed as how they re-assemble. Could have misread it as the little washer was difficult to get out of the pi;ot screw hole causing me to lose the o-ring under it. Is that coreect?