83 ATC 250R reving up at idle and without the plug wire !~!

[3wheelerlouie]

i just finished re-assembling the engine on my 83 250R and after firing it up and idling for a few seconds it started reving up without me touching the throttle , it just goes way high , i even removed the power wire from the module and the spark wire from the plug .. it did this a few times and i am just confused of whats going on. what would cause this?? i checked for leaks but everything seems okay, the funny thing is that when it started reving the second time i fired it up i removed the spark plug wire from the plug itself when it was reving and it just kept running. what will cause this ??? i was kinda freaked out thinking that the engine might blow up or something.. would having the wrong oil/gasoline mixture do that also???? what about exhaust leaks??

[MTS]

do you have the slide in the carb the right way? that or an air leak somewhere.

[Saul]

It's usually a sign of the bike NOT getting enough gas, same as if your riding and the 2-stroke starts to run out of gas - it will rev to the moon.

Have you gone through the carb? Checked the float to see if it's sticking, check your slide, check your idle, check all the jets, maybe the pilot is clogged - have you changed jets? Maybe they are too small?

I stuck a small 'slot style' main jet in my trike one day instead of a 'he head' main - the slot was WAY shorter then the hex head so the engine couldnt get gas (just enough to start) and it revved itself to the moon. Pulling the plug cap allowed me to kill the engine though.

It really sounds like a fuel starvation problem to me - but explore every avenue one step at a time until you figure it out.

Good luck and keep us updated.

[3wheelerlouie]

the only thing i did was move the clip on the needle from the verry bottom to the verry top because it was running FAT , i wonder if this will cause it.. yes i am an idiot when it comes to the 2 stroke engines..

[Saul]

the only thing i did was move the clip on the needle from the verry bottom to the verry top because it was running FAT , i wonder if this will cause it.. yes i am an idiot when it comes to the 2 stroke engines..

You don't ever move the clip from one extreme to the next - what you just did was adjusted the needkle from it's 'richest' position - meaning LOTS of gas going to engine all the way too it's 'leanest' position - meaning NOT MUCH gas going to your engine.

An adjustment that extreme, yes, may have caused this problem - but be thankfull you didn't get a chance to 'hop on and ride' because had you got out on that trike and started cranking on it you could have easily seized that engine or blew your piston to pieces from an extreme lean condition.

May I ask why you moved the clip from the bottom all the way to the top in one shot? In the future move the clip one notch at a time, test the trike and chnge another notch if needed.

And - only do one thing at a time.

[3wheelerlouie]

should i move it to 2nd fromt the top or second from the bottom ??? i am an idiot i know, but i have severe allergies right now and my brain is not functioning well..

[Saul]

should i move it to 2nd fromt the top or second from the bottom ??? i am an idiot i know, but i have severe allergies right now and my brain is not functioning well..

Your allergies will be the least of your problems if you try and keep running that trike in such a 'lean' state.

If the clip was on the very bottom position and you feel adjustment is needed then put the clip in the notch NEAREST the bottom notch, so second notch from the bottom. Then start your trike and see how it runs. If you feel further adjustment needs to be made - move it up one more notch.

One notch at a time. AND one part adjustment at a time.

example : don't adjust your needle clip setting, tinker with your air/fuel screw, change plug gap then start the Trike up - cause if something is worst OR better you won't have a clue which adjustment made the 'change' - one thing at a time.

[The Goat]

Why did you change your carb settings? Mods or what?

[NINJA]

Your engine is dieseling or glowpluggin like an RC car engine. When the lean condition occurs, it is getting so hot in the combustion chamber that something in there is heating up till glowing like a lightbulb! If you have a clean combustion chamber with nothing sticking out there (piece of piston ring stuck in head) then it is actually your groundstrap on your sparkplug that is glowing. My guess would be that it is your flywheel side crankseal that is leaking. If your carb slide is in properly (pin lines up with slot and allows slide to bottom out in carb) then it could be your intake manifold leaking, check to see if you tightened clamp around carb. It could be the base to cylinder gasket not sealing, but not too likely. Hell, you could be sucking air from between the case halfs. That is usually spotted by the presence of oily residue at the case seams, same applies for the base and head gasket. What you really need to do is a leakdown test, but I know most people don't know how and don't bother. Lastly, the stock starting position for your needle is in the middle clip position. If it is revving up without you touching the throttle, then THE NEEDLE IS NOT WHAT IS CAUSING THE LEAN CONDITION. Running it with the needle lowered all the way will definitely cause a lean condition while riding it but it won't be until 1/4 throttle on up.

[daniel_250r]

its possesed

[atc500x]

Probably an air leak somewhere,readvalve,crankshaft seal,crankcase gasket.....perform a leak test but pluging exhaust and intake and apply vacuum

[3wheelerlouie]

UPDATE!!
after tinkering with the carb for a few hours i decided to install the carb out of my 82 R and it was like night and day. it started quicker and idled way smoother than the other carb did.. i think it had the wrong carb in it because its bigger than the one out of my 82.. the plug stopped fouling up and no more "glow plug" effect.. woohoo!!!! what carb should be in an 83/84??? this one is a Mikuni 38mm and its quite a bit bigger than the 82..

[NINJA]

Something is not adding up here.