125m starts but runs wide open HELP!!!

[42F67N]

I just got a 1984 125m today i traded a pocketbike for it,heres the problem the bike starts right up first try but revs to the moon when started the throttle isnt stuck,any ideas of what the problem could be?

Bike sat for a year without being started and i added gas and gave it 3 pulls and it fired right up but reved so high i thought she was gonna blow up.


Its in pretty good shape the tank dosent have a spot of rust in it and its never been treated only real problems with it are its missing a headlight the rear tire has a slow leak and the sub trans is busted

heres a few pics of it
http://img.photobucket.com/albums/v232/42F67N/125m003.jpg
http://img.photobucket.com/albums/v232/42F67N/125m002.jpg
http://img.photobucket.com/albums/v232/42F67N/125m001.jpg

[Oldshell4481]

did you check the idle?

[42F67N]

I havent really messed with it yet just added some gas and wanted to see if it started,the bike starts normal but then the rpms start climbing up i was wondering if maybe the carb being dirty could do it?

[Oldshell4481]

maybe, if something is stuck in there, wouldnt hurt to clean it anyway.

[Oldshell4481]

nice score on the trike by the way

[Wickedfinger]

Throttle slide might be in backwards .... been there, done that. Otherwise - a really bad intake leak.

[Dave223]

hey, same thing happened to me once to, the throttle slide is in backwards, heres the fix: unscrew the cap on top the carb, where the throttle cable goes in. Pull out the slide and the needle. Now on the slide are 2 grooves, a wide short one and a narrow long one. The wide short side goes on the same side as the idle set screw. or, to make a long story short, pull the slide an turn it 180, put it back in. :p

[42F67N]

Thanks guys

[42F67N]

Well tonight i messed around a lil bit with the bike and cant get it to stop reving to the moon :( i tried taking the slide out and spinning it, i tried adjusting the carb nothing seems to help no matter were i adjust the screws on the side of the carb it revs to the moon,its very weird because no matter how i adjust both screws the bike starts right up one pull.

any other ideas or input would be apprciated thanks.

could all the wiring where the headlight be have something to do with it,theres a few wires that arent connected to anything and the key is by passed

[83185s]

when * put the slide in did it go al the way down or stay just a little over the top of the carb?? if its a little over the top then its still wrong..it should slide in and go down quite a bit

[350x'inNY]

Hey... thanks for the pic! Now I know what that dash I have came off from! You need one of those HONDA dash pads? I might have one here.... I know I got a 84 125M headlight and shell.... let me know if you are needing one. If you take some good pics of the carb, I might have that here too. I basically got a complete parts 125M here except plastics, wheels, subtranney.

Did you observe the operation of the slider? Did you have the air filter and hose to the air box connected to the carb when you are starting it??? We (theolderfox and I) were trouble shooting my 225DX, and started it with the carb not attached to the airbox and it reved up to high heavens... regulated the rush of air a bit by covering the carb intake over partially with a hand and it reved back down some..... make sure thae air box, air filter and such are a go before mesing with carb adjustments...

[MTS]

Air Leak :)

[faf_racing]

throttle cable?? its been sittin for a year, maybe has some rust or dirt keeping the cable from moving freely. if the slide is in correct and intake tube isnt cracked. spray pb blaster down the cable and work it too seeif that helps. (motor off) of course! makes sense too me good luck! also see if the cable isn't creased or pinched somewhere causing the slide not too "slide" all the way down

[ktm1974]

same thing happened when i got my 84 125m, i tried everything. in the end it turned out to be a very slightly bent needle

[42F67N]

Thanks for the ideas i got somemore trouble shooting to do today :)

[Huffa]

If it's not too much trouble just take the air box off and observe thru the back of the carb throat (if you can) what the slide is doing while operating the throttle.

If operation checks out A-OK, start it up and spray D-40 all around intake area and head gasket area, the second the liquid seals the leak (if there is one) the engine should go back down to idle for just a second or two, then back up.

You may very well have a cracked dry rotted intake boot which is between the carb and motor or it's just not tightened or the gaskets are bad.

[jenndnn3]

It could be: (alot of folks mentioned these I just added a few)

Air leak: Spray starter around carb and intakes, fulley enclosed air box? put the lid back on. Jets clogged.

Slide piston sticking: causes bad throttle line, in backwards. Bent neddle?

Main jet open: open or sitting at bottom of bowl.

Air screw missing? I hope thats right name, its the one you dont seat, and only turn 1, 1/2 turns out.

These are the only ones I can think off off top of head.

[42F67N]

got it running like a champ :) turns out it was the screw that goes into the slide it was bent the guy before me must have installed the slide wrong and tryed to jam it down in bending the screw with the screw bent the slide wasent going all the way down in, once i took the screw out and got it straight the idle was perfect :) thanks for all the input and help guys :)