Idle proplems

[abansb]

I am new to scooter repair and want to do this myself

I have a 139QMB engine I am trying to get running I placed this engine on my scoot and it did start up but ran for about 2 minutes and quit I read a post here about it maybe the carb but I used my carb from my other engine that ran ok so I know that's not the prob

I also read somewhere else that it could be the valve sticking or needs to be adjusted I went out and got some filler gauges and I adjusted them to .003 on both the Intake and exhaust after I put it back together I seen in the manual that the intake is .006 and exhaust is .003 I am not for sure if this will make a difference or not I am thinking of readjusting it.

Also I am not sure which is the exhaust and Intake the top or bottom ?

I really like to get this engine going due to my other engine I am currently running it has a few problems as is oil leaks and exhaust bolts are gone broke off and reamed I really don't know how much longer this engine will last I hopefully I can get this other one going so I can use it till I can get the one I am running now fixed

Any help would be gratefully appreciated

Thank you
Tom

[speedy1125]

top is intake (carb on top) bottom is exhaust (exhaust pipe on bottom)

is gas getting to the carb? sounds like it ran long enough to run the gas out of the float bowl then quit. is your fuel valve working? its the thing that the gas line goes to from the tank and also vacuum from the manifold (manifold vacuum opens the valve when running). some bikes have the fuel valve directly on the bottom of the tank, some are on the frame rail.
is that .003mm? that should be fine.

[abansb]

Thank you for the reply Speedy

Yes that is .003mm

yes gas is getting to the carb I use the carb on my other engine that is currently on the scoot starts and runs fine on that engine

[speedy1125]

what is this motors history?

[abansb]

I am really not for sure it was an extra motor with my scooter when I bought it the person said it was once on the scooter they replaced it with one that is on it now

[speedy1125]

that doesnt sound good. it time for a spark check and i would do a compression check too. that motor was replaced for a reason. 49ccscoot.proboards.com/index.cgi?board=basicstuff&action=display&thread=647

[abansb]

Thanks Stroker95 I am going to check this engine over

Thanks again everyone for the help

Tom

[Fox]

.002-.003 in is the setting for both valves.

Have you tried adjusting the idle mixture screw?

[abansb]

ok I have them set at .003

I did when I had it on the scooter

[abansb]

OK here is what I have done I have set the valves to .003mm I couldn't get the filler gauge between them I also checked the timing and reset it.

I desided to throw it on the scoot and try praying it would start and stay running kind of hard to do by yourself with no shop or anything..

Got everything bolted and wires hooked up kicked it fired right up I reved it a few times kind of scared me lol really couldn't believe it was really running that long used to run for about 2 mins and stop.

A few problems I have run in to :

I placed the belt on and put the cover back on and reved it to tighten the belt but nothing still wont pull and the belt is still loose?

while trying to get the belt on the it died I kicked it back the only way it will stay running is if I hold it wide open what would cause this ?


Thanks again for all your help I couldn't have got the engine running this close if it wasn't for 49ccScoot.com and members here

Tom

[speedy1125]

assuming the rollers in the varaitor are in the right place, sounds like you have the wrong size belt. should be a 669-18-30 on that motor.
Describe how you set the timing. do you mean mechanical timing or ignition?

[abansb]

I set the timing mechanical

[speedy1125]

many times on chinese 139qmb engines, the true tdc mark is the 'T' itself and not the line beside it. if you have to hold the throttle all the way open for it to run then it sounds like the mechanical timing is a tooth off.

[abansb]

ok thanks Stroker95 I will try that I set it by the line

[abansb]

ok that is the size of the belt I put on 669-18-30 for some reason the clutch is not engaging now it is I don't know what happened there

Now to just get it running right