Idling and stalling question: By richardthescooter2 (Read 1,976 times)

[richardthescooter2]

I have a mc-54-250b, just worked and cvt, cleaned clutch and pulley, clean varaitor (and of course geared both) back on the road again but now I have a low idle and coming up a hill out of town it stall. What is going on

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[Alleyoop]

After it is warmed up you should raise the Idle to 1800-2000 the 250s like to idle little high.
When you say stalled out going up a hill did it just quit on you or started to sputter then quit?
Alleyoop

[richardthescooter2]

Alleyoop, my scooter started jerk and stalled, I did notice my fan coming on more , but it is almost 70 here. now when I did that work on cvt I had my air box hanging there, if a hose came off would the scoot act like that?

[Alleyoop]

Yes if you had some hoses disconnected it would suck in to much air and it would cause the idle to start bounceing up and down TO LEAN.
Alleyoop

[richardthescooter2]

Thanks Alleyoop, I'll check it out, today as soon as I got scoot together I had to go to work. I before this job my idle was running good.

[richardthescooter2]

Alleyoop, Update on scoot, adjusted idle and tighten clamp on intake, going home last night scoot ran good

[Alleyoop]

Fantastic!! good job Richard, just a little TLC and minor adjustment.
Alleyoop

[richardthescooter2]

Coming to work today my scoot start again jerking like it want to stall, it seems that when the fan is on is when this is happening, could it be a bad coil wire? going home last night was cool out, ran good today stating again.

[Alleyoop]

WHAT!! Richard, when does it start to act up AND WHEN YOU SAY JERK, is it the MOTOR you hear changeing rpms or the actual speed jerking. Is that Fuel Ratio Screw sort of losey gooesy because with if it is not holding the setting it will vibrate and can turn either way which would make it run Lean or Rich. Some Fuel Ratio screws on some scoots have actually fell out due to the vibrations.

But lets first find which it is MOTOR LOOSEING RPMS GOING UP AND DOWN or the REAR WHEEL LOOSEING ROTATION which would point to something the CVT, Belt Slipping, CLutch Slipping Weights getting stuck etc..

So If you could explain in detail what is happening when you say it JERKS that would point to where the problem may be.
Alleyoop

[kz1000st]

Have you checked the valves lately?

[bcgreatness]

its interesting how he mentions that the scooter begins to shake and jerk only whilst the fan is running. i ponder if a wire shorting out could cause the scoot to jerk and shake? for a test could you put your scoot on its center stand, and start the motor and let it idle for a long time. i would allow it to idle long enough to where the fan kicks in, when the fan kicks in, take note of the change in engine performance and sounds, also after taking a good note, then while the fan is running, give it gas. while you are giving it throttle, raise throttle to 3k and take note, then raise it to 4k and take note, and do that untill you almost red line and bring back results. i know it wont be very accurate because there is no load on the scooter due to it being on the center stand but this is just to get a first diagnosis.

[richardthescooter2]

When this happens its more like inter-minted like it want to shut off and sometimes it does shut off and I have too pull over and crank it several time before it start The rpms stay the same, it just starts bucking and then shuts off like I turned the key off. I'm thinking it my be a bad ignition coil, it seems when my scoot getting hot and the fan kicks on is when I have the trouble, just seviced my clutch and varaitor, it seems to be working good ;D

kz1000st, just completed a valve adjustment about 500 mile ago.

[richardthescooter2]

bcgreatness, I have notice when the fan kick on there is drain on my lights just for a moment, then it seems good.

[Alleyoop]

I wonder, is yours a DC CDI? Because if it happens when the fan kicks on which is getting 12v from the battery and the lights are on that would Limit the Juice going to the CDI from the battery IF IT IS DC , which to me sounds like it. If that is the case then that would not have enough juice for the CDI to send to the COIL to fire the PLUG.
CHECK to see if there is a WIRE going from the BATTERY TO THE CDI. And maybe a picture of the CDI would also help.
Alleyoop

[richardthescooter2]

Alleyoop, I think it is DC, one side has three wires the other side has two, I'll take a picture and post it.