50cc Motobravo stalls when cold By inca32 (Read 2,585 times)

[inca32]

Just bought a 2008 Motobravo 50cc scooter with 42 miles from a private owner. Runs great when warmed up but is difficult to keep running until then. Have to keep playing with the throttle for 2 to 3 minutes and run it at 20 to25 miles an hour. Being new to these little engines I could use a little advice on how to trouble shoot.

[Alleyoop]

Does the Carb have a Enricher(auto CHOKE)? If so it may not be working. Can you take a picture of your Carb that would help determine what may be wrong.
Alleyoop
Here is what it would look like If your Carb has one:
RIGHT SIDE OF CARB:


LEFT SIDE OF CARB:

[inca32]

It is the one with the enricher on the left side.

[Bashan]

Here is a link to Alley's enricher video. You can test it by hooking it up to a 12v DC battery and wait a few moments for the plunger to come out about 3/16". If it doesn't you need a new enricher, it's not getting power in the carb, or the seal at it's base is bad. Check the plunger first. Rich.

[inca32]

I understand that the enricher stops the extra fuel when it warms up why does it run normal for 10 seconds then stall and run rough for 2or 3 minutes? The enricher would not stop the extra fuel for 2 to 3 minutes, what is happening in the mean time?

[sprocket]

You might have a partly plugged jet...

[Alleyoop]

Ok, try this and it will tell you if your Pilot Jet is Clogged or not and if NOT then your carb needs adjusting for cold starts WHICH is what I think your problem is.
Alleyoop

Before you start it COLD, Turn the Fuel Ratio Screw Clockwise until it stops and then counter Clockwise 2 turns and see if that helps. Then after it warms up 4-5 minutes adjust it so you get the Highest Idle:

1. Turn it Counter Clockwise 1/4 and wait 10-15 seconds to allow the engine catch up with the new setting.

A. If the Idle Goes up, Repeat #1.
B. If the Idle Goes Down or doesn't change Turn the Screw Clockwise 1/8 back and go to #3.

**** IF ON THE FIRST 1/4 TURN on #1 THE IDLE GOES DOWN OR DOES NOTHING TURN IT CLOCKWISE 1/4 AND GO TO #2***

2. Turn it Clockwise 1/4 and wait 10-15 seconds to allow the engine catch up with the new setting.

A. If the Idle Goes up, Repeat #2.
B. If the Idle Goes Down or doesn't change Turn the Screw COUNTER CLOCKWISE 1/8 back and go to #3.

3. Now you can adjust the IDLE SPEED SCREW the one with the SPRING ON IT to lower your idle so that the REAR WHEEL JUST WANTS TO TURN.

**** IF #1 and #2 DOES NOT CHANGE YOUR IDLE YOU HAVE A CLOGGED JET AND OR PASSAGE WAY **** You will need to clean out the JETs and PASSAGES.
Alleyoop

[inca32]

Thanks for the help! I will give it a try.

[Alleyoop]

So what is the verdict it only takes five minutes to do this.
Alleyoop

[inca32]

Seems like it is much better but I am not sure if it was stone cold when I made the adjustments. I will let you know in the morning.

[sprocket]

You need to make that air/fuel adjustment on a hot engine...not a cold engine...Run it for 3-4 minutes and then adjust

[inca32]

Made the adjustments yesterday and reset the idle. Ran fine yesterday and this morning, drove it this evening and it won't idle so tried turning up a bit but it wold need a a out a quarter inch to keep it running. What do you think?

[sprocket]

Hey whatever works...