Jonway YY250T scooter spitting and sputtering By rcapete007 (Read 1,497 times)

[rcapete007]

I have a 2011 Jonway YY250T scooter with a CF250 engine. It has a 30mm carburetor with electric choke with extra wire for the temperature sensor. When I start the bike cold, it runs fairly well for about 2 to 3 miles then starts to bog down (spitting and sputtering) and continues to do this unless I turn the scooter off and let it sit for at least 2 minutes, then restart and it runs like a bear until it gets turned off and sits for a while again. I have tried 2 other carburetors and other electric chokes and it continues to do the same thing. I also have changed the CDI and still the same thing. Any help with this would be appreciated.

[Alleyoop]

Try adjusting the carb, You can try closing the fuel ratio screw CLOCKWISE then turn it out 2 1/2 turns COUNTER CLOCKWISE. It appears it needs more fuel, it starts and runs good at first cold because the ENRICHER is feeding it extra fuel then when it shuts off the extra fuel you appear to have the problem.
Alleyoop

scooterdoc.proboards.com/thread/1499/4ts-carb-tuning

[Guitarman]

Sounds like a clogged carb. But since you tried 2 others, I'd start looking at my fuel pump and lines. Check the gas tank for debris.

[rcapete007]

I also noticed on my gauge for RPM that when this starts to happen the RPM gauge drops to 0 and stays there for some time before it kicks back in and then goes to 1000 or more but it still spits and sputters but i don't understand why the RPM drops to 0 and stays there.

[rcapete007]

Fuel pump was changed just recently and fuel filter is clean. I have had this problem since I got the scooter 2 years ago but about 3 months ago I was riding it and it popped and then was hard starting and pouring gas out the overflow tube. I corrected that by adjusting the float and cleaning the needle and seat. It continued to spit and sputter after the carb was fixed (back to the way it was from when I got it) I have tried many things but continue to have the same problem I'm thinking it's more electronic like possibly the coil or the CDI although I have changed the CDI with the same results.

[Bashan]

Have you adjusted the valves?

[Alleyoop]

Also let me ask this, WHERE in the THROTTLE RANGE does the sputtering happen at WOT at any throttle position etc..

[rcapete007]

It seems like it happens at WOT or at least thats when I notice it. I'm generally going about 45 to 50 miles an hour when I notice the Tach RPM's drop to 0.

[rcapete007]

Although once it starts to happen it spits and sputters at any throttle position

[Alleyoop]

Well I got to tell you if it only goes 45-50 at WOT something is not right. That 250 should be doing at least 60+mph at WOT. So is it that your gaining speed and it happens around 45-50mph? Also is the TACH dropping to zero but the motor is NOT, because if the tach is zero and it is also the motor dropping the rpms to zero the motor would be dead.

[Guitarman]

My 250 (244 actually) does almost 70 WOT. You are having some serious problems if you only get 45-50.

Sent via my Android.

[cyborg]

I smell an intermittent electrical problem,,, tach drops out goes to zero then comes back on,,, coil bad?

[Guitarman]

Short in the wiring? Bad CDI? I would;

1. Adjust the valves.
2. Replace the plug.
3. Adjust the carb.
4. Check the airflow. Make sure it's not blocked or something.
5. Check the plug wire and coil.
6. Oil change in both engine and gearbox.

Those seem to be the most common fixes for this kind of problem, and even if it's not one of these, it never hurts to do the maintenance. (Not all of these will cause that but they are all common issues with these bikes and should be looked at anyway.)