Jonway 300t By avibarathyy300t (Read 1,445 times)

[avibarathyy300t]

Hi, I have a 300 cc jonway master that starts fine. As soon as I have it at low rpm -2500 or so. It just dies after I leave the throttle. If I hold the throttle at steady rpm for a few seconds, it idles fine. Idles screw is fine Stripped and cleaned carb about a month ago. All pipes and are secure and in the right place.
Is there an easier way to adjust the air gas screw on the carb? It's in the most awkward place. How would I know if it's adjusted correctly?

[Alleyoop]

Here is how to adjust the carbs Fuel Ratio Mixture and you need something like this to get at the screw.
Alleyoop

www.scooterdoc.proboards.com/index.cgi?board=intake&action=display&thread=1499

[avibarathyy300t]

Thanks allot for the info. I finally got the tools and made the adjustment. The only way it idles and throttles the way it should is turning the screw full clockwise to lean. The issue now is that it struggles to start unless the enricher is fully engaged. I have to crank it a good few seconds before it takes. Also at low rpm it on load it shudders and stalls if I leave the throttle suddenly.
Strange.
Any other suggestions.

Thanks again.

[Alleyoop]

Did you put in a different carb or changed anything on the carb?

If it only wants to idle right when the Fuel Ratio Screw is completely closed it means the PILOT JET is to big or it is sucking gas from somewhere else. Also when you adjust the carb make sure you have the AIR FILTER connected otherwise the adjustments will be for not.
Alleyoop

[avibarathyy300t]

No. Nothing at all. The filter was connected while doing the adjustments. Where else could it suck gas from?
Do you think the valve gap may be an issue? Do perhaps have an adjustment procedure?

[mike6736]

I was just going to ask if you had set the valves. My 300 Magnum carb was hard to adjust if the valves were not right. I set mine at 4 on intake and exhaust

Magoo

[avibarathyy300t]

I'm actually busy with the adjustments now. Very difficult to get to them. I will post results after. Setting it .004 on intake and 006 on exhaust. Hope it works. This is allot of work. 😔
Thanks again guys.

[Alleyoop]

Good luck, yea on some it is a PITA, but after the first it gets easier and you will find ways to make the adjustments easier.
Alleyoop

[avibarathyy300t]

I adjusted the valves and it running better. Still stalls if I keep at low rpm on load. Feels a little smoother though. Not any easier to start up. Any other ideas?? Btw. The fuel gas screw is still all the way to lean. Still suspect something to do with the carb.

[Alleyoop]

Do you have a tach on the scoot, you may just need to raise the IDLE using the IDLE SPEED screw on the Throttle cable side. That also may help the starting problem to allow more air in. After it warms up it should idle around 1800-2000 rpms. The 250s do not like to idle low.
Alleyoop