The problem with the original carb was definitely running lean. I'm wondering if the main jet was clogged. I should have cleaned it more thoroughly the first time.
My replacement carb came. A crappy $20 one from Amazon. I popped it in and the throttle response was great. No more power issues. But the carb immediately flooded and the scoot died after 30 or 45 seconds idling. I tried dialing it in and changing the float level but it just kept flooding on me. So I finally said "screw it" went to my local scoot shop and bought a Keihin and everything is fine now. Learned a lot over the last week. Thanks for all your help guys.
Lessons learned: you get what you pay for ($20 Amazon carb), and if you are going to a job (cleaning the first carb I had in there) take your time and do it right the first time.
Thanks for the input guys. I think previous owners didn't know much about engines. Everything seems to be stock. I have a new carb on the way, going to give that a try. I took the air filter off and it made the problem worse so I feel like it could be running lean. I sucked on the petcock vacuum today as well and fuel came pouring out of the line just fine. The carb is a piece of junk with no adjustment screw so I am hoping getting a decent one might fox my issue. Will update once new carb is on.
Hi all! Just bought my first scoot (Jonway 50cc YY50QT-6) a couple days ago and it came with an unexpected problem. Everything is fine from 0-60% throttle or so, I can get up to 30mph on flat ground. If I open it to full throttle, the engine loses power and if I hold full throttle long enough it dies.
I am really new to troubleshooting engines and am still earning, so please forgive my beginner lingo and questions.
1) Replaced the spark plug. The old one was a rich rust brown color around the top. I can post a picture if you'd like.
2) Opened up the carb. Cleaned it out a bit. It was in pretty good shape, but I cleaned the jets and float pin just to make sure.
3) Replaced the in line fuel filter, just to be sure.
My carburetor only has an idle screw, no adjustment screw. I'm wondering if it's running rich or lean but since I can't adjust it I'm wondering how that could be the issue (except for an air leak or gas delivery problem.)
Should I get a new carburetor for $20 or $30 with an adjustment screw? I ordered one on Amazon for the heck of it. If the adjustment screw came plugged by the manufacturer I can't imagine it's a good carb to begin with.
Any tips on what I could check next? I've had suggestions to check for an air leak, but I don't know how to do that exactly.
Thanks for all your help. I'm ready and willing to learn, just at a loss for what direction to take in my troubleshooting steps right now. Ready and willing to take pictures of any part of the bike or video of any of its behavior too.
Hey everyone! Just wanted to pop in and say hi. Just bought my first scooter a couple days ago here in Kona. It's a Jonway YY50QT-6 which has a 139QMB 4 Stroke engine in it. Looking forward to getting her running well and finally having some wheels to get around my island home. Thanks for letting me join!