SUNL scooter, questionable condition

[BrianW]

A neighbor just gave me a 50cc SUNL scooter that was in his barn when he bought his property. It’s a 2006 model with 218 miles but has been in this barn for at least 8 years and who knows if it ran when parked there. No title, no key, no gas cap, etc. I’m wondering what my first steps should be, particularly how to bypass the ignition switch. Primarily, (if not blown up) I hope to teach my wife to ride on it and have it as a “farm bike”.

Engine has compression. Definitely going to drain tank and change oil/ spark plug. Any feedback is appreciated

[BrianW]

A photo for reference, I believe it is the basic gy6 engine

[humanbeing]

Typical color code: http://chinariders.net/showpost.php?p=229783&postcount=11
Typical 50cc GY6
https://i.postimg.cc/CZLMknzQ/GY6-50.gif (https://postimg.cc/CZLMknzQ)
Divides electrics into different groups is easier for layman's mind.
Good old 125cc Kymco GY6 (ie. the real deal) in above format
https://i.postimg.cc/sBwXN9kz/gy6-125.gif (https://postimg.cc/sBwXN9kz)

[BrianW]

Thanks Humanbeing, that is a very helpful schematic. Following it, it looks as though everything electrical on this bike is satisfactory so far.

Since I’ve not much experience with the gy6, I’m not sure what this black cylinder is for. This cylinder and the throttle handle/cable seem to be the only disconnected pieces at this point.

[tortoise]

not sure what this black cylinder is for
https://www.youtube.com/watch?v=ubUosWJUhM4

how to bypass the ignition switch
Remove kill switch pin (https://www.mopedarmy.com/w/images/4/4a/6pinout.jpg) from CDI connector.

[wheelbender6]

Farm bike is a good use for it. The engines were pretty good but electric problems were common.

[BrianW]

So I got the scooter to fire up. It idles surprisingly well and will rev up if done very slowly and carefully but will then die and is difficult to start. Cleaned the jets, bowl, float, changed oil and spark plug. Not sure what else to do next.

The vacuum systems on these are interesting- I have a lot to learn about them still. Also, unfamiliar with the concept of an electronic choke.

[tortoise]

Not sure what else to do next.
https://www.youtube.com/watch?v=gtiWCVa3Nss

Cut a strip from the side of an aluminum beverage can for a feeler gauge.

[BrianW]

https://www.youtube.com/watch?v=gtiWCVa3Nss

Cut a strip from the side of an aluminum beverage can for a feeler gauge.

But I’ve been drinking bottles all day!

Thanks for the video- good suggestion!

[humanbeing]

Cut a strip from the side of an aluminum beverage can for a feeler gauge.

That trick is good enough for GY6 125/150 :tup: BUT 50cc needs narrower 0.05mm/ ~0.002" clearence.

[BrianW]

Adjusted the valves and they certainly needed it. Top was at .007 and bottom was too tight to measure. Bike still runs rough and behaves pretty much the same. Will idle but does when revved and then is hard to start. Wondering if my effort to clean the carb wasn’t good enough, as it was my first time ever actually cleaning a carb and not just replacing it.

[tortoise]

Wondering if my effort to clean the carb wasn’t good enough.
Guidelines (http://49ccscoot.proboards.com/thread/16656/new-tool-jet-cleaning-reaming?page=1&scrollTo=311124)

[BrianW]

Put a new carb on today and the bike idles and revs perfectly now. A new throttle cable, throttle tube, keyed ignition/gas cap/seat lock and everythingis coming together nicely. Need to charge the battery, sort out the electric start wiring, and fix-a-flat the back tire and it will be ready for a quick riding lesson with my wife.

This thing was certainly ridden hard and put away wet for a very long time and still wants to run. These little motors are tough. Thanks again everybody!

[BrianW]

Alright, so not smooth sailing yet. First issue is that when the rear brake applied, there is a noise that comes from the rear of the engine that sounds like the noise you get when you try to turn the bike over with elec start when it’s already running. I don’t know if this is related to the stock brake system or if it has been tampered with in the past. Second issue is that after getting the rear tire to re-seat on the rim, the whole this is lopsided and bouncy when spinning on the center stand. Maybe a bent rim but I’m fearful that the rear drive shaft may be bent.

[cbrfxr67]

cool reading your progres!

[BrianW]

Final update and good news: the bike is now running great and has been good to us while I’ve been teaching my wife how to ride. The issues I described above were easily rectified once I finally had the time to dig back into it. The rear end noise was exactly what I thought, the starter was engaging because for some reason it has been wired to the rear brake light and has a toggle switch where the original starter button would have been.

The rear axle was not bent, I just had to tighten up the rear axle bolt which had come loose and was barely hanging on.

Alls well that ends well. Thanks again for your advice. See you agaon in the dual sport section 🤙