I recently purchased a Qingqi 49cc 2-stroke motor scooter. The manual calls for the gearbox to be filled with “20# (HL-20) oil”, but I can’t find any SAE equivalent for this. Some searching indicates that most small scooter gearboxes are either filled with 70W-90 gear oil or regular 10W-30 engine oil–but there’s a big difference between the two and I don’t want to mess it up with the wrong type. Does anyone know which one corresponds to HL-20? Since the scooter is made in China, I’m guessing this is an Asian designation. The drivetrain incorporates a wet centrifugal clutch, if that makes any difference.
Nice find, astro. The photos in that second link show features which are visually identical to my engine, and it is a chain drive. The gearbox looks identical, as well.
A little more research convinced me that astro’s link is correct. There are a complete set of engine diagrams on that site, all of which correspond to those in my scooter’s manual. So, today I drained and changed the gearbox oil with Havoline 10W-40. Glad I did, too–the existing oil was looking pretty black and nasty. I suspect it wasn’t the best possible oil to begin with, since the scooter only has only a bit over 500 miles on it. Considering it’s only gear lube and isn’t exposed to high engine temps, it shouldn’t have looked the way it did! After refilling, I took it out for a test spin. The clutch is grabbing nicely–possibly even better than before, but that could just be my imagination–and everything appears to be running smoothly. I’ll probably do another premature oil change, just to flush out any of the remaining crappy original oil. Any other suggestions anyone has about this or 2-stroke engine maintenance in general will be greatly appreciated.
Thanks, astro!
Since Astro has answered your question, I’d like to add: A Qingqi. Sweet. I’ve (illegally) ridden my aunt’s in China. They’re nifty little bikes 
Get a 4-stroke! 
Seriously, 2-stroke engines are used on off road and trial bikes for various reasons (less weight, more power, reduced engine braking, etc.) but they are not really suited for street bikes.
Yeah, it’s not a bad little bike. Pretty peppy for a 49 cc engine–it gets up to 35 or 40 MPH in about 10-12 seconds on level ground. It annoyed me that the front panel didn’t have turn signal indicators–it’s all too easy to forget you have them on–so I installed a couple green LEDs. I also upgraded the headlight bulb from a 15/15 W (low/high beam) to a 35/35 W courtesy of the dealer, who gave me a free replacement when the original bulb’s high beam filament blew out a couple days after I bought it. They also upgraded the mirrors when I brought it back in because one of the originals was somewhat loose and kept vibrating out of alignment.
Question: how does one illegally ride a scooter? Is a license required in China? Here, in most states, a 49 cc scooter doesn’t require one–although restrictions vary somewhat from one state to another. For example, in most areas, you cannot ride one on an interstate highway–not that I’d WANT to.
Care to elaborate? I’ve had no problems with it, and for a 2-stroke, it’s very clean-running. There is very little (actually, surprisingly little) smoking once the engine has warmed up, and although somewhat noisy it’s still much quieter than many more powerful, overpriced bikes with excessively loud and inefficient motors (coughHarleyscough).