Roketa MC-16 50cc CANT KEEP IT RUNNING By mikey34 (Read 484 times)

[mikey34]

NOW, I can't even keep it running...

I took the PAIR system off, (at first I thought it was an exhaust leak, from all the noise it was making), SHORTENED the fuel delivery hose from the filter(I DID REPLACE THE FILTER, WITH A FILTER 4 TIMES THE SIZE... I DON'T THINK THAT MATTERS THOUGH...) I have tried BOTH needle positions RICH and LEAN, and it started on the middle position.

IN and OUT on the AIR/Fuel screw... the exhaust is tight, There may be a leak at the airbox, as some of the screw points are broke off, but I THINK it would at least stay running even with that leak...Right?

it will stay running IF I KEEP THE THROTTLE at 1/3 - 1/2... AS SOON AS I LET OFF, IT DIES DOWN, AND SOMETIMES WILL RECOVER, AND IDLE, BUT IF YOU GO 1/2 THROTTLE AND OFF A COUPLE TIMES, IT DIES, I DO NOT!!! GET IT GUYS, AND I'm pretty good at figuring this stuff out... I REALLY NEED HELP!!! lol

THANKS ALOT GUYS!!!!

[rob63]

I can`t help unfortunately but I`d be very interested if someone else has encountered this and found a solution.
I've had the same problem with a couple of 125`s on the fleet, both had been run very low on oil to the point that only a couple of drops had come out when the drain plug was removed. I tried adjusting the valves, checking compression, adjusting the carb, even replacing the carb with a brand new one. Eventually I replaced the engine on one and put the old engine aside for parts. The other scoot ran similar but was useable so I gave up and put it out for hire, so far no problems have been reported.
The only conclusion was that maybe either the cam chain had stretched or the crank had bent slightly or become unbalanced. I must admit that the bloody things almost had me tearing my hair out at times.

[mikey34]

Thanks alot Rob, I REALLY hate to hear that, because truth be told, it FEELS like a wobbly CAM, I know you can't really distingish that with out tearin it down and measuring the cam, or compare to another, BUT it FEELS like its "Unbalanced"... BUT NOW, that I can't even get it to stay running for more than a few revolutions with out keeping it 1/2 - WOT, I have another QMB139(on a personal scooter) that I will be transplanting MORE than likely, SINCE this is a customer's scooter, I will transplant my engine, charge him a few bucks for the labor, say 80 bucks or so, and rebuild his old engine, the engine only has 300 miles!!! on it, I HAVE NO IDEA, WHAT, he could have possibly done to it in the short time it has been rode. Maybe he didn't FINISH the assembly correctly??? I have yet to buy a BRAND NEW one haha, I can USUALLY get the second hand ones running JUST FINE....

[Guitarman]

Check the oil and the valve adjustments. Obvious, but its all I can think of.

[Alleyoop]

I assume it is a Gravity fed system and with a huge Fuel Filter it is most likely not enough suction to keep the filter filled. Put on a regular size filter also check your exhaust Valve it maybe tight and loosen compression. If loosing compression the motor will not hold low rpms and they die. You have to keep on the throttle to keep them running.
Alleyoop

Get a good filter and you can also clean them when you see them get black:
www.bikebandit.com/visu-filter-large-capacity-in-line-fuel-filter

[straightbangin]

I'd go with changing fuel filter first since its the cheapest thing to try to fix it but when ive had this problem id add a new carb, fully charged battery and new spark plug seemed to do the trick (correct valve adjustment as well too) I get my carbs on ebay for around $30 and I have a 50cc, let me know if you want the link to them. Good luck. I know far too well how much scooter issues suck.