2011 Kingring 50cc JL40QT-4 RPM troubles
 

Aloha,
Im having abit of trouble with my moped, bought it used though
i did some upgrades in hopes to make it go Faster, purchased a Performance Orange CDI , Performance Variator and some Sliders 4g and 6g, a Prejetted 18mm Carb, and a 1.5k spring and a Orange Performance Coil from Scrappydogscooters.com ( Awesome folks there )

Now my problem lack of power even with out the upgrades, i'll explain, my scooter has the 139qmb engine make by jinlun on the side of the cover, the Bike Revs up alittle slow but Tops out at 4.1k RPM at best, Now Changing out the CDI with the performance one with the unlimted Rev, it Still is at 4.1k rpm, i have the 4g weights in for top RPM testing. but for the life of me i cant pull out any more power in this bike at all, ive Placed in the carb and a New inline filter as the old one was bad new belt because the old one was definaly bad. All my parts come from Excellent sources ( Aka Carb variators

The bike looks like one of these http://www.scooterdepot.us/50cc-4-st...tml#pro_tabs-6

But its made by kingring but thats an exact copy of it down to its looks, Love that its a large frame and 12" tires ect, But it really lacks in the performance department here even with performance stuff on. Does anyone Have any Suggestions or have experience with kingring mopeds ( i cant even access the kingringmotors.com website its down ). Dont know what else to think of, i have friends with mopeds all running the same engines as this one and Stock all Rev much higher and accellerate quicker.

The bike itself runs ok it takes time to get to top speed just around 20-27 at best. So im alittle bit at a confusion here.

First thing since it is used test the compression on the motor. If the compression is low it will loose a lot of power especially with a load on it. Then you can check the Valves adjust them BOTH to .003 inchs.
Lefty

Yep those were off definatly as when i bought it said it had cam work done.. definatly off. now set to .003, so its abit more peppier definatly

But unfortinatly im still hitting that 4000 rpm mark and cant go any higher
then that on this 4 stroke, and i dont think its the cdi or the coil cause their both the orange performance ones from scrappy dogs :). so im wondering what else could cause it.. on a top note original and orange cdi both do the same thing on my bike, i know the performance one is better and has no rev limit but still... confused here. But Thanks for the Valve tip there Lefty that makes a diffrence definatly jusdt need to figure out the rest.

Well that is good that you adjusted the valves but if it is still not getting over 4K only a few things will cause that.
1. Low Compression
2. Something wrong with the Variator
3. Bad CDI

And that is if when you do reach 4K the motor is not backfiring or sputtering or bogging or making sounds.

Let me ask when you crank it up full throttle does the motor make any sounds, BRAT, POP, BACKFIRES?
Or does it just wind up to 4k and runs good at 4K?
Lefty

when it hits up to 4k it seems to run fine, course the carb noise is alittle hollow, ive been doing adjustments on the fuel mixture, but regardless of that, no sputtering backfiring, the bogging comming from the carb possibly i might toss my stock carb in for a test on that tomarrow but even then that carb couldnt do over 4k either, even when left on the stand and reved the engine and let the wheel spin the Tachometer stays at 4k. and this is with both Stock and the performance CDI i recently purchased.

Take the CVT cover off and put it on the stand and start it up and see rev it up and watch the belt on the Variator. See if it climbs to near the edge of the Variator.

If you hear a BOGGGGGGG sound holding the throttle wide open then it is bogging.
Make sure about the sound makes a big difference. If it is bogging then your getting to much AIR do you have a UNI or some free flow filter on the carb?
Lefty

i made a quick Video here http://youtu.be/mDFNvV-3kWM
So there it is, it should sound ok my Samsung Note 2 has a fairly
good camera and thats it.

Also like i mentioned there was cam work done on it, and i HAD to redo it
i set it for .003 on both sides, Do you have a recommendation for intake and exaust
rather then both being set at .003? i was thinking intake .002 and .005 exaust?

It sounds good, as for the valves sure you can try .002 on the Intake and .005 on the exhaust. Some folks set the exhaust to .005 so that it lasts a little longer before the next valve adjustment is needed. But IF it CLATTERS then bring it down you do not want the rockers slapping coming off the lobe of the cam. Ticking valves are fine that tells you they are not tight and not to loose.

I saw that the belt climbed near the edge of the Variator so that seems fine. Did you say it has a #88 MAIN JET in there? That is to big of a main jet for just a uni on it. Usually an #88 is needed when you put in like a 72cc BIG BORE KIT.

Try this ride it and when you get to where it doesn't want to go anymore BACK OFF the throttle about 1/4 of an INCH and hold it there.
Now pay attention to what the scooter does.
A. Does it pick up a little speed
B. Does it just settle down
Lefty

i believe its your carb swap the carbs back also what size jets on the new carb did you clean and check the inside out before installing it

Are you running that Uni dry ? It needs to be oiled or it be too lean . Sometimes with the stiffer clutch springs you need heavier weights to push out the belt .

It looked like the RPMs got faster after the tach stopped at 4K so it may be off .

Have you done a compression test ? Are you sure its a 49 as it may have a BBK if it has been worked on

Ya seems the tach something is wrong with it or stuck i really dont know...

the Uni filter is dry out of the box and placed on ive been modifying the fuel mixture seems good now ive got 6g sliders but my performance variator came with some standard 8g rollers i may try them..

it ldoesnt pick up speed it settles down mostly, im going to order some smaller gets im thinking and 80 and a 85 as i will prolly be placing my muffler on today as my stock one might have a restriction

That is what I expected it is running really rich with the #90 jet. If the scoot sped up when you backed off it would mean it is LEAN.
So put in a smaller Main jet.
Lefty