Cuts out at 40 By johnjs (Read 672 times)

[johnjs]

My 139qma china made rolling piece of plastic has run good until a few days ago. i adjusted the valves twice...new fuel and air filter..spark plug,, It ran great always at 40 but the other the other day i hit 50 going down hill and thats when the trouble started. It drops down to 30 then runs good,i give it gas until 40 again and it cuts out again until around 30 again. Im so lost any ideas where to start looking? Thanks as always for the help.

[tvnacman]

When you changed the fuel filter did you move the line and create a low spot? When you changed the air filter did you put a different air filter add or remove any parts?

John

[johnjs]

all is the same as it was before.
i forgot to add it never hit 50 before until i adjusted the valves the first time.

[tvnacman]

It could be starving for fuel, now that the valves are adjusted. It could be overheating at wot too. Tight valves could mask a lean carb. How does the spark plug look?

[cyborg]

and to add did you adjust the valves correctly?

[johnjs]

ty guys ill pull the plug and see how it looks...i followed step by step when adjusting the valves so i hope i did it right cyborg.when i bought the new carb 2 months ago i just replaced and no adjustments were needed. So does adjusting the valves also mean tweek the carb also? I aslo looked at the belt cause i thought well hell went a little faster maybe its slipping or tore up but it look ok.
I just need it to last 3 more months until i get a another the wife said for my birthday lol. Thank you all so much for the help.

[Alleyoop]

Check the diaphgram it might have ripped it going down the hill to much pressure(HAHA) and it will not hold the needle out of the main jet all the way.
Alleyoop

[cyborg]

Alley may have a point here pull the carb top and check the diaphragm for tears or holes

[johnjs]

Pulled the plug and checked the diaphragm both looked good i was reading another reply on another post..i didnt pull up on the rocker when feeling with the gauge so i may have did it wrong Thanks all

[Alleyoop]

You do not have to pull up on the rockers to put the feeler gauge in. Here is what you do:
1. Loosen the lock nut.
2. Unscrew the adjuster out a couple of turns.
3. Slide the feeler gauge in between the Valve stem and Rocker.
4. Turn the Adjuster clockwise against the Feeler Gauge.
5. Move the feeler in and out and adjust the Adjuster so that you feel a little drag as you move the Feeler gauge in and out.
6. Hold the Adjuster with your hand or pliers and tighten the Lock nut.
7. Do this for both valves.

RE-CHECK YOUR GAPS BEFORE PUTTING THE VALVE COVER BACK ON YOU DON'T WANT TO BE DOING THIS OVER AND OVER:
A. NOW turn the motor over a couple times by hand NOT USING THE ELECTRIC START OR KICKSTARTER. Either get a wrench and turn the FLYWHEEL CLOCKWISE a couple of times or If the CVT cover is OF turn the VARIATOR COUNTER CLOCKWISE and AGAIN ALIGN the CAM SPROCKET and RE-CHECK the Valve gaps.

B. Whatever size feeler gauge you used to set them TRY TO SLIP IN THE NEXT LARGER SIZE, It SHOULD NOT SLIDE IN. Then try the size you originally used and it should slip right in. If so you are done and you can now put the valve cover back on.
Alleyoop

[cyborg]

what he said

[johnjs]

Ty ty...followed step by step and did the triple check....went for a quick ride all seems ok..tomorrow or the the next day is a beer run lol i will see how it acts then. May i say thank you all for your insight and help for us new guys that are getting use to the scooter life.

[johnjs]

Hmmmm still having the same problem grrrrr....maybe this will help solve my problem, it does not die but it sounds like it runs out of gas. When i restart it it is fine until it goes above 40 again then the same issue.any ideas please and thank you.

[kagetenshi]

My cy50-a did the same thing until I removed the fuel petcock and installed a manual cut off (Briggs and straton). Turned out my petcock was worn out. Its a cheap and simple trick, just make sure you cap the vacuum line that's connected to it if you decide to try it.

[johnjs]

Not enough vacuum at high rmps? at 40 its not wot its when i open up abit cause im not watching the speedo it happens ty ty for the input