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Discussion Starter #1
Hello!

My stock 49cc Cag, lose RPMs When i drive and it reaches approximately half Way Up in RPM, then i need to release the throttle and let the RPM fall down, or the motor stops. What can that be?

Sorry for a little bit bad english! :)

//Brooke
 

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French Fries N Cheese
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sounds like a carb tuning issue, or maybe an air leak. Check around the intake manifold for an air leak, then maybe on the top part where the throttle cable goes in. When that is done tune your idle and try it again. If it keeps bogging you might need another main jet for the carb.
 

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The colder it is the bigger main jet you need.
 

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French Fries N Cheese
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these bikes are chinese and not properly assembled... also the motors they put in them are blower motors not really designed to be in a bike.. tuning depends on the climate/elevation where you are, this is why you need to change the jets to get the carburator to run at it's best, get a better burn, more power and control the mixture. It is to compensate for the fact that the only other adjustment is the idle screw. They are the simpler model carbs out there and the easiest to tune.
 

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Pull the sparkplug to see the color of the tip...What you describe as a lean burn condition or possible loose carb could also be reedflutter..........

If the plug is black you re experiencing reedflutter,,,If its white or grey you have an airleak or are running lean
 

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Discussion Starter #9
I'll take picture tommorow(Danish time)!

But i found Out of, When it die and the motor stops, it Can't start, i have to wait 1 min. And then i Can start it and drive i bit again, also with semi High RPM? :)
 

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French Fries N Cheese
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As cam said it could be a lean condition or air leak in the intake... The carburator is probably the first place to start looking after you checked spark plug condition..
 

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You need to mod the IDs of the tank outlet thru the turn off valve & JB Weld and bigger fuel lines and a vent in your gas cap if needed
 

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I'll take picture tommorow(Danish time)!

But i found Out of, When it die and the motor stops, it Can't start, i have to wait 1 min. And then i Can start it and drive i bit again, also with semi High RPM? :)
sounds like reedflutter.........Im also gonna say the sparkplugs gonna be black..............
 

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French Fries N Cheese
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Plug looks like its OK to me, the tip is golden brown the way it should. The reeds could be fluttering still.. If it were an air leak or lean condition the plug would be grey and dry. Your idle adjustment might be wrong, probably too high. try slowing the idle down a quarter turn at a time, ride it and see if it gets any better. the idle adjustment is the brass spring loaded screw on the side of the carb.
 

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The cases have to be air tight, if reeds are leaking the engine will be gutless, It's happened to all of us. If it has the tin reeds, take the 2 screw off and try turning the reeds over see if it looks any better, do not over tighten, better to use a drop of blue thread sealer or get a $10 carbon fiber reed online. I use a bright flashlight and shine thru the carb side, and look for light.
 

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Here some pics of my sparkplug...




The insulator needs to be richer brown like caramel and the outter ring needs to be less black ...........

You have two contradicting burns....Try bumping the c-clip on the needle down 1 notch after you change the reeds,,,,,,,,,,,
 

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Discussion Starter #20
Plug looks like its OK to me, the tip is golden brown the way it should. The reeds could be fluttering still.. If it were an air leak or lean condition the plug would be grey and dry. Your idle adjustment might be wrong, probably too high. try slowing the idle down a quarter turn at a time, ride it and see if it gets any better. the idle adjustment is the brass spring loaded screw on the side of the carb.
Which screw?:confused:
 
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