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X1 Pocket Bike 43cc - Rebuild

5601 Views 21 Replies 5 Participants Last post by  EPR
I bought a pocket bike for $40 didnt run so I decided to rebuild all of it.. After taking the whole motor apart I Found there was no gaskets besides intake, the piston was scored and the cylinder was full of metal shavings from the piston bc the fuel was lean ( not enough oil in the mix ).

I cleaned the entire inner&outer of the motor and got it ready for the rebuild. Ordered the entire gasket set, a Tornado UFO Performance Air Filter, a pullstart, and a 40mm piston/ piston rings set.

I took the wheels off and all the plastics, leaving basically just the wiring on it. Brakleened te whole thing to clean it, wirebrushed & sanded all of the surface rust on the frame and bolts and adjusted the fork/ steering alignment.

I modded the flywheel to reduce drag with a Dremel to grind the extra fins down and used a hand file and sandpaper to finish it.. If you dont have a dremel you can use just the file or a hacksaw to cut the fins off, will only take longer.
To make a higher clutch lock up amd faster take off i cross drilled 4 holes with a 5/16 drill bit... Also used sand paper to roughen up the clutch shoe pads and deglazed the clutch bell

Will update over next few days with more pictures & info on new parts

Any questions on disassemling the engine just ask
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Unless you want to lessen power dont use a basegasket when reassembling the engine........Port the intake and exhaust ports 1/8" wider each side of them each and raise the exhaust port a 1/8" aswell to enhance the lowend to midrange powerband ....Modify the WYK rep carb and intake manifold aswell and get a rocket key to advance the timing......Good Luck
When you need a new piston or cylinder get a 44mm, 49cc set, think there the same price as 43cc.
I was gonna port out the intake and exhust but ik it has to be done perfectly and i dont know how to
CAM2 has tons of photos and text on how to do it by hand. Cag, Cags, and more Cags thread, 62 pages skim through till you see the cyld mod photos on Cags and piston ports I believe.
I was gonna port out the intake and exhust but ik it has to be done perfectly and i dont know how to
Thats true for eurobike engines...chinese engines are more forgiving because they were designed for lawn equipment.........follow the basic porting rules and youll be ok...............

The exhaust port gets widened 1/8" on each side..The port gets raised .045" in the center and tapered down to the widened sides.....You dont grind the bottom of the exhaust port at the cylinder at all........

You widen the intake port the same 1/8" on each side only and portmatch the outter part of the intake port to the intake manifold

purgeport hole gets drilled open to 1/8".......
Anyway I can change the exhaust sound without buying a performance muffler?
you can open up the muffler and fill it with packing to make it less noisy if thats what you mean, but as far as changing the actual sound, unless you mod the pipe it will pretty much stay the same. If you go for a performance exhaust it will only get louder, but the sound will be slightly different.

as you can see the aftermarket exhaust is much less restrictive than the stock.

X1 exhausts:


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If you have access to a welder, you can mod your own pipe. I get a 2 7/8" ID diesel truck pipe extension to make a bigger belly, $20, I will make 3 exhausts mods from it or $7 a pipe, even if you have to pay a muffler shop $30 to weld it up, you will have a great pipe. You need to cut aleast 4" from your head pipe on a Cag maybe not on yours, CAM2 would know better than me and add 4 or 5" of big pipe in the middle. Here is how you start.


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So it was running great today for about 20 minutes tyhan it stalled out and wouldnt start... i noticed the primer bulb was so full that i couldnt even see the fuel moving around.. also took out the spark plug (which was mint when i put it in) and realized there was no fuel on the spark plug it was already looking fouled... also top of the piston had some debree on it and appears pretty dry as well, and i know it was all clean when i put it back together.. any ideas?
Fouled as in black and oily or grey and dry? and you found metal debris on the piston or did it just have black carbon deposits? Sounds like a carb tuning issue to me. When th motor is warmed up to operating temp it should be alot easier to start if anything.
So i realized i had $3 worth of gas, and i had enough oil that should of been mixed with a gallon of gas (4$).. And the spark plug was Grey and dry.. Im thinkin it was the mixture so i emptied the tank emptied the gas left in the carb and gonna mix it right and try it out tomorrow.. And yeah ive been attempting to tune it but im used to tuning 4 strokes and i cant really tell what sounds the best when tuning
If you have the 15mm pumper carb w/ the prime bulb on the bottom, the is a tiny slotted screw down inside the round brass piece on top, you Low Speed jet adj. and the spring screw on the side is the High Speed jet adj. and the idle screw on top. Your H should be about 1 1/2 turns out and the L jet about the same to start. If the pump diaphram is worn out it will not pump enough gas to run right. A new carb is 13 to $15 shipped on ebay.
Nope carb is on bottom throttles on top
Your carb does'nt look like this??


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No it does... And under the primer bulb in yhr catb is the black thing with a orange circle/boot .. That was torn so im replacing it tomorrow
i bought an pocketbike x1 with burnt wires so i took all the wires off and has no spark and won't start need help ASAP WAN TO RIDE IT
Make sure your coil is not grounded, first check the spark plug. Then check for a spark while the plug is off with wire on and outside grounded. Turn the engine over as fast as you can, low light helps see a spark. if you have a good blue spark, put gass down the carb and try to start it again and see what happens. Plugs fowl real easy on these engines. How do you know it is a 43cc engine, is the cyld bore 40mm or 44mm??
im not sure if it is a 43cc but how do i check the coil because it has no spark at all
Sounds like you need a new coil, cheap China wires & vibration, there about 10 or $12 online. Search on eBay, 43, 49cc China 2 strokes pocket bike engine parts. Make sure you get a piston port coil, it has a round rubber plug cap. You can measure the bore thru the intake or exhaust port, I can tell by just looking in the exhaust port.
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