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Post by sherman on Jul 15, 2013 2:48:11 GMT -5
Hello everyone, my first post here and I need some help from you all.
I just picked up a 150cc Chinese Scooter from my friend but after all the cleaning it still bogs down above half throttle. It had been sitting for nearly a year but starts with some fresh gas and a jumpstart.
I have taken the carb apart and cleaned it, ran tiny wire through the pilot jet and main jet.
Starting is easy, runs very smooth and pulls from start to 25 mph. However, it bogs down when I try to open the throttle more. I tried to twist it all the way down quickly and it does pulls for half a second and starts to bog. Thanks for any input.
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Post by rockynv on Jul 15, 2013 4:17:18 GMT -5
The main jet with the slide needle in it has very small holes in the side of it that also need to be cleaned. If you removed the slide while cleaning it is very easy to put the needle out of adjustment and sometimes difficult to get the lip of the diaphragm back in its groove which can also cause this type of issue along with getting the springs out of order or by misplacing the top spring that goes between the cover and the top of the diaprhagm. A cracked or torn diapragm can also cause this kind of problem.
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Post by jerseyboy on Jul 15, 2013 8:21:51 GMT -5
Get rid of the stock fuel pump/petcock also,,they are known for problems like this...you can just put a manual petcock on from home depot for lawn mower $10,,or upgrade to a better quality one.
All in all,,make sure your fuel flow is strong...tank is well vented also..
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Post by sherman on Jul 15, 2013 17:07:40 GMT -5
The diaphragm is still soft and nice. The needle is back in the little hole. The petcock is bought brand new from a parts store. The filter is new from O'reilly but it looks different, it has a metal cartridge instead of the paper type in the original one.
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Post by ltdhpp on Jul 15, 2013 17:16:54 GMT -5
Are you tinkering with it with the airbox off?? If so, put it back on, and enjoy the ride  |
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Post by sherman on Jul 15, 2013 18:55:37 GMT -5
The airbox is in there as well as the filter.
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Post by ltdhpp on Jul 15, 2013 19:08:46 GMT -5
dang... I made that mistake with my 50cc, lol
Well, you could have a cracked intake manifold/boot, the piece between the carb and the head. Wiggle the carb around some while its running to see if it makes it run funny. Any other vacuum leak could do this, check all the hoses if you haven't already. Make sure the nuts holding the intake manifold down are snug too.
Its a long shot, but i actually found a mudfly nest clogging the 50cc muffler... mine wouldn't run at all at first, but you could just have partial blockage. You could drop the pipe down a little and make a test run...
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New Rider
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Post by sherman on Jul 15, 2013 20:59:33 GMT -5
Just put in a new spark plug in and it runs a little better now but still not going above 30. The vacuum seems good and snug.
I also found out that the oil level seems pretty high, All the "xxxx" are covered with oil when I put the dip stick back, not screwed in. I have no idea how the oil level should be like.
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Post by earlwb on Jul 15, 2013 21:16:35 GMT -5
The modern scooter engines are all set really lean, right on the razor's edge, so to speak. Anything that affects the air coming in will make it too lean (or rich sometimes too). One thing is the air filter, intake boot to the carburetor. If the large intake boot (tube) comes loose or breaks open the engine runs too lean and it won't develop any power of course. The air intake is somewhat restrictive and they jet the engine's carb accordingly. So if the air intake comes loose, the engine breathes easier and now it is too lean.
Then the rubber intake manifold is the next item that causes it too. The rubber tends to deteriorate almost while you watch. As soon as a crack or cracks get too large and too deep, it lets in air and the engine runs too lean.
Next is the spark plug wire coming loose either at the ignition coil or at the engine's spark plug. The coil has a inverted sheet metal screw and the spark plug wire actually screws into it. The spark plug wire can also screw into the spark plug cap too, but they may have a little metal clip on that end too. The problem is if the spark plug wire is loose for too long of a time, it can damage the ignition coil causing it to go bad. This is due to the extremely high voltage levels as the spark now has to jump a larger gap and that causes the insulation inside the coil to break down.
One can also have loose or bad power connections on the bayonet plugs on the ignition coil. The metal clips are soft and can become quite loose making for a poor connection there causing a power loss.
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Post by JR on Jul 15, 2013 21:18:42 GMT -5
Check the valve lash.
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