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Joined: Apr 30, 2015 9:57:12 GMT -5
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Post by rondo on May 12, 2015 11:32:27 GMT -5
end of last year chinese scooter got harder and harder to start. put away and this year replaced carb, have spark and gas to carb, still wont start. Figured must be valves,, set valves per instructional videos and boards. First problem was no TDC marking on flywheel that i discern(?). Set sprocket with 2 small holes lined up as instructed set valves 003 and 004. Wont start,, sounds like burping through carb.....Something that struck me as odd is that i can turn flywheel with hand. After 2 rotations I feel compression, but with a little harder twist can spin right out.... Im thinking bad rings, piston??? Any and all suggestions appreciated!!!  Rondo |
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Post by ramblinman on May 12, 2015 12:37:28 GMT -5
i've never seen a flywheel without timing marks so i would double check the valves first.
if you are positive they are set correctly then it's either time to purchase a compression tester or go ahead and pull the cylinder. you'll need new gaskets and new rings, hone the cylinder, reinstall everything correctly and you should be good to go.
i recently had low compression from improperly installed rings or somehow they moved over time. when the gaps lined up it dropped my compression to 100psi (warm) causing difficult starts and erratic idle.
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Post by steve on May 12, 2015 16:45:41 GMT -5
I can turn my 50cc , which is now 83cc, by hand, no problem. Exactly as you say. The compression goes out when the exhaust valve opens. Sounds normal to me.
Have you tried starting fluid? Vacuum leaks will make them hard to start, or if you have your idle set too rich or lean. Some motors are just hard to start. You said it was hard to start last year. Did it run OK once you started it? If so, get some starting fluid, and get it started, and check for vacuum leaks. I would try that before I replaced the cylinder.
You can tell your at TDC because there is a little wiggle in the valves. Try to wiggle the set bolt, then move it to where you think TDC is, and give them a wiggle. Sometimes I have to spin it a couple of RPM to get them to wiggle. I don't know why.
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Post by steve on May 12, 2015 16:49:35 GMT -5
Also, those starters suck oil in the coil of the motor over time, and slowly get weaker. The starter could have lost speed slowly over time, and you not noticed it. I just replaced mine for that very reason. Try kicking it with starter fluid, too.
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Post by geh3333 on May 12, 2015 22:11:27 GMT -5
You should be able to turn the flywheel by hand , that's really not a concern at this point. Its become harder and harder to start. Do a quick battery test . use jumper cables and jump the scoot from a car. If you battery is low , the scoot may not start . Thats a pretty common situation with these scoots. Your battery may seem to hold a charge but you need to test it under load. Or just jump the scoot. If the scoot starts when you jump it this means your battery is junk , or the battery just need charged , if it even holds a good charge.
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