Clinician
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Post by kiwibilt on Dec 18, 2012 0:54:55 GMT -6
It bogs from mid range to high RPM & adjusting the idle/mixture screw makes NO difference. Im thinking that the CDI or coil is not providing enough voltage to give them enough spark ?. This is determined by the output of the magneto/generator. Can this output be checked  The plug fouls while I am trying to tune it And it backfires under load |
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Clinician
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Post by kiwibilt on Dec 18, 2012 0:41:09 GMT -6
The "wheel" still maintains full travel after I connect the cable, It just seems to "bog"...just like a chainsaw that needs adjustment.
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Clinician
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Post by kiwibilt on Dec 18, 2012 0:16:51 GMT -6
Im having MAJOR problems with getting these scooters to run... I have accessed the idle enrichment screw, but it has no effect what so ever. They run fine "out of the box" for maybe 50km & then they start to die going up hills. The scooters my boss is importing now have been sitting since 2011 (he imports them from Canada). Most of them seem to have voltage problems which I guess affects the ignition output (CDI, Coil, etc...). When running, the battery voltage is around 11.8 on my mulimeter & the latest one I assembled has no power from the mag to the auto choke or headlights & tail light (yellow wire). It seems that I can get them to idle & rev out prior to connecting the throttle cable..but once the throttle cable is comnnected & adjusted for free play...they wont wind out & lack power up hill. A mechanic at our dealership in Canada said that plugging the vacuum hose from the right side of intake will make them run richer, but this just makes the one bike I am trying to get run now die. Im ready to go back to basics & check the static timing in relation to the camshaft (at TDC). Can I check the output of the mag ? ( it's AC ?). At idle, ALL these scooters surge & die, & when you rev them, they cut out, which makes me think the auto choke is malfunctioning (apparently a common problem). With the feeler gauges I have now, I am unable to set the valves tighter than a tight .008 inches...does this make a big difference...even the new bikes come back after 5okm with these same problems. I take pride in my work..& the better I can get these scooters to run, the more work I will get, as there is nobody else here thart will touch them. I know at 1.9 HP, they are gutless...I just need to get them to run without lacking power & cutting out....Aaargh !!! I make sure the intake tube is tightened to the head & carb, & also spray starter fluid around the carb to check for vacuum leaks...is there something else I may be missing |
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Clinician
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Post by kiwibilt on Dec 14, 2012 0:22:39 GMT -6
Thanks Alleyoop,
I just downloaded a manual, but the info you provided on accessing the mixture screw wil be very helpfull. Im going to check the static timing as a matter of course now, but these bikes just seem to run lean after a while. It will also be handy to check the resistance of the coil/CDI/auto choke etc. The previous mechanic simply replaced parts in a process of elimination, so I have a bunch of spares that probably still function fine.
Would the altitude these bikes run at have anything to do with there lean condition ?.
Mahalo
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Clinician
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Post by kiwibilt on Dec 13, 2012 23:14:15 GMT -6
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Clinician
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Post by kiwibilt on Dec 13, 2012 22:44:25 GMT -6
Aloha,
I've just started working for a company that imports Chinese 50cc 4 stroke (GY6) scooters for sale & rental, & I am responsible for their assembly, maintenance & repair. They have a large fleet of which the older models are approaching 300 to 450 km. All of these scooters run like s**t. And I'm having difficulty figuring out how to tune them correctly. I am hoping I may get some definitive answers here.
1) What is the correct valve clearance ?. The owners manual shipped with the scooters says .3 mm, & the dealer in LA says .03 mm.
2)The Kei Hin carbs on the new models have NO idle /air adjustment. I was trained to adjust CV carbs by attaching the throttle cable after setting up the correct idle/air mixture adjustment then backing off the idle screw to obtain correct idle. The cable adjustment at the carb was only used to maintain tension on the throttle arm, & the adjustment at the throttle end was used to remove throttle free play (if the cables not stretched). I'm finding that after setting the carbs up this way~
a) they will not restart without pumping the throttle
b)the engine dies if you wind it out then release the throttle
It seems like you need to use the cable adjustment at the throttle end to keep them running, or max out the idle screw on the carb.
The carbs seem to be getting adequate fuel through the petcock/regulator, but they keep cutting out & lack power from idle to mid range, with occasional backfiring. Should I just stock a load of rebuild kits, or should I convince my employer to replace the carb with a better/tuneable version.
3)What is the rated output of these ignition coils & can I test them with my multimeter
4)Can the timing be adjusted, & has anyone heard of the static timing preset at the factory being incorrect or "shifting" after 300 to 450 km.
5)Where is the best place to find a service manual for these bikes (in English LOL).
Thanks in advance for any advice & as I have a busy holiday period ahead, I truly appreciate your prompt response.
PS...All these scooters are run at sea level to 1000 feet in a tropical environment.
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