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Post by peachy on Sept 27, 2016 0:25:20 GMT -6
Hi all, I'm hoping you can give me a bit of insight here. I have a gy6 Chinese scoot that is giving me problems
It came in with a seized engine from running without oil, and so we replaced the barrel and piston, after checking that the crank was not damaged. Then it ran again, but not well. When we revved it, it revs and revs up to a point where it then starts to intermittently stop firing, as if it was not getting spark or a valve was sticking.
So we looked at the valves, found that the cam's decompressor ratchet was broken, and so we got another one. Still no change. Checked the carb with another we know works. Still no change. We found the intake manifold was cracked so we replaced it and it continued. We have replaced the valves, head, checked with another coil we know to be fine, set the tappets multiple times (currently they are .10-.12mm for intake-exhaust)
Checked the CDI with a brand new one out of the box, made sure the coil wires are making good contact, and checked the spark with a timing light. It still continues to do the same thing. I drove it around for the weekend and it never once cut out of did anything wrong, except for at higher revs dropping fire every 2 seconds or so, as if someone was flipping the kill switch on and off and on and off.
We have also checked the fuel line, and the quality of the fuel and found no problems.
Any ideas? I'll take anything at this point
Thanks in advance,
Peach
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Post by peachy on Feb 12, 2016 8:43:43 GMT -6
Hi all, I have a skygo sg250st-5 quad, and I need to know what type of cdi it uses? DC or AC? It's not charging (dies without a battery), and is intermittent in starting, even after we checked the fuel and air. I want to know because then I know what to check for, before buying a new cdi or R/R.
Thanks
Peachy
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Post by peachy on Jan 27, 2016 0:25:53 GMT -6
Ahaaa, that makes sense, because it seems that the scooters that haven't got the little boxes lights turn on without the engine running, ie. they run off the 12v circuit
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Post by peachy on Jan 26, 2016 12:38:54 GMT -6
Thanks a lot for your answer  Here's a picture of one of the boxes I'm talking about, it was on a Yamaha Invader 100cc quadbike, which was not charging, according to the client, and the original battery was dead.  There was also a SYM/Honda Duke 125cc which had two, a smaller one and a bigger one. I think it's more likely that they are something to do with the lights. I think I'm gonna have to find a new multimeter, because the current one is pretty old, seems like the DC section is a bit iffy. The ac section works though; reads about 20-30 volts ac at engine idle, which is I believe correct I'll be at work again on Friday . I started to work at a little scooter/quadbike repair shop recently, and I'm the most learned (relatively) in the electrical side of things. Something still feels off about that Yamaha, and a few other bikes came in with dead batteries too, so I want to be clued up about these things  ? Thanks again, Peachy EDIT: another thing, the box for the Yamaha has two wires coming out, All the rest have just one wire |
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Post by peachy on Jan 26, 2016 2:43:11 GMT -6
I badly need an explanantion of every part in the charging circuit and what it does.
I've seen a few different scooters, and some of them have just R/R's, some of them have R/R's and a little metal box with just one wire going into it, and some of them have two metal boxes, and one had a little black box with four pins and yellow and white wires
It's just ridiculously confusing and I can't find anything on the internet that doesnt explain what i already know
Here's how i understand it. We have the stator, it makes ac power when the engine runs, this goes to the R/R to be turned into DC. Because the AC voltage rises with the revs, the R/R has a zener diode or something inside it, --as well as a (full bridge? half wave?) rectifier-- that gives a dummy load when the revs and AC voltage goes up, dropping the voltage (does it load the AC circuit? Or the DC circuit after it's rectified?) so that we have a steady 14.6 volts for the battery to charge on, and to run the lights, etc.
Here's a few things i dont get
1. Why on earth would a new battery show 15v DC, with nothing connected? Is it a problem with my multimeter? Is it because it's (the battery) new?
2. To tell if it's charging, i would assume when the battery is connected to the charging circuit, the voltage goes up as you rev, to, prefarably 14.6 V, but what would it be if the battery voltage was higher? should it go down because the diode activates? Would it go up more, to say 18 vDC beacuse they add or something? (i once measured that on high revs)
3. what is the purpose of those metal boxes? are they spare doiodes? Are they for the lights? What the heck do they do? I opened one and it was just a wind of (probably resistor) wire around a glass core. The engine runs without it, and the battery appears to charge as well.
I have a reasonable amount of understanding about electrical principles, etc. but if i dont know what a thing does, then i cant tell why/if its broken. and I'm worried I'm gonna mess something up or blow something working in the dark like this.
Thanks,
Peachy
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