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Post by lshigham on May 28, 2010 7:16:21 GMT -5
Hi All,
A quick question. I bought a race CDI for my 49cc Baotian scoot, as the stock one restricts the RPM. Anyway, I had to change the pins around on the connector block, as there are variations in the configuration. I used a wiring diagram supplied by the seller.
The problem is that with the new CDI the spark is weak and inconsistent, perhaps working only every 4-5 revolutions. Is it likely that the problem is a faulty CDI?
Also, could it be a problem with a AC/DC compatibility? I don't know how to check what my scoot is, the CDI I purchased is DC.
Thanks all,
Luke
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Post by cyberbeer65 on May 28, 2010 8:58:19 GMT -5
Your scooter is likely AC.
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Post by lshigham on May 28, 2010 9:12:25 GMT -5
Thanks. I asked the dealer that supplied the scoot before purchasing the CDI, but it would appear they were wrong.
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Post by capturedbyrobots on May 28, 2010 11:40:35 GMT -5
I bought a no rev limit cdi,
just to find I never had a rev limit to begin with.
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Post by D-cat on May 28, 2010 13:54:17 GMT -5
I can't be sure of the Baotians since the seem to be a bit odd electrically (I've seen the CDI pinout difference). It would be nice if they'd just make a small wiring adapter, but I've never seen one. In theory, their altertion makes sense, since there's no need to have a separate line for the speed limiter when it's included in the same block and draws from the same lead over the trigger coil anyway; they can save a couple wires and do the whole job inside the CDI block. Reality is a beoch though when the non-standard part compatibility issues arise though.
On a standard scoot, the CDI circuit is AC (drawn straight off the magneto) and completely unrelated to the rest of the bike's electricals, aside from ground. Thus in theory, if it's firing at all, it is working. You may have a bad or weak CDI, or your CDI and coil don't like eachother (upgrade to high output coil? Not a bad idea with a no-limit CDI anyway, high revs can burn out a stock coil, really sucks when you're 20mi from home). Don't underestimate the value of a good spark plug too; if you're running a junk stock spark plug, switch that out with a good NGK one.
First thing though I'd think would be to get a repair manual for your scooter, check against the QMB139 manual available various places on-line (pg 23 is the wiring diagram) and see if the pinout alterations in your instruction set make sense and just double check that you performed it correctly. If it is done correctly, see if your local shop can test the CDI. Assuming it's good, start looking at other possible causes.
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Post by lshigham on May 29, 2010 0:59:20 GMT -5
Here is the page from the manual. Would it be possible to rewire the CDI to run directly off the battery, instead of the magneto? ''On a standard scoot, the CDI circuit is AC (drawn straight off the magneto) and completely unrelated to the rest of the bike's electricals, aside from ground. Thus in theory, if it's firing at all, it is working. You may have a bad or weak CDI, or your CDI and coil don't like eachother (upgrade to high output coil? Not a bad idea with a no-limit CDI anyway, high revs can burn out a stock coil, really sucks when you're 20mi from home). Don't underestimate the value of a good spark plug too; if you're running a junk stock spark plug, switch that out with a good NGK one.''I also would have thought if it was wired up wrong it would either work properly or not at all, that's why my first thought was the CDI was faulty. I did intend to upgrade my coil soon, with the next round of changes. I have a nearly new NGK Iridium spark plug, so that should be fine. I have attached the page from the manual. Attachments:
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Post by D-cat on May 29, 2010 6:38:20 GMT -5
Judging from this image:  The pinouts are exactly the same to relative position when both held upright. This means that no wires should have been cut or switched to a different place, simply slid into their connectors matching the original locations. I guess they're not all that different after all! |
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Post by lshigham on May 30, 2010 12:21:55 GMT -5
The problem I had is that the bottom middle pin on my old one isn't a ground, but a pin for the speed limiter. The redundant pin is in a different place on my old and new CDI, which is what was causing the problems. I have purchased an race AC CDI instead, which should work out of the box. I live in hope, anyway!
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