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Post by Skoot on Mar 26, 2009 19:24:16 GMT -5
Ok, as the title says, I have a 50cc 4 stroke that has no spark. Here is what I have so far...
1. Stator has 470 ohms resistance (500 +-50 is the spec)
2. Red wire with black stripe (CDI charge) puts out 47.5 VAC when cranking (50~100 is the spec, but will still function down to 1 volt)
3. Yellow wire with blue stripe (CDI trigger) is at 0.40 VAC when cranking (0.40 VAC is the spec)
4. Coil primary is 0.3 ohms (0.10 ~ 1.0 ohms is the spec)
5. Coil secondary is 3.7 ohms without the wire attached (3 ~5 ohms is spec)
6. Voltage at coil primary wires from CDI with coil disconnected while cranking is 1.5 VAC.
I'm thinking the CDI is shot. What do you think?
By the way, I found the female spade connectors to the coil were VERY loose. I replaced them with new OEM style crimp connectors (special crimp tool).
Thoughts? Input? Thanks!
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Post by medman1952 on Mar 27, 2009 1:20:51 GMT -5
Too much technical info for me. All I want to know is;
1. Are you getting spark at the plug? 2. Are you getting spark at the plug?? 3. Does the starter crank it over pretty well? 4. Does it get gas to the combustion chamber, does the plug smell like gas?
If you answer no to 1 & 2 and yes to 3 & 4. you have an ignition issue and it could well be the CDI, might just be a bad plug, coil, bad wire.
If you answer yes to 1 & 2 & 3 and no to 4 you have a fuel problem, dirty filter, kinked hose, ...
If you answer yes to all of them, adjust the valves, check the compression
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Post by Skoot on Mar 27, 2009 5:54:54 GMT -5
1. no spark at the plug 2. no spark from the coil 3. generally, no spark at all... (see thread title) 4. strong gas smell 5. plenty of compression 6. less than 100 miles on scooter 7. starter cranks the engine very well.
I'm trying to determine which component is bad (CDI, coil, stator) without having to buy all of them.
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Post by rocketdog on Mar 27, 2009 6:28:06 GMT -5
I would say the CDI box Scoot. The Stator seems to be ok and from my experience coils rarely go out all of a sudden. They usually act up first. <Act up>= They develop hairline cracks and such. They run fine when they are cold, but as they get hot the cracks expand and the coil begins to miss fire. I wonder if there are specs to test the CDI box?
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Post by crazyivan on Mar 27, 2009 8:32:30 GMT -5
i put my money on a CDI...now this would b a perfect exuse to buy a performance one
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Post by rapidjim on Mar 27, 2009 13:18:16 GMT -5
Step 6. This voltage should be a pulsating 12 vdc signal. Best way to check is with a test light. Connect a test light to ground and then probe the primary wire, it should flash when cranking the motor. The other primary lead is ground. If it does flash and you have a good ground and no spark then the coil is bad.
If the test light does not flash and since Step 3. indicates that your CDI trigger from the stator is working and assuming your ground to the CDI is good, then the CDI itself is suspect to being bad.
Good Luck
Jim
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Post by Skoot on Mar 27, 2009 18:12:46 GMT -5
Thanks Jim... No 12v at coil with the leads disconnected from the coil and connected to a DVM. Just 1.5v, kind of steady while cranking.
Oh and thanks to everyone's input. You all just reassured what I had figured.
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Post by Skoot on Mar 29, 2009 13:42:08 GMT -5
Went to Scootertronics yesterday and got a new CDI for $20. Installed it today and the engine fired right up with one kick. Bought this scooter for $200 last week off craigs list with less than 100 miles on it. The engine wouldn't start so the owner was 'tired of fooling with it' and wanted it gone. Runs almost perfect... needs a few 'tweaks'... Thanks to all that responded... I gave a few of you a bone to chew on
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Post by medman1952 on Mar 29, 2009 16:58:10 GMT -5
Glad you fixed it, don't be a stranger here. Come back and visit us.
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Post by rapidjim on Mar 29, 2009 18:26:34 GMT -5
Glad it is fixed Good Job!
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