No spark = major headache

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R

rcflier500

New Member
Nov 15, 2009
50
0
0
Upland, Ca
Hi,
A few days ago i rode my bike in the morning and it ran fine. In the after noon it ran ok for about a half mile and then backfired and died. The rest of the day all i could get it to do was backfire. I pulled the plug and saw it was wet. I reinstalled it and pedaled as hard as i could to clear out anything that might have accumulated in the crankcase to foul the plug. At this point it will not even fire. I took out the plug again, dried it off and checked for spark by grounding it on the head. No Spark.

I then unscrewed the wire from the cdi, shortened it to make sure it had a good connection and reinstalled, still no spark. Resistance in the plug wire is .9 ohms. I then checked for continuity in the kill switch, its working perfectly.
I then proceeded to hook up my multimeter to the magneto and by turning the back wheel as fast as i could with one hand i was able to get 2 VAC. Then connected the voltmeter directly to the plug post on the CDI and grounded the other end onto the head. Spinning the wheel made no difference in the voltmeter set to DC or AC.

I am at a loss on what to check next or even if my measurements are right. Any help would be greatly appreciated. :)

BTW, im using a BP6HS plug
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
RC,
Lets start with your wiring. Have you checked the connections where the blue and black wires from engine and CDi are spliced? I assume you have because you've checked the kill switch but it's the first step. You also checked the plug wire connection at the CDI but did you also check it in the plug boot. If you're using the kit supplied boot the wire screws into it like it does the CDI. If all these look good I'd check the magneto. Its not uncommon for one of the wires to come loose at the solder joint at the mag coil. The blue wire especially needs a good look and to prove continuity. Make sure the white wire is not grounding to anything. Check these and get back to us. Oh, and I'd be careful hooking a vom up to the plug wire. You could damage your meter very easily due to the high voltage that 'should' be there. Here's some ohm readings for you.
Use Low Ohm-Meter Scale About 200 Ohms

1) Check Ohms between BLACK wire and WHITE wire. Reading should be around 2 Ohms
2) Check ohms between BLUE wire and WHITE wire. Should be around 300-400 ohms.

CDI

Use Ohm Meter High Scale About 200-K
1) Positive lead on BLUE wire and Negative lead on BLACK wire should read infinite (no activity)
2) Positive lead on BLACK wire and Negative lead on BLUE wire. Should be about 130-150 K-ohms
3) Positive lead on Spark Plug wire and negative lead on BLUE wire. Should read between 135-155 K-ohms

Switch to Low Scale 20K
4) Measure between Spark Plug wire and Black lead. Should be about 2.5 - 2.7 K- ohms


Tom
 
R

rcflier500

New Member
Nov 15, 2009
50
0
0
Upland, Ca
Here is what i came up with.

1) Ohms between BLACK wire and WHITE wire. Reading should be around 2 Ohms no activity
2) Check ohms between BLUE wire and WHITE wire. Should be around 300-400 ohms. 326 Ohms

CDI

Use Ohm Meter High Scale About 200-K
1) Positive lead on BLUE wire and Negative lead on BLACK wire should read infinite (no activity)
2) Positive lead on BLACK wire and Negative lead on BLUE wire. Should be about 130-150 K-ohms 2.5 Mega Ohms
3) Positive lead on Spark Plug wire and negative lead on BLUE wire. Should read between 135-155 K-ohms 2.5 Mega Ohms

Switch to Low Scale 20K
4) Measure between Spark Plug wire and Black lead. Should be about 2.5 - 2.7 K- ohms 6.71 Kilo Ohms
 
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