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View Full Version : Backfire, now no spark!


Hair Bear Bunch
05-25-2007, 05:19 PM
Hi, My 250 es has been running quite well but it suddenly started backfiring and stopped. Tried kicking it over but it kept backfiring, now there is no spark. I've changed the plug for a known good one and had the left cover off but I can't see anything obviously wrong. Is there anything in these symptoms to suggest an easy remedy? Thanks.
hadar
05-25-2007, 06:59 PM
Flywheel key? I don't know man. I would check the ignition 1st.
Levithan
05-25-2007, 10:13 PM
Check the flywheel. That happened to be on my old 200x and it turned out that the crank bearings spun inside the motor, ruining the case. I could move the flywheel up and down about half a centimeter as well! Well, I hope its not that bad. Good luck!
BigRedRunner
05-26-2007, 12:00 AM
Bad CDI, or coil.
bigreddaddy
05-26-2007, 01:06 AM
Maybe plugged exhaust? Fouling the plug? Check spark with a new plug holding it against the head.
Hair Bear Bunch
05-26-2007, 04:28 AM
Hi, thanks for the suggestions. Hopefully I'll get time to go into it further today. I'll let you know how I get on...
Hair Bear Bunch
05-26-2007, 05:56 PM
Well there you go... I went through the coil and the sender with a calibrated Ohm-meter and all measurements were within book spec. So I changed the plug again and with a very small gap I have a small spark and it runs, ( ran it for about 2 hours, not run hard, just pottering about!) but if I set the gap correctly there doesn't seem to be enough power to give a spark. Does this mean the coil is bad even though it meter tests correctly?
Would a new coil unit solve the problem?
Tri-ZNate
05-26-2007, 07:52 PM
It having spark doesnt say very much. What color is the spark? Orange mean WEAK, should be blue
BigRedRunner
05-26-2007, 09:39 PM
Well there you go... I went through the coil and the sender with a calibrated Ohm-meter and all measurements were within book spec. So I changed the plug again and with a very small gap I have a small spark and it runs, ( ran it for about 2 hours, not run hard, just pottering about!) but if I set the gap correctly there doesn't seem to be enough power to give a spark. Does this mean the coil is bad even though it meter tests correctly?
Would a new coil unit solve the problem?


What do mean by sender, the CDI or the crank trigger?
Hair Bear Bunch
05-27-2007, 03:59 AM
Hi,
The spark was a blue/white I think, almost too small to see!
By 'sender', yes I meant the flywheel trigger.
I found when I put the meter from the top of the plug to the core tip it showed 900 ohms, but from the top of the plug to the thread base it showed 1K ohm, which I'm sure should be open circuit?
Rob.