Well I was pumped to bring my sled out again last Saturday. It ran pretty darn well up until 6 miles into the trip. Coming to a stop sign the Drifter started to backfire and lose power. I could keep it running by fluttering the throttle but it just wouldn't make any power. I feared the worst.
I just replaced the ignition coil this summer thinking that was what made the sled die last season (like the kill switch was bumped). That particular time though, the engine would cool completely and later, I could start it right back up and ride again for a few miles. This latest snowmobile trip was different though. At first we couldn't see any spark. I replaced the plugs (originals were good and brownish). No change. I could barely get it to start and when it did, it liked to backfire and makes no power. I figured we'd leave the sled and let it cool. I drove another snowmobile, did 137 miles that day, and when going back for the Drifter, it still wouldn't run right. "Atleast it's still broken" I was thinking...and hoping it was something I could pin point easily.
Last night and tonight I did some tests according to the shop manual. From what I read here, I'm leaning towards a bad CDI.
PULSER COIL
Measured 22 Ohms (Book says 23 ohms +/- 20%): Good ... Measured about 3.5 - 4 Vac when cranking: Good
EXCITER COIL
Measured 122.3 Ohms (Book says 128 ohms +/- 20%): Good ... Measured a max of 32 Vac when cranking but other readings were lower, around 28 Vac. The book says it should be 40Vac but I'm using a Amprobe brand DMM and hoping its just the meter trying to average the voltage. Can I rule the coil to be good? I'm thinking so.
So I wonder if I should just buy a used original CDI on ebay or go with a new one which is around $120.
Also, I noticed that with the new plugs in, the Mag side plug is much more black...both are wet from cranking when checking voltages. See below...
I ended up riding another 137 miles that day on a friend's Polaris 600 Tripple. A beautiful day up near Cadillac, MI...