2001 Polaris indy 500 crazy spark

[toddspolaris]

Hello everyone, I need some pretty good mechanics to chime in here, anyway this is going to be a book. I have a 2001 Polaris 500 with the Fuji motor in it. It will start and act like it is loping. It is definitely a spark issue as you can put inline spark testers on both plugs and watch it. as it sits and idles, it only fires about 1/4 of the time, its consistent every time you start the sled. And both plugs firing at the same time.And when you give it throttle, the spark doesn't change and it will die cause your adding more air and fuel and it won't take it. but what I did notice is if it gets to idling very very low to almost stalling like 400 rpms then the spark changes and looks normal, but the sleds dies out because it was to low.Ok, what have I done, well the first thing we did was unplug the main engine to chassis plug, No Fix, even unplugged everything coming off the stator going to the machine even disconnected the black wire coming off the CDI box, NO FIX , So I then check the exciter coil on the stator, it was within spec of 160 ohms, so I replaced the CDI- coil box with an aftermarket SPI one, NO FIX, so I pulled the stator out and bench tested it and looking for a broken or pinched wire, See none so I replaced the exciter coil with and aftermarket one, same thing NO FIX. So the only thing that makes this motor run on spark is the Flywheel- exciter coil- and the CDI coil box. What left the flywheel? anyone ever see a flywheel do anything funny like this before.. Yes I have checked the index of the crank and what not, its a spark problem. So looking for qualified techs. to chime in here. Help I have No hair left. Thanks Todd

 

[dofo1]

Not sure of what your description is trying to say but I think you are saying that you have ruled out a bad stator or CDI so a couple of other things that can cause spark issues are bad throttle safety switch, pull handle bar cover and disconnect the wires going to the throttle block and try it again, second and third are bad connection at and/or bad spark plug caps, the caps unscrew off the wires, you can cut 1/4" off the wires and re-attach them to get a better connection, maybe replace the caps as I have seen a few go bad internally. Also I think you can unplug the ignition switch to by-pass it, don't do this with the kill switch un-plugged as I don't think you can shut it off.

 

[toddspolaris]

Thanks, tried all of that, by disconnecting the main wire harness coming off the motor that eliminates the entire machine so you only then have the stator, flywheel and cdi ign box. See why I'm pulling my hair out.

 

[dofo1]

Thanks, tried all of that, by disconnecting the main wire harness coming off the motor that eliminates the entire machine so you only then have the stator, flywheel and cdi ign box. See why I'm pulling my hair out.

Gotcha now, did you replace the spark plug caps?

 

[toddspolaris]

Yep tried everything so far except to replace the flywheel. I just cant believe a flywheel can go bad unless magnets fall out. My hair is almost gone, HELP

 

[lak7]

Possible that wires from stator to coil are bad / corroded?

 

[toddspolaris]

Aha, found my problem, decided to do a pressure test on the motor, blocked off intake and exhaust, found pto seal leaking externally. tore bottom end open to find a piece of the bearing cage broke and tore the inside lip of the seal, although the outside lip looked ok. cant believe it ran and loped as it did, and the spark followed the lope. Crazy, anyways on the way to fixing the problem. Thank goodness, now my hair can start growing back. Thanks all for advice.

 

[jonesin]

glad you found it!
are you able to pull the motor and take the bottom off to do the crank seals without disturbing the top end?
I have a long thread on here about my 2000 indy 500
long story short:
it started to idle high last year, even if I hit the choke it would idle up
right now due to running on one cylinder (cdi cable was rubbing on pull chord)
wouldnt start (needle tip broke off and allowed cylinder to fill with fuel)
now I found the primary clutch spider is in rough shape from weights rubbing and am fixing that but..
what I am wondering is with it all tore apart I am 4 bolts and disconnecting the coolant away from pulling the motor, thinking that if I could just turn it over to do the seals it would be cheap and peace of mind to check that off my list of possible problems.....
How did you pressure check the engine?
Thanks!

 

[toddspolaris]

OK, been a few weeks, Replaced the pto bearing and the crank seals, put all back together and still running the same. Put spark testers in line and watch the spark, only sparks some of the times, called the owner of the sled and He told me he had changed out the cdi box with an aftermarket one, and so did I, He brought the original OEM cdi box in and I installed it and guess what, Problem solved. Lesson learned hear is be careful using aftermarket Ignition components. Not worth it