Snowmobile Repair: Ignition, hard starting, best bet, stator

Question
I have a 1999 Polaris Trail RMK. I have no spark. I have followed the service manual troubleshooting guide and it appears that my CDI module is not working. (The stator and coil resistances were all a little low.) I found a used module from a 2002 Polaris Supersport (same engine as the Trail RMK as far as I know). The part number is slightly different. Do you know if this is just a newer part number? The original number is 3085700. The 2002 number is 3087106. (Any qualms about buying a used CDI? It is off of sled that was running)

The second question: Toward the middle to end of last season my sled began to become very difficult to start.Previously it would start down to 20 below on three or four pulls! I checked the compressions (cold, as it won't start due to the above problem)Both cylinders are 115 psi. Is this acceptable? Any suggestions on hard starting?

Answer
Hello Mark,

   Sorry for the delay in my response. The CDI boxes are differently designed, so I would in no case, use the 3087106 part. You can however, use the CDI unit from a 99 Supersport. If you find any CDI units, and aren't sure if it will fit, don't hesitate to let me know, and I'll look up the P/N, to see if it's useable. One thing, that is more failure prone, than the CDI, is the coil. Although, your best bet would be to take the coil and CDI to your dealers for testing, a coil is very low priced. You can get one here; http://216.37.204.202/polaris_oem/PolarisSnow.asp?Type=12&A=242 if you want to go that route. For a CDI, They sure are expensive. The cheapest I can find would be around 250, which is through www.ronnies.com  .  Ebay, as well as www.alssnowmo.com , are ideal places to look for used ones. The reason for the hard starting, was probably an indicator, of the problem you have now. It was probably getting a weak spark, when you tried to start it. Things to check anyway, would be your spark plugs, fuel filter, a clean carburetor, as well as checking the fuel impulse line going to the fuel pump. Hope this helps you. Let me know if you have any other questions at all. Good luck with the Polaris! --Arcticatman