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Discussion Starter #1
Im in a similar boat. Ive got a 2005 polaris ATP 500ho and seems to have a weak spark to me. New cheap carb, new fuel pump, Measured 500v from the cdi out, tried a different stator / pickup with the same results (185 ohms on trigger and 0.3 on stator), different coil pack (0.2 on primary and 12k on secondary, adjusted valves to 0.006, compression is 50 on stone cold and 70 with a little oil. Swapped ECM, Is it just the low compression numbers? Factory service says 50 - 100 psi. The kicker is I do not have the original cluster but was told it ran without it but no 4x4. It has been sitting for around 4 years. Starter fluid doesnt seem to have any impact and really need some expert advice.
I started a new thread for you and will study the info
 

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Im in a similar boat. Ive got a 2005 polaris ATP 500ho and seems to have a weak spark to me. New cheap carb, new fuel pump, Measured 500v from the cdi out, tried a different stator / pickup with the same results (185 ohms on trigger and 0.3 on stator), different coil pack (0.2 on primary and 12k on secondary, adjusted valves to 0.006, compression is 50 on stone cold and 70 with a little oil. Swapped ECM, Is it just the low compression numbers? Factory service says 50 - 100 psi. The kicker is I do not have the original cluster but was told it ran without it but no 4x4. It has been sitting for around 4 years. Starter fluid doesnt seem to have any impact and really need some expert advice.
I started a new thread for you and will study the info
Thank you! Also hooked up compressed air (90psi) to the spark plug hole and didnt hear any hissing or air escaping. Measured 12 volts in and out at the keyed switch. IDK what else I should try.
 

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Discussion Starter #3
Have you checked the spark from the coil wire to ground? You might have a defective spark plug or spark plug cap making the spark weak?

If you have sufficient compression, fuel and air in the right ration, spark and spark at the right time it will run.

From the values you have published and according to the service literature information and the fact that you have spark, pretty much eliminates most of the ignition system as a problem. It is coming down to battery voltage while the engine is cranking, the voltage at the tip of the plug and the condition of the plug itself.
 
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