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Hello to those who read this. I bought a 1997 Polaris Xpress 300 from a guy and it was not running. Came to figure out that I only had 30 psi compression and had to rebuild the engine (new piston head, piston rings, wrist pin bearing, and piston rod). Got it running and was having problems with the idle racing and fixed it by turning the idle screw. The push start wasn’t working so I wired it up and got a battery for it so that I could use the easier starting method. But it takes forever for the engine to turn over and I have to hold down the starter for a hot minute before the engine turns over. If anyone could help me with any ideas on what could be causing it to take forever to fire up that would be greatly appreciated
 

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If by "turn over" you mean it takes a long time after you press the button to start cranking, then you have a bad switch or a bad connection.
If you mean it cranks a long time before it starts but runs ok once started, then you likely need the valves properly adjusted and check out the fuel delivery and choke/enrichener operation.
 

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If by "turn over" you mean it takes a long time after you press the button to start cranking, then you have a bad switch or a bad connection.
If you mean it cranks a long time before it starts but runs ok once started, then you likely need the valves properly adjusted and check out the fuel delivery and choke/enrichener operation.
I believe the 97 300 is a 2 stroke - no valves.........

Need to check the compression to verify it is over 100 PSI - all too often I have seen a STD piston installed in a .020 over cylinder - it starts and runs fine (maybe a little noisy), but by the time the rings seat and it cools down, the compression drops and it will not start, or takes a long crank and fiddling with the choke and throttle to finally start or it might only start with starting fluid - does that a couple of times and then won't start with dynamite.

What bore size is it and what was the piston clearance upon assembly? What did you measure the ring end gap at with the rings about 3/4 inch from the top of the bore?
 

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Discussion Starter #5
I believe the 97 300 is a 2 stroke - no valves.........

Need to check the compression to verify it is over 100 PSI - all too often I have seen a STD piston installed in a .020 over cylinder - it starts and runs fine (maybe a little noisy), but by the time the rings seat and it cools down, the compression drops and it will not start, or takes a long crank and fiddling with the choke and throttle to finally start or it might only start with starting fluid - does that a couple of times and then won't start with dynamite.

What bore size is it and what was the piston clearance upon assembly? What did you measure the ring end gap at with the rings about 3/4 inch from the top of the bore?
It was standard bore size(74.5). And I’m not sure what you mean by piston clearance.
 

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The clearance between the piston skirt and the cylinder wall - typically .04 mm (.002") (see chart) - it's worn out and needs re-boring when the cylinder measures 74.65 mm - who measured the cylinder and was it done with a micrometer or a vernier caliper? The measurement has to be taken about 1/2 inch down from the top of the cylinder from front to rear (this is where the greatest amount of wear takes place).

139473


Based on my experience I find it difficult to believe a 20 year old two stroke is still at a standard bore size - most are re-bored within 5 years of purchase and 99.5 are bored at least once in 10 years - 25% are parted out in 15 years and 50% are no longer repairable in 20 years and 99.9% are not worth the cost of repairs to keep running.

You didn't answer the question about the ring end gap and the current amount of compression. Again, a std piston will easily go into a 75mm bore, but the ring end gap will be excessive.
 
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