My xp 900 won't start

[hdkawi]

Just put a motor in my 900 and it turns over just fine with the plugs out put the plugs back in and it can barly make through the compression stroke. So I put a new battery then a starter in it and on luck . Is there a auto decomp on the cam or am I missing something

 

[papajake]

did you rebuild the engine or is it a crate sounds like the valves are not opening

 

[the_real_wild1]

did you rebuild the engine or is it a crate sounds like the valves are not opening

Yep better do a valve set to verify

 

[hdkawi]

It's a used engine so it could b anything
I will check the valves

 

[hdkawi]

Checked my valves exhust valves r good and 2 intake valve r good and two r very close to spec .004 a little tight so it should run.
Exhust is .011- .013
Intake is .005- .007

 

[174mcx]

If it will crank over with the plugs out there is no contact with the valves. I doubt there is a decompression on that motor. I would still lean in the direction of your original diagnostic, maybe the ground strap from the motor to the frame is on the wrong side of a rubber mount or a wire is mostly broke off in the harness. I would say there is not enough amps at the starter to turn it over so if you changed the starter and the battery I would look at the wiring side of things. Did the replacement motor come with any wiring harness or is your old harness used?

 

[174mcx]

after reading my reply, are they the right plugs? maybe there threading in to far and contacting the piston?

 

[hdkawi]

I have check some of the conections and cleaned them. When I crank it over for a bit the wire will get very hot at the starter started to melt the cover does that mean there is good power going to the starter

 

[hdkawi]

I will check the ground strap
I'm using my wire harness

 

[174mcx]

Okay, yes the hot wire shows good amps going to the starter, no need to check the ground strap anymore if thats happening. It was a new starter you installed? what happens if you hook battery cables to a second battery (either a spare battery or your truck) and ground to the block of the motor somewhere and touch the positive right to the starter post? if it doesn't change anything its inside the starter or motor, if it cranks good you have a battery / wiring problem. So this motor you got whats the story there?

 

[174mcx]

usually a decompression is used on something that the starting system has a limited amount of power. Such as a chainsaw, the rope will break or the person pulling it is not strong enough without the decompression. Or a dirt bike, the person is not strong enough to kick it over properly without decompression. In the application of the ranger I would believe polaris would have just installed a stronger starter system instead of making a decompression system.

 

[QMAO]

I had a problem starting my 2012 900xp. It was hard turning over when starting. I found that the idler gear between the starter drive and the one way sprag bearing was to close and the gear teeth were binding.
Big Starter problem rzr 900 xp - Polaris RZR Forum - RZR Forums.net

 

[hdkawi]

I found the problem I didn't ground the starter

 

[hdkawi]

starter works great now but it jut spins now it will engage once in a while im thinking the one way bearing is gone and I need a special puller

 

[hdkawi]

Anyone change the starter bearing ? Can I change just the bearing or should I replace the
Bearing and race , or change the bearing and gear

 

[hdkawi]

I changed the bearing and got it running thanks to Keith and al. The dam spark plug boots were to short