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Discussion Starter #1
I thought I would start a new thread, so that people can better search for the solution in the future if they have similar issues like I have had. There are too many threads that say the engine is running bad. In my case, I now know what the issue is, so might as well start a thread on it.

The Timing Gear slipped on my 2013 Scrambler 850 XP.
I will be taking pictures along the way and keep everyone posted with progress.


Scrambler XP engine by rangerbob316, on Flickr
 

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Did the chain jump a tooth or did the timing gear itself move? Is there a keyway or just press-fit? On a side note, my son's hockey team just played a tournament against a team from Kitchener and a few others around Toronto.
 

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Discussion Starter #3
I won't know for 100% until we get the motor out.
It appears the gear slipped. They are pressed on. I plan to weld it. The upper one has a shear pin so that should fail in the future
 

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Hmmm, I would've assumed both were key'd. I would think a small tack weld would do the job.
 

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Discussion Starter #5

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What's the easiest way to check the timing? I have all my plastics off now playing with tps. Would like to check this before I put it all back together if possible.

Sent from my SCH-I545 using Tapatalk
 

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Wow that timing gear slipped a good amount. I think tack weld would be a good idea to prevent future failure.

Sent from my SCH-R970 using Tapatalk
 

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Discussion Starter #8
What's the easiest way to check the timing? I have all my plastics off now playing with tps. Would like to check this before I put it all back together if possible.

Sent from my SCH-I545 using Tapatalk
I can't answer for you, my dealer hooked it up to his computer and it told him.
After he pulled the cover off the top, you can use a flashlight and look down in to the motor and you can see the two tabs that SHOULD be lined up.
 

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My cam gear turned with 70 miles on the quad. Ruined the entire motor. Polaris told me they were going to rebuild the motor, I fought them, and got a brand new motor installed. I'm not happy with the quality of these machines!
 

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My cam gear turned with 70 miles on the quad. Ruined the entire motor. Polaris told me they were going to rebuild the motor, I fought them, and got a brand new motor installed. I'm not happy with the quality of these machines!
is this a common problem?
 

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70hp is more than my first diesel Rabbit had and that was a 4 cylinder car.
The timing gear and flywheel should be keyed to the crank or the crank should have 2 flats machined with a match mark to orient them. The match-marked flywheel and gear should have a mating double D hole. The mechanical engineering intern that did this one need his head examined.
 

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Discussion Starter #14
just an update....
the piston smashed the exhaust valves. new ones on order, but there is a two week back order on them.
I'm still in shock that this happened and still wonder why the darn thing failed. Dealer is still saying water got in to cylinder. I'm not ruling it out, but I'm having a hard time figuring out how the water got in there...
Gotta look for a leak in my snorkel setup
 

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just an update....
the piston smashed the exhaust valves. new ones on order, but there is a two week back order on them.
I'm still in shock that this happened and still wonder why the darn thing failed. Dealer is still saying water got in to cylinder. I'm not ruling it out, but I'm having a hard time figuring out how the water got in there...
Gotta look for a leak in my snorkel setup
If it ingested water you'd find a bent connecting rod and maybe damaged pistons not a slipped timing chain gear with bent valves.

From orbit via Android.
 

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Discussion Starter #16

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was it covered under warranty? because as said if it ingested water it would have bent one or both connecting rods. water doesn't like being compressed.
 

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Discussion Starter #18
dealer just gave me the goods news.... Polaris is covering the cost of the repair!!
I called in to Polaris a few days ago to argue my case, citing that fact the Scrambler 500's have a keyed CAM gear, why doesn't a big bore like the 850???
My dealer hit up Polaris with the same argument on his end, and four hours later....
Free repair for me :)

Parts are still on a two week back order, but now i can sleep at night.
 

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Thats great news Bob...they did you right....I would like to see the melted plastic victims done right now....enjoy the machine when you get it back....its been away for a while...again congrats
 
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