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Discussion Starter #1
Watching vids on youtube I've noticed that aftermarket exhausts on the 850's sound sooooo much better than the same exhaust on the 800. Is it simply the cam? Would a cam swap in the 800 produce the lower, throatier tone like that of the 850? Or is the 850 just a totally different configuration all together, internals and what-not? The 850's produce an almost muscle car-ish sound, which is what I'm after.

Joe.
 

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With the 850 producing 30ish more HP Id assume it gives the back pressure more room to sound different.
 

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Not 100% sure on this but
Doesn't the 800 engine both pistons move up and down together and the 850 1 is up and the other is down?

The 850 is not a parallel twin like the 800..it is an inline twin with the pistons 90/270* apart on the crank. That combined with it's firing order make it perform/sound much like a V-twin. It makes the 800 seem like it should be in a tractor. The 850 has to be the smoothest ATV engine I have ever ridden and it has nice power delivery and gets better mileage than the Polaris 800.
 

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Discussion Starter #5
That would make sense then as to why it resembles more of a deep V-twin sound. I bet even a healthy cam wouldnt produce the same type of sound as the 850 (although it would have to sound better than stock).
 

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I thought? that all Polaris Twin engines had the 2 pistons travelling in mechanical phase but 180 degrees out of phase so while both pistons are say in the upward stroke one will be in the compression stroke while the other will be in the exhaust stroke. This gives good power and smooth torque, tis easy to check anyhow, remove your plugs on your XP, rotate the engine with the starter until one of the cylinders is on Top dead centre and simply measure the depth using a plastic rod (drinking straw, knitting needle etc. but engine needs to be cold for this) then measure the second cylinder depth. If both are the same depth then the pistons are in mechanical phase, if it's the depths are different then they are out of mechanical phase (I would guess 180 degrees).

Regards - MM :)
 

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I have the same exhaust on both my 500 and 700. The 500 has a deep throaty thump like a big single should have. My 700 is higher pitched and sounds more like a tuner. I have always wondered why. My buddy has the same Big gun exhaust on his v twin brute force and it sounds like a Harley.
 
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