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Discussion Starter #1
intake valves bottomed out with .000 clearance, ive done a different 570 once and got it set to spec and about 1000 miles after they were bottomed out again, why do they keep doing this? the different machine im working on now will be getting done for the first time since factory, machine has 3400 miles on it. the exhaust is in spec and doesnt need to be touched, the intakes had 470s in them both and i put in 458s and it measures .000 yet so will order lower numbers to try again till i get a reading then i will use the matrix to get right tappets, but does anyone know the reason for this happening to the intake valves? or a rhime or reason they are doing this? any help would be great thank you
 

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Anytime I work on a 2015-16 570 full size I always remove the intake tube between the air box and the big black intake plenum to check for dust. The rectangular air boxes are known to be problematic and the crankcase breather tube can get a hole burned in it from the exhaust manifold. Seven top end rebuilds in less than two years has taught me this. Just take a look at my avatar.
 

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Ok so do i need to redo the head and valve seats? Our re adjust the valves and be good if i find where the dirty air is getting in and fix the issue? Out does polaris sell harder valves? What do you suggest i do? Thanks for all the input
 

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I think the point rock and BPS are making is that if dust is getting into the cylinder and causing wear you need to address air filtration and check the breather hose. That same dust is also wearing your rings and cylinder wall and no doubt some is making it into the crankcase to wear parts there.

If the cause is soft valve seats it's probably a defect from the factory. It could be soft material used for valves or seats or it could be that the original grind angles were incorrect leading to increased wear. The Service Manual is very specific about proper reconditioning and I was unable to find information on seat replacement. The manual does state that if a valve seat is cracked the head must be replaced so I don't think Polaris gets involved in seat replacement. A good engine shop may be able to replace the valve seats with hardened seats. It's done all the time on car, truck and even small engines like Briggs and Stratton.
 
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