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Discussion Starter · #1 ·
what I have is a 1999 zr 440 lc sno pro when I bought the sled the motor was in pieces and i put a new crank and gaskets and bearing, one of my buddys screwed up the rings so i bought another new set and when i did a compression check the mag cylinder only had 65 psi so I tore the top end back off and put another set of new rings on I also switched the mag cylinder to the pto side and put it back together, did another compression check and now with the brand new rings and gaskets, the pto cylinder had only 65 psi, there are no visible cracks in the cylinder, any help would be great.
 

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Is that the only cylinder you put new rings in?

Did you hone the bore?

What is the other cylinder reading?
 

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Discussion Starter · #3 ·
i put brand new rings in both cylinders and the other is at like 150 psi and I did hone both cylinders
 

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You have to check the bore measure meant of that one cylinder. It would seem that the rings are not sealing in that cylinder, so it must be out of spec. You know the piston and rings are good, so it must be the cylinder. I would think you could get a re-nic'd cylinder and they'd take yours as a core.
 

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Discussion Starter · #6 ·
i checked the cylinders with a micromitor and they are the same, does any one know what a set of cylinders would run for price wise
 

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Re-nic'd cylinders should be around $200US and $300 CDN, each. If your cylinders are both to spec and the pistons are to spec then something else has to be wrong with that one cylinder. The next thing to check is to check the cylinder for roundness. Make sure the bore is perfectly round from top to bottom. Did you swap the heads when you changed the cylinders from side to side? Maybe the problem is with the head and how it seals? You might also want to check the squish on each side to make sure they are the same. You should see if you could borrow a cylinder to see if that makes a difference.
 

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If the compression change doesn't follow the cylander swap I would assume it was either the crank seal on the pto side or a hole/crack in the case somewhere. What happened to the motor prior to you getting it? Did it burd down a piston or break a skirt, if it broke a skirt, it mave pushed part of it into the case half either cracking it or putting a hole in it.
 

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<div class='quotetop'>QUOTE (catspaz8 @ Jan 11 2007, 09:33 AM) <{POST_SNAPBACK}></div>
If the compression change doesn't follow the cylander swap I would assume it was either the crank seal on the pto side or a hole/crack in the case somewhere. What happened to the motor prior to you getting it? Did it burd down a piston or break a skirt, if it broke a skirt, it mave pushed part of it into the case half either cracking it or putting a hole in it.[/b]
To help minimize further confusion. . . the problem followed the cylinder from side to side according to the original poster.
 

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Discussion Starter · #12 ·
that is correct that the bad cylinder was on the mag side and had low compression and when we put another set of new rings in we switched the mag cylinder to the pto side and it still only had 65 pounds of compression, which was the exact same that it had when it was on the mag side of the case
 
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