T
theshadowrider
Well-known member
Okay,
After the numerous threads about the IQ motors and the problems associated with them it got me thinking about my own motor and its sustainability. I put a turbo on my dragon the start of the 2010 season at 1000 miles and have loved every minute of it. I current have 1700 miles on it. I had the top-end replaced under warranty at 700 miles, for the "update" so I have ruffly 1000 miles on this top end which 700 are boosted. Before I put the turbo on, I had a 1000 miles on the sled, so I had 300 miles on the pistons since the update. When I installed the turbo, I noticed that one side of the pistons already had the coating wearing off. I have now decided to put a new top end in and in the process have discovered some very interesting things that has confirmed what others have been saying. This season I was nervous throughout the year because of the abnormal wear that I saw at 300 miles on the top end. I just keep reading about piston slap, broken skirts, and piston clearance. So I decided to try determine what my piston clearance is. I have read many talking about how loose these pistons are and how they are not even within specs. So here is what I have come up with to confirm others findings
First off, I have asked around and talked to many different people on the best way to measure piston to wall clearances. Some have told me about using feelers gauges, others using calipers, but I what I thought, and was told would be the most accurate was using a digital micrometer accurate out to .0000 and these handy machinist tools, so that is what I used. I also decide there are many different variables involved so I tried to eliminated as many as I could and take dozens of readings then average them out.
This is what I used to measure the piston clearance. First I measured the piston, as per the manual by taking the micrometer and measuring 3/8" from the skirt 90 degrees to the pin. I took a dozen reading on each piston and this is what I came up with.
Stock Piston
Left Side: 3.3373" Right Side: 3.3366"
Stock Piston don't measure the same and the wear confirms it!
Stock pistons with left piston in picture pto side, right piston mag side.
Right piston (Mag) intake side
Left piston (PTO) intake side
Right piston (Mag) exhaust side
Left piston (Pto) exhaust side
I took 12 readings on each side of the cylinders and then averaged them to come up with this. I used the machinist tool to mark the piston width and then used the micrometer to measure.
Left cylinder measurements: 3.34617"
Right cylinder measurements: 3.34605"
Now do the math and I get a piston to wall clearance of
Left Side: .00887"
Right Side: .00945"
According to Polaris for a 2008 800 rmk dragon, looking in my service manual it calls for the piston to wall clearance to be: .0037" - .0053"
So next I measured my new wiescos that I am putting in and this is what I came up with. Note: Cylinder, and all pistons sat overnight in shop to make sure all surfaces where the exact same temp when measuring.
After numerous measurements and averaging them I cam up with.
Left piston: 3.3417"
Right Piston: 3.3416"
Now I realize when you get out to .0001" there is a degree of measurement error.
Now doing the math from the cylinder specs from above, this is the clearance I come up with the wiscoes.
Left Side: .00447"
Right Side: .00445"
With in service limits now of .0037" - .0053".
Now will have to wait until next season to see how they hold up compared to oem stock, but betting on these measurements they are going to be better than stock!
After the numerous threads about the IQ motors and the problems associated with them it got me thinking about my own motor and its sustainability. I put a turbo on my dragon the start of the 2010 season at 1000 miles and have loved every minute of it. I current have 1700 miles on it. I had the top-end replaced under warranty at 700 miles, for the "update" so I have ruffly 1000 miles on this top end which 700 are boosted. Before I put the turbo on, I had a 1000 miles on the sled, so I had 300 miles on the pistons since the update. When I installed the turbo, I noticed that one side of the pistons already had the coating wearing off. I have now decided to put a new top end in and in the process have discovered some very interesting things that has confirmed what others have been saying. This season I was nervous throughout the year because of the abnormal wear that I saw at 300 miles on the top end. I just keep reading about piston slap, broken skirts, and piston clearance. So I decided to try determine what my piston clearance is. I have read many talking about how loose these pistons are and how they are not even within specs. So here is what I have come up with to confirm others findings
First off, I have asked around and talked to many different people on the best way to measure piston to wall clearances. Some have told me about using feelers gauges, others using calipers, but I what I thought, and was told would be the most accurate was using a digital micrometer accurate out to .0000 and these handy machinist tools, so that is what I used. I also decide there are many different variables involved so I tried to eliminated as many as I could and take dozens of readings then average them out.
This is what I used to measure the piston clearance. First I measured the piston, as per the manual by taking the micrometer and measuring 3/8" from the skirt 90 degrees to the pin. I took a dozen reading on each piston and this is what I came up with.
Stock Piston
Left Side: 3.3373" Right Side: 3.3366"
Stock Piston don't measure the same and the wear confirms it!
Stock pistons with left piston in picture pto side, right piston mag side.
Right piston (Mag) intake side
Left piston (PTO) intake side
Right piston (Mag) exhaust side
Left piston (Pto) exhaust side
I took 12 readings on each side of the cylinders and then averaged them to come up with this. I used the machinist tool to mark the piston width and then used the micrometer to measure.
Left cylinder measurements: 3.34617"
Right cylinder measurements: 3.34605"
Now do the math and I get a piston to wall clearance of
Left Side: .00887"
Right Side: .00945"
According to Polaris for a 2008 800 rmk dragon, looking in my service manual it calls for the piston to wall clearance to be: .0037" - .0053"
So next I measured my new wiescos that I am putting in and this is what I came up with. Note: Cylinder, and all pistons sat overnight in shop to make sure all surfaces where the exact same temp when measuring.
After numerous measurements and averaging them I cam up with.
Left piston: 3.3417"
Right Piston: 3.3416"
Now I realize when you get out to .0001" there is a degree of measurement error.
Now doing the math from the cylinder specs from above, this is the clearance I come up with the wiscoes.
Left Side: .00447"
Right Side: .00445"
With in service limits now of .0037" - .0053".
Now will have to wait until next season to see how they hold up compared to oem stock, but betting on these measurements they are going to be better than stock!
Last edited:
