I done this tear down back in the winter,I am going to post another set of measurements that I just did with 52+ hrs.
Motor: 03 KX250 Head mod and ports altered
Boyesen Pro Series reeds
Klotz R-50 40:1
AV GAS 100LL JETTED ON THE MARK..
MX only ridden at ORV Chaddsworth, Blue Diamond, and Seaford, DE.
As some of you know, I am a big fan of Maxima 927 (castor based with synthetic). The KX250 port layout, especially on the intake side, is a little aggressive. Light vertical scratches form on the intake side of the piston below the bottom ring and in line with both ring locating pins. This is not dirt related - trust me on this. The only oil that I have seen eliminate this is the 927. The 927 is excellent at lubricating and would be my oil of choice, but the main and sub powervalves are time consuming to strip because of the hard, baked on carbon wedged between the valves and chamber. The KX's, 03 and past, do not have a breather line for the power valve chamber. This just compounds the carbon even more. YZ's and RM's would be easier to strip. Lubrication is top priority then cleanliness. If an oil keeps the valves, head, and piston ring groove fairly clean that is fine and dandy, but if lubrication is in question, what good is it? Everyone is so concerned about how clean their motor is with a certain oil, they rate that oil on cleanliness alone. I too like to have my powervalves drop right out and the head with light or no build up along with the piston, but to have both lubrication and a fairly clean motor is a great combination.
The KLOTZ R-50 line is synthetic ester (not castor based like their other oils). These are my findings.
I am not a Klotz dealer I have nothing to gain or lose from my comments. I will give measurements first, then my visual inspection. The R-50 was used exclusively after a fresh top end and also broken in with it.
Wrist pin dia: 17.99mm standard is 17.995-18mm / service is 17.96.
Ring thickness: .97mm standard is .970mm-.985 / service is.90mm.
Piston ring groove width: 1.02 standard is 1.01-1.03mm / service is 1.11mm.
Ring end gap:.51mm(.020in) standard is .35-.55mm (.014in-.0215) / service is.90mm (.0335in)
Piston dia : 66.33mm standard 66.336-66.351mm / service is 66.23mm.
Rod big end side clearance
.020in) standard (.018-.022 in) service/ is .027in.
Side clearance was .(020) Last tear down also.
As you can see the numbers look great. I could have gone another 15 hrs easily . I have it apart, so you know the deal!!!!
The main valve pulled right out there was no carbon at all wedged in between the valve and chamber. There was a smidgen of carbon at the valve end sides, not in the center portion. It was not hard at all, and I could have scraped it off with my fingernail. The valves were also very well lubricated with a nice coating of oil. In fact, the subs slid out very smoothly just as the main valve. The rest of the valve and the sub valves were just discolored (CARAMEL COLOR). I put them on my bench grinder with a very fine wire brush, PIECE OF CAKE!!! The teeth on the subs also had a nice coating of oil between them, some of the teeth did have slight carbon build up, but nothing drastic. The teeth spaces are very narrow. I am very happy with the stripping of the valves and the medium clean up. The head was just discolored. The piston had very light carbon on the crown which is normal. I did have slight blow by on both sides of the piston above the wrist pin and on the right side of the exhaust. I pulled my pipe after a few hours on the new top end and saw the slight blow by on the exhaust side. It looked the same when I tore it down 40 hours later. The face of the rings looked beautiful showing no blow by at all. I am confident in saying that I had the blow by from the break in period. The crank halves had a very good and sufficient layer of oil on them when rotating. I just loved the way this oil was being picked up. I was riding pretty hard my last ride before I shut down. I only idled in about 10 seconds, so 40:1 with the R-50 IS MORE THAN SUFFICIENT. Did I mention I like the way this oil layers the crank? The thrust washers were moving very freely and the rod itself looked like it had been getting lubricated with oil. It had kind of a rich color to it, no surface rust at all. The piston on the intake side looked great, no vertical scratches - what more can I say. As you can see I have a fetish with oils.
Motor: 03 KX250 Head mod and ports altered
Boyesen Pro Series reeds
Klotz R-50 40:1
AV GAS 100LL JETTED ON THE MARK..
MX only ridden at ORV Chaddsworth, Blue Diamond, and Seaford, DE.
As some of you know, I am a big fan of Maxima 927 (castor based with synthetic). The KX250 port layout, especially on the intake side, is a little aggressive. Light vertical scratches form on the intake side of the piston below the bottom ring and in line with both ring locating pins. This is not dirt related - trust me on this. The only oil that I have seen eliminate this is the 927. The 927 is excellent at lubricating and would be my oil of choice, but the main and sub powervalves are time consuming to strip because of the hard, baked on carbon wedged between the valves and chamber. The KX's, 03 and past, do not have a breather line for the power valve chamber. This just compounds the carbon even more. YZ's and RM's would be easier to strip. Lubrication is top priority then cleanliness. If an oil keeps the valves, head, and piston ring groove fairly clean that is fine and dandy, but if lubrication is in question, what good is it? Everyone is so concerned about how clean their motor is with a certain oil, they rate that oil on cleanliness alone. I too like to have my powervalves drop right out and the head with light or no build up along with the piston, but to have both lubrication and a fairly clean motor is a great combination.
The KLOTZ R-50 line is synthetic ester (not castor based like their other oils). These are my findings.
I am not a Klotz dealer I have nothing to gain or lose from my comments. I will give measurements first, then my visual inspection. The R-50 was used exclusively after a fresh top end and also broken in with it.
Wrist pin dia: 17.99mm standard is 17.995-18mm / service is 17.96.
Ring thickness: .97mm standard is .970mm-.985 / service is.90mm.
Piston ring groove width: 1.02 standard is 1.01-1.03mm / service is 1.11mm.
Ring end gap:.51mm(.020in) standard is .35-.55mm (.014in-.0215) / service is.90mm (.0335in)
Piston dia : 66.33mm standard 66.336-66.351mm / service is 66.23mm.
Rod big end side clearance
.020in) standard (.018-.022 in) service/ is .027in. Side clearance was .(020) Last tear down also.
As you can see the numbers look great. I could have gone another 15 hrs easily . I have it apart, so you know the deal!!!!
The main valve pulled right out there was no carbon at all wedged in between the valve and chamber. There was a smidgen of carbon at the valve end sides, not in the center portion. It was not hard at all, and I could have scraped it off with my fingernail. The valves were also very well lubricated with a nice coating of oil. In fact, the subs slid out very smoothly just as the main valve. The rest of the valve and the sub valves were just discolored (CARAMEL COLOR). I put them on my bench grinder with a very fine wire brush, PIECE OF CAKE!!! The teeth on the subs also had a nice coating of oil between them, some of the teeth did have slight carbon build up, but nothing drastic. The teeth spaces are very narrow. I am very happy with the stripping of the valves and the medium clean up. The head was just discolored. The piston had very light carbon on the crown which is normal. I did have slight blow by on both sides of the piston above the wrist pin and on the right side of the exhaust. I pulled my pipe after a few hours on the new top end and saw the slight blow by on the exhaust side. It looked the same when I tore it down 40 hours later. The face of the rings looked beautiful showing no blow by at all. I am confident in saying that I had the blow by from the break in period. The crank halves had a very good and sufficient layer of oil on them when rotating. I just loved the way this oil was being picked up. I was riding pretty hard my last ride before I shut down. I only idled in about 10 seconds, so 40:1 with the R-50 IS MORE THAN SUFFICIENT. Did I mention I like the way this oil layers the crank? The thrust washers were moving very freely and the rod itself looked like it had been getting lubricated with oil. It had kind of a rich color to it, no surface rust at all. The piston on the intake side looked great, no vertical scratches - what more can I say. As you can see I have a fetish with oils.
