Pioneer P51 piston

Rugged made
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p61 western said:
I'm thinking they sent you the wrong piston.I looked at the ipl's for the 50,51 and the 52,and the piston pin and bearings are all the same part number.I bought rings for a p-51 that fit my p-52 just fine.Little red barn has a listing for a p-52 piston that should work for you.Heck if ya had the parts you could put a p-60 or p-61 top end on it.
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P61 Western, I also looked on rotman sales and the illustrated parts list for the P52 shows the same part numbes as the P51. I tried emailing lilredbarn to see if they would do a swap for the P52 piston but I have not heard back yet. I have not yet started the breakdown of the P51 so I can't check the crank yet. The NOS crank shows part #475422 which the illustrated parts list shows. You would not happen to know the P51 wristpin diameter would you? The P50 piston that I bought has a wristpin diameter of 12.69mm with a caliper.
 
p61 western said:
Just a thought maybe the nos crank isn't for that saw.Might want to take the cylinder off your saw and see if the piston you got fits that crank.Just would suck to buy another piston you might not need.
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I got to looking at the NOS crank and can not find a part # on it. The part #475422 is on the bag it is in but I can't find a part # on the crank itself. the connecting rod shows #433455
 
p61 western said:
Just a thought maybe the nos crank isn't for that saw.Might want to take the cylinder off your saw and see if the piston you got fits that crank.Just would suck to buy another piston you might not need.
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P61 western, I looked at the NOS crank that I have and the bag it is in is marked part #475422 which is what the illustrated parts list shows. I can't find a part # on the crank itself but the Connecting rod has #433455 embossed on it. I have not yet had time to start tearing the saw down so I can't check to make sure the NOS crank is the right thing. Do you know if the conn rod # is right?
 
I don't know the wristpin measurements of them.The ipl's I have seen don't list the rod part numbers.I have a 4 cube crank out and the rod number doesn't match yours so that is a good thing.I just had my p-52 apart but didn't pay attention to the rod part numbers.At this point it would be best to pull the cylinder off your p-51 and check it that way so you know for sure.I wish i had a better answer but I don't.
 
p61 western said:
I don't know the wristpin measurements of them.The ipl's I have seen don't list the rod part numbers.I have a 4 cube crank out and the rod number doesn't match yours so that is a good thing.I just had my p-52 apart but didn't pay attention to the rod part numbers.At this point it would be best to pull the cylinder off your p-51 and check it that way so you know for sure.I wish i had a better answer but I don't.
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I will try to get some time this week to take the cylinder off so I can compare crankshafts and piston wristpins. I need to buy a case splitter off ebay to take the case halves apart. Last time I tried to do it without the right tools I cracked the case half on an old Stihl parts saw. I watched some vids on the crankcase splitters sold on Ebay and think that would be the best route to go. I will try and get some pics of the saw before I tear it down and of the parts after the tear down. Thanks for the help so far though.
 
Would love to see some pics of your saw.It is probably a good idea to get a case splitting tool.I have done it very carefully without but would be nice to have the tool.I did not mention it but my 4 cube crank does not have any part numbers on it.
 
OK everybody who has been helping me out here, I tore the saw down as far as I could this morning and compared the P50 Piston kit from Lilredbarn to the original piston. The piston pin and piston diameter are the same as the original. the only difference is the new piston has thicker rings than the original. I don't know if this would cause any problems or not. Would this be an issue? Also, the NOS Crankshaft I have is not the same. The wristpin and bearing are smaller on the NOS than the saws original crank. Everything looks very close the the saws original crank but the wristpin size is definatley bigger than the NOS crank. If anybody has a NOS crank, Part #475422, I would be interested in buying it or possibly trading for a NOS MAHLE P42 cylinder I found. The part # is 433261 and it is made in USA. I found the part number on line and it shows for a Pioneer P42. If I can't find a NOS crank, I will replace the crank bearings and wristpin bearing and put the lilredbarn p50 piston in it.
 
OK, Don't know what happened there but it doubled some of the pictures, sorry. the last three pics were after I pressure washed it and a lot of paint came off the case.
 
Bubba Stump said:
OK everybody who has been helping me out here, I tore the saw down as far as I could this morning and compared the P50 Piston kit from Lilredbarn to the original piston. The piston pin and piston diameter are the same as the original. the only difference is the new piston has thicker rings than the original. I don't know if this would cause any problems or not. Would this be an issue? Also, the NOS Crankshaft I have is not the same. The wristpin and bearing are smaller on the NOS than the saws original crank. Everything looks very close the the saws original crank but the wristpin size is definatley bigger than the NOS crank. If anybody has a NOS crank, Part #475422, I would be interested in buying it or possibly trading for a NOS MAHLE P42 cylinder I found. The part # is 433261 and it is made in USA. I found the part number on line and it shows for a Pioneer P42. If I can't find a NOS crank, I will replace the crank bearings and wristpin bearing and put the lilredbarn p50 piston in it.
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The thick rings should be fine,but if you want thin you could get the p-52 piston.Some say that thick rings will wear a cylinder out faster than the thin rings.And some say thin rings are better performance.Could be a Ford vs chevy thing.I'm not sure how to tell, but you might have a nos p-42 crank and cylinder that I maybe interested in if nobody come's up with a nos p-51 crank.
 
 
I got to tearing things down more and found the air filter cover was only held on by the screw up front, the rear nub that goes into the throttle area is broke off. I originally wanted to stay all original but decided to do some upgrades on the saw. I will do some polishing work on the case intake port and my brother has volunteered to mill an aluminum reed valve block that will have a bigger port than the original plastic reed block. I found another old muffler in a parts bucket in my grandmas barn and will try and use it to make the original muffler dual ported. I wanted my brother to mill a velocity stack intake but decided to try and find a top mount donut style air filter assembly off of a old cut off/concrete saw. I think it will make the saw look like one of the high performance P-Series saws. If anybody has the whole assembly or an old Target Quickie saw with the assembly in good shape let me know. I would be willing to buy or trade for it. Also, does anybody know what it would cost to have my P51 powder coated with the original yellow/green and dark green color scheme? Also, If anybody knows of any other upgrades that would make this saw better, I am all ears.
 
OK here is a little bit of an update on the P51. I received most of the parts I had ordered today including a Husqvarna/Stihl case splitter. The splitter does not quite fit the Pioneer P-series saws but I was able to bend the end to make it fit over the crank. You can push out the starter fan side but the clutch side is to long for the tool. I found a deep socket that fit over the splined end of the crank and poped it out of that side of the case with a dead head hammer. other than that the tool worked great. I also had ordered another piston because the P50 piston I got off of lilredbarn.com was to tight and I did not like the end gap of the piston rings. Also, the rings on the lilredbarn piston were thick and I wanted the thin rings. I found a NOS Poulan Pro 525 piston and it ended up fitting perfect. I kept the lilredbarn piston and will use the new piston pin and retainer clips off it to put on the 525 piston. My NOS p51 rings fit the 525 piston perfect also. I also got the NOS crank bearings in but have not installed them yet. Does anybody have any tricks to getting the old bearings off?
 
watched some youtube vids to see about getting the crank bearings off. Most of the vids showed the bearings staying in the case halves so they did not have to take them off the crank, they were using the case splitter. My bearings stayed on the crank and I ended up retrofitting a valve spring compressor to use as a puller. It was a little awkward but it got the bearings off without any damage. I think I will stick the crank in the freezer for a day and then heat the bearings in the oven for a few minutes to install them on the crank. There was a vid of that and it looked like it worked good. The saw is completely disassembled and ready to prep for paint or powdercoat. I might buy a small plast cabinet and bead blast all the mag parts but that will be down the road. I don't have a compressor big enough to handle a blast cabinet so I will have to save some money for now so I can get one. Everybody have a good labor day weekend and stay safe.
 
Hello all, I found the paint code for the yellow green pioneer p-series saws on the sticky's but I never did find the code for the dark hunter green paint. Does anybody know what it might be?
 
Bubba Stump said:
OK here is a little bit of an update on the P51. I received most of the parts I had ordered today including a Husqvarna/Stihl case splitter. The splitter does not quite fit the Pioneer P-series saws but I was able to bend the end to make it fit over the crank. You can push out the starter fan side but the clutch side is to long for the tool. I found a deep socket that fit over the splined end of the crank and poped it out of that side of the case with a dead head hammer. other than that the tool worked great. I also had ordered another piston because the P50 piston I got off of lilredbarn.com was to tight and I did not like the end gap of the piston rings. Also, the rings on the lilredbarn piston were thick and I wanted the thin rings. I found a NOS Poulan Pro 525 piston and it ended up fitting perfect. I kept the lilredbarn piston and will use the new piston pin and retainer clips off it to put on the 525 piston. My NOS p51 rings fit the 525 piston perfect also. I also got the NOS crank bearings in but have not installed them yet. Does anybody have any tricks to getting the old bearings off?
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Can you explain where the bearings are? Do you mean they are still on the crank? There are easy ways to handle the bearing removal and install but more info from you needed.
 
pioneerguy600 said:
Can you explain where the bearings are? Do you mean they are still on the crank? There are easy ways to handle the bearing removal and install but more info from you needed.
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I am talking about the bearings on either side of the flywheel, the ball bearings, they stayed on the crank when I split the case halves. the connecting rod bearings take some special tooling to remove and install so I will not mess with them. the rod bearings are in good shape. I ended up modifying a valve spring compressor and got the crank bearings off without incident or damage. I watched some videos on Youtube and will freeze the crank in the freezer and heat the bearings in the oven to install the new ones.
 

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