- Joined
- Feb 17, 2009
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First... I am in no way affiliated with Northwoods Saw nor is this build test sponsored or solicitated by them. This is simply my own test of these brand new and first ever aftermarket pistons offered by anyone for these saws. I want thank Northwoods for stepping up and producing these. I did not actually buy this piston from them but from an ebayer who was selling them and had got them from Northwoods. It wasn't until after I had bought it that it became clear where it had originated from. I will be trying to show the good with the bad and venturing my own honest opinions about this build. I am not a Jonsereds tech nor a factory trained tech of any brand. I'm just a hack that has built a few 49sp saws and other Jonsereds/Jonsered saws as well..so now we all know what I'm not......LOL!!
I recieved the piston and immediately compared it to a stock one I had that was in good condition....it was very nice looking, with the correct crown as per the original. It measured perfectly to the stock "A" size code that I had. This was all good but then I measured the amount of sideplay between the wristpin bosses of the small end of the con rod.......this measured 0.128"....so I measured the stock one...0.038"...then I measured a 52/52E...0.012"...the 52 uses a wider wristpin bearing and thrust washers to control sideplay. I also measured a number of other Swede pro saws and found that most maintained between 0.008" and 0.018" sideplay. The sideplay of the conrod upper bearing dictates the sideplay of the big end bearing as well. I contacted Northwoods about this issue and they said they would work on this on future production runs. As my measurements showed the 49sp was a sloppy fit stock compared to other saws of the same brand but this piston sideplay was three times as sloppy. I thought this was way to much sideplay so I machined about 0.015" off each boss so as to fit the 52/52E wristpin bearing and thrust washers which left me with a running clearance of around 0.012". This should keep the conrod centered nicely on the crankpin.
The first pic (015) shows the piston fitted with the 52/52E thrust washers. The others are just different shots of the piston fitted to an old crankshaft.
I recieved the piston and immediately compared it to a stock one I had that was in good condition....it was very nice looking, with the correct crown as per the original. It measured perfectly to the stock "A" size code that I had. This was all good but then I measured the amount of sideplay between the wristpin bosses of the small end of the con rod.......this measured 0.128"....so I measured the stock one...0.038"...then I measured a 52/52E...0.012"...the 52 uses a wider wristpin bearing and thrust washers to control sideplay. I also measured a number of other Swede pro saws and found that most maintained between 0.008" and 0.018" sideplay. The sideplay of the conrod upper bearing dictates the sideplay of the big end bearing as well. I contacted Northwoods about this issue and they said they would work on this on future production runs. As my measurements showed the 49sp was a sloppy fit stock compared to other saws of the same brand but this piston sideplay was three times as sloppy. I thought this was way to much sideplay so I machined about 0.015" off each boss so as to fit the 52/52E wristpin bearing and thrust washers which left me with a running clearance of around 0.012". This should keep the conrod centered nicely on the crankpin.
The first pic (015) shows the piston fitted with the 52/52E thrust washers. The others are just different shots of the piston fitted to an old crankshaft.
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