Entisol
Active OPE Member
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I've got an 045 Super that's running well, but I want some more grunt to pull a 36" bar in softwood. The factory numbers are below.
Factory:
Squish .045"
Intake 72
Exhaust 106
Transfers 128
When I got the saw, I tore it down and went through everything. It had seen a lot of use, but was well cared for and in generally good condition. It needed a new piston, so I bought one from Sawzilla (Proline). The aftermarket piston is lighter and has windows, but it is about .020" shorter from wrist pin to top of piston, so port timing was almost exactly the same as factory with the aftermarket piston and base gasket removed. I took .020" off the base to get squish down to .025", removed a burr from the bottom of the intake port (that was worth 2 degrees, I might regret removing it), and widened the exhaust. I accidentally flattened the exhaust roof when widening (this port is deceiving, steep exit angle), so I raised the exhaust some to round it back out. The saw was sluggish when I first reassembled, but I advanced timing as far as the slots on the stator plate would allow, and it ran better.
Proline on left, original piston on right
![IMG_6131.jpeg IMG_6131.jpeg](https://opeforum.com/data/attachments/414/414598-0259eb6c20584c42d52ed922c7e1f66f.jpg?hash=AlnrbCBYTE)
Current numbers with Proline piston, gasket delete, .020" off base, intake deburred, exhaust widened/slightly raised:
Squish .025"
Intake 77
Exhaust 104-105
Transfers 131
It does not have the grunt that I think the saw is capable of. It bogs more than I think it should, given the displacement. It is cutting around 10,000rpm.
With the aftermarket piston, the compression is not as high as I'd like. There's tons of blowdown since I haven't touched the upper transfers yet. I'm going to tear back into it, but I'm looking for some advice from you guys.
- Stick with the proline piston, or try another? I want the compression back that I lost with the aftermarket piston. The factory piston is 54mm, domed, with 13mm wrist pin. Another member mentioned a 288 piston might work.
- Regardless, I'm thinking about taking another .020" off the base. This would allow me to cut squish and reduce the size of the combustion chamber, even if I use the same piston.
-Where would you go with the upper transfers? I want this saw to pull hard in a good usable range, high RPM is not the goal
-What about the exhaust? When I take it back apart, I'll make sure the exhaust is as wide as the piston will allow. I'm hesitant to raise the exhaust (even if I take more off the base) because I want torque/compression, and it already revs ~13,000k unloaded.
I'm interested in your thoughts! There's a lot of smart guys in this forum. I'll try to post a video of the saw running. Have a good one!
Factory:
Squish .045"
Intake 72
Exhaust 106
Transfers 128
When I got the saw, I tore it down and went through everything. It had seen a lot of use, but was well cared for and in generally good condition. It needed a new piston, so I bought one from Sawzilla (Proline). The aftermarket piston is lighter and has windows, but it is about .020" shorter from wrist pin to top of piston, so port timing was almost exactly the same as factory with the aftermarket piston and base gasket removed. I took .020" off the base to get squish down to .025", removed a burr from the bottom of the intake port (that was worth 2 degrees, I might regret removing it), and widened the exhaust. I accidentally flattened the exhaust roof when widening (this port is deceiving, steep exit angle), so I raised the exhaust some to round it back out. The saw was sluggish when I first reassembled, but I advanced timing as far as the slots on the stator plate would allow, and it ran better.
Proline on left, original piston on right
![IMG_6131.jpeg IMG_6131.jpeg](https://opeforum.com/data/attachments/414/414598-0259eb6c20584c42d52ed922c7e1f66f.jpg?hash=AlnrbCBYTE)
Current numbers with Proline piston, gasket delete, .020" off base, intake deburred, exhaust widened/slightly raised:
Squish .025"
Intake 77
Exhaust 104-105
Transfers 131
It does not have the grunt that I think the saw is capable of. It bogs more than I think it should, given the displacement. It is cutting around 10,000rpm.
With the aftermarket piston, the compression is not as high as I'd like. There's tons of blowdown since I haven't touched the upper transfers yet. I'm going to tear back into it, but I'm looking for some advice from you guys.
- Stick with the proline piston, or try another? I want the compression back that I lost with the aftermarket piston. The factory piston is 54mm, domed, with 13mm wrist pin. Another member mentioned a 288 piston might work.
- Regardless, I'm thinking about taking another .020" off the base. This would allow me to cut squish and reduce the size of the combustion chamber, even if I use the same piston.
-Where would you go with the upper transfers? I want this saw to pull hard in a good usable range, high RPM is not the goal
-What about the exhaust? When I take it back apart, I'll make sure the exhaust is as wide as the piston will allow. I'm hesitant to raise the exhaust (even if I take more off the base) because I want torque/compression, and it already revs ~13,000k unloaded.
I'm interested in your thoughts! There's a lot of smart guys in this forum. I'll try to post a video of the saw running. Have a good one!
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