I've got a saw to install it on now, so it's time for the details of the prototype BB Kit I have here. Bore size is 54mm resulting in a displacement of 85cc, up from 79cc stock. So far I've visually inspected, measured specs, and taken pictures. I've not yet put the parts on my saw. That will come soon enough. The P&C look very good. I intend for this is to be a fair honest report. Please keep this thread clean and on topic as I would like for it to be something of a product review than can be useful to others.
Here's some of the specs.
Here are some notes I've made so far.
Here's some of the specs.
- Piston Weight = 2.8 oz
- Wrist Pin Weight = 0.6 oz
- Cylinder Weight = 20.8 oz
- Crown thickness above top ring groove = 0.130". Plenty of room for a popup.
- Ring thickness = 0.047" = 1.2mm
- Ring end-gap = 0.008"
- Piston to cylinder clearance = 0.0025"
Here are some notes I've made so far.
- There is one small knick in the cylinder wall well below the exhaust port. It's very small and will hurt nothing. The NiSi is not damaged.
- Stihl style circlips are now used and the piston is relieve likewise for removal. A nice improvement the customers have called for.
- The ports are very nicely beveled.
- The NiSi coating and honing looks nice.
- The piston skirt does not even come close to freeporting the exhaust port at TDC.
- There is room for widening the ports, but not as much as with the 361 kit. Should be enough for modest gains.