Yes, you read that right. I have setting on my desk here a brand new prototype MS361 BB kit. Bore size is 49mm resulting in a displacement of 64.1cc, up from 59.0 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 = 2.4 oz
- Wrist Pin Weight = 0.4 oz
- Cylinder Weight = 16.4 oz
- Crown thickness above top ring groove = 0.135". Plenty of room for a popup.
- Ring thickness = 0.047" = 1.2mm
- Ring thickness = 0.009" and 0.011"
- Piston to cylinder clearance = 0.0015".
Here are some notes I've made so far.
- If the piston is twisted perhaps 45* in the bore, it gets a little snug. The corners of the tails of the cylinder that fit into the case are 0.001" tighter than in the middle. It's a non issue when lined up as it would be when assembled. These never contact the piston during operation.
- There is one small pourous cavity in combustion chamber, a non-issue.
- 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.
- Lots of extra skirt width and meat in the ports for porting.
- The piston skirt does not even come close to freeporting the exhaust port at TDC.
