Upon your experience I am going back to a 7 pin rim, and the larger CC will matter. Was the 075 jug hard to find? and will the 051 keep up?
andy
On 18" and under logs the 051 will keep up just fine. On anything biger and you start to notice the difference. That said I milled for over 10 years using my 051 and did quite a few 36" logs.
The 051/075 swap isn't quite a simple bolt on conversion. The 051 uses 5mm bolts to secure the jug and the 075 uses 6mm studs. The studs and nuts are still available from the dealer and it is pretty simple to re-tap the holes by hand.
Not to confuse you too much but there is an early and late version of the 051. the early version has two small notches in the top of the case where the jug bolts on. These notches are inline front and rear of the connecting rod and even though it dosent need them for clearance it looks like thats what they are for. The late version lacks these notches. I have a feeling that the jug of a early 075 will fit an early 051 but I know for certian that the jug off a ts760 will not fit an early 051.
When converting a late 051 using a ts760 jug you will also need a muffler and phenolic intake block off a 076. The parts off a ts760 will work also but the muffler on a ts760 lacks a spark arrester.
I own an early 051 and a late 051. For my conversion I used the late model 051 and a NOS jug off a ts760. I picked up a trashed ts760 on ebay for the muffler and intake block. all told The swap cast me about $250 with all the shipping and gaskets and studs from the dealer. Was it worth it? well The saw I converted was pretty minty 051 I paid $300 for and now I have a minty 075 with fresh P&C for $550. a fair price but not a screaming deal.
Beware of buying any ts760 used parts. A lot of those saws were thrashed and end up full of concrete dust.
The 051/075/076/ts760 all use the same carb. There are some different letter suffexes on the Tillotson HS series but the will all work just fine.
I almost forgot, burried in that $250 cost was the cost of a decompression valve. neither of my 051's had one and while they would kick me once in a while I never really needed one. With the extra 22cc and as-new-compression you need the dcomp valve!