Water-cooled Cylinder Head for Toyan Single Cylinder Engine Replace

I required this cylinder to convert an air cooled version of an FS-100 engine into a water cooled unit. Unfortunately the story had an inauspicious beginning. I in fact ordered the water cooled version of the FS-100 engine but an air cooled version arrived without explanation. Inquiries to DIY yielded no satisfaction beyond an offer of a 12% discount on future purchases. I found this water cooled FS 100 conversion cylinder on Stirlingkit's website and immediately purchased one. The cylinder arrived in a timely fashion. As an engineer, material selection and machining quality are particularly important attributes. I was very pleased to see that this cylinder was exemplary on both counts. As a tribute to machining tolerances, the cylinder liner fit appropriately and the bolt patterns were perfect. Great interchangeability. My only issue was a situation wherein the cylinder head cap screw would not fully tighten due to insufficient thread depth. I obtained an M3 bottoming tap and quickly resolved the issue. Exchanging cylinders provided an opportunity to examine the engine at the most fundamental level. Not disappointed. CNC machining quality was very high and the wrought alloy selection (probably 6061 alloy) was appropriate. A 5XXX series aluminum alloy such as 5052 may provide addition corrosion protection for the water cooled version but materials were excellent. Given the innate quality of the engine, the factory use of stainless steel cap screws would be very desirable.18-8 or 304 alloy fasteners are not that costly and accents the black anodized engine rather nicely, as I made this substitution. Design is outstanding. I particularly like the double ball bearing support solution of the crankshaft in lieu of cantilevering it off of a single or closely spaced double bearings. This design allows access to the connecting rod large end bearing as if the crankshaft was of a cantilever design. Great solution!

It would have been nice if DYI sent me a conversion cylinder at the outset. That didn't happen. Through Stirlingkit's cylinder, however, I was able to obtain a fix.
The engines impressed me to the extent that I ordered an NR 200 twin cylinder version, and will order a Cison FL4-175 when funds allow. Although there may be an intercompany connect, I will order this from Stirlingkit and not those other people.