So, the Stihl 056 had several variants over the years. As I recall, the plain 056 was 52mm and about 81cc's, the 056 Super was 54mm and 87cc's, the 056 Mag II was 56mm and 93cc's. The 056 Mag II had bigger bolt spacings on the case since the bore was larger, and you'd have to slot out the bolt holes to get the jug to work on older cases. Even then, you may have to machine larger reliefs on the inside of the cases as well to allow for the larger piston. An 056 Mag II cylinder will bolt on an 066 case with a little bit of clearancing, and I believe the piston will work on the 066 crank provided you use the 056 pin bearing. Now, here's a warning. The two a/m 54mm pistons I got from the Duke (which are probably made by the same company as LRB's pistons) had too much slop in the con rod region. Instead of being 14mm they were about 17mm between the "ears". I had to make a set of thrust washers to use one of those in an 056. I don't know if the 56mm slugs have the same issue, but I'd check that as soon as they show up in case they're too wide as well.
That took a couple reads but I think I do understand,
if I have 660 cases (as I do) then most of the 056 stuff is no good
except for the 056II 56mm? That's actually
precisely what I was hoping for, because I've rebuilt one of my 660's with 56mm big-bore kit but I had to go through 3 kits ROFL to get it just right, and the biggest(only) problem is the stupid piston they make the skirts nearly 2mm(73thou) shorter than OEM, which seems silly to me because even at the 1.610" height they come at they
do most definitely have their skirts going under the jug/into casing and the casing is way larger than 56mm there, not that that matters as I was getting my 1st kit
expecting that I
had to modify the case for fitment, was not happy/was upset finding cut skirts :/
It took 3 kits to finally get a build I like, but now you have me freaked-out about the slop between the 'ears' or "gudgeon pin bosses", I had (3) 56mm's choose from and the slop was, best to worse:
- Hyway (13.55mm), then
- Farmertec ( 14.5mm) and then
- "NewJ's" which, being installed, I cannot measure
but I remember thinking the farmertec was "midway" between the two so am guessing about ~15mm.....it did really bother me but I pictured the piston moving in its vertical-axis plane of motion and, considering even 1mm of slop
could have overhang of 1.0mm, I reasoned that it probably "aims for straightness" given the centrifugal force of the rod...
Darn now I'm all worried about this build, it's gone through heat cycling and break-in but has only done modest "extended length full-throttle" (in wood of course), will be taking the head off for piston check in several tanks will get to see then (love how easy it is working on these, I use the gaskets in a disposable fashion so I don't have to fight w/ Moto on that tiny mating surface, the 56mm jugs come with 54mm sized chambers and on the NewJ's one the exhaust floor was a good 60thou higher than OEM so it allowed me to drop it 10thou while still having 50 of before-freeport, got to flatten 1/3rd of the band and polish the rest at OEM-angle into that smaller chamber ;D
Would be curious Re "thrust washers" you used, sounds like you made them? Was close to going to Ace and just finding alum or steel washers but remembered Jennings & Blair both talking about different metals' expansion rates so I figured to just go with what I had...there's a good chance I'll swap over to the Hyway anyways, only reason I couldn't is because Hyway made it w/ the locator pin >3mm out of place so it'd let a ring into my upper transfer, am still kinda "back&forthing" with the (known) seller because I did accept & port it before I noticed the pin was outta place (sucks because I *did* check pin location, obviously as it's an involved build, but I must've just checked 1 side and it wasn't the outta place side!)
