Stihl cylinder identity help????????

Ok I won this on ebay a few days back and it came in today...Used Stihl 066 cylinder and piston.Looks way better in person then in any pic's..Anyway I was thinking about putting this on a 064 crank case so I'm thinking I will have to at least slot the holes and maybe open the case for the skirt right??

So first I set to looking over the new parts and I noticed that the holes for the head bolts look a little bigger then they should.. I place a 064 head gasket on it and the holes line up perfect. So I'm thinking sweet.. I then place the piston on the crank and rotate it to the bottom where I find there seems to be plenty of room for the piston..Now I'm like something is wrong no way this was on a 064 and my 064 case just happens to have enough room with no grinding. Can't be I don't get that lucky...The piston is 54mm and there is the decomp hole that tells me it's not 064..

Some pic's of the markings on the cylinder..





064 cylinder on the left.....


Dry run no rings..





So is this a 066 cylinder that was fit to a 064 and I just got lucky???

Thanks..............

Apparently some of the later 064s that were made for the Canadian market had spacing on the cylinder bolt holes that was the same as 066. This was all hashed out a few years ago. Stihl never issued a technical bulletin on it, so mark it up to being an "undocumented production line change."

Yup, I'd say you got lucky.

Sweet!!!!!!

Thanks again Jacob J......

Now anyone have the part number for a 066 flat top cover with the decomp hole????

If you need one of those nice plastic flywheels for that saw, let me know as I just acquired one for $1 (.99c really but who's counting ) and I'd sell it very cheap or trade it if you need it. I don't even own a 064/66 but I just couldn't resist the bargain price.

Jimbo

Thanks but I think I would need a newer coil and and new starter assembly to accommodate it....

The plastic/polymer flywheel won't fit the 064 crank. The later 066/660 cranks that use the polymer flywheel are proprietary.

Ok I don't know if I can word this right but here goes...

I know that the newer 066 and the 660 have a shroud or top cover that has a curve to it and the older one don't...Is there a reason for it?? Does it have to do with the shape of the head??

If so How can I tell the one I need?? I don't want to buy a flat one and it not fit..

Thanks.......

southbound said:

Ok I don't know if I can word this right but here goes...

I know that the newer 066 and the 660 have a shroud or top cover that has a curve to it and the older one don't...Is there a reason for it?? Does it have to do with the shape of the head??

If so How can I tell the one I need?? I don't want to buy a flat one and it not fit..

Thanks.......

Click to expand...

where's jacob when you need him?

if you have a metal flywheel i'd bet you need the flat top.

It's going on a 064 so it has a metal flywheel....

I have no idea what the saw the 066 cylinder came from had....

southbound said:

Ok I don't know if I can word this right but here goes...

I know that the newer 066 and the 660 have a shroud or top cover that has a curve to it and the older one don't...Is there a reason for it?? Does it have to do with the shape of the head??

If so How can I tell the one I need?? I don't want to buy a flat one and it not fit..

Thanks.......

Click to expand...

Are you building an 064 or an 066?

The rounded top cover was proprietary to the later 066 and MS-660 saws that use the polymer flywheel. It matches the newer starter, as seen here: New style 066/660 starter

If you're building an 064, then you need a flat-top 064 top cover. The flat-top early 066 top cover and 064 top cover are different and are not interchangeable.

Building a 064 with a 066 cylinder...

I was wanting to keep the the narrow starter..

So how does everyone feel about a exposed decompression valve????

You'd either have to block-off the compression release hole with a plug (which is what I'd do) or cut a custom hole in your top cover.

If you want to stick with the narrow 064 starter then you need the flat 064 top cover.

However, you can use the rounded later 066/MS-660 top cover if you want, it just won't line up perfectly with your 064 starter (the top cover will stick out over the top of the starter about 1/4".)

First off let me say I fell dumb for over looking the width issue with the starter assembly's...

Second Thanks for all your help!!!!

I do a lot with Kydex and I am sure I will be able to come up with a shroud for the decomp valve...

I still have to come up with a spacer for the 066 hand guard the dealer ordered me...

As far as the spacer goes, just use another of the same bushing that's in the handguard already where it bolts on over the starter:

1124 792 5505 grommet
1124 792 5500 bushing

Stacking those two bushings works fine.

southbound said:

I do a lot with Kydex and I am sure I will be able to come up with a shroud for the decomp valve...

Click to expand...

Aircraft Interior?

Jimbo