266XP Cylinder

[srcarr52]

272 cyl on 266

Good news. No case modification necessary.

Here is a 272 cylinder, manifold and carb sitting on a 266 case.
View attachment 142065
View attachment 142066

Notice the boot for the idle adjust is getting very close to the bolt location for the top cover. The mixture screw window in the case is in the same location.

The manifolds are completely different so a 272 manifold plus hardware is a must (272 carbs mount with screws that go through the hole assembly of the boot, carb and manifold).

The carbs are very similar on the outside but differ in bore size 0.796" for the 266 and 0.810" for the 272. So you'll want to change to a 272 carb but you may want to modify to 266 throttle shaft to fit into the 272 carb to keep the in case idle adjustment. Here are the carbs, 266 on the left.
View attachment 142067
View attachment 142068

All of this should fit under the 266 cover. You could convert to a 272, 268, or late 61 cylinder cover but the bolt pattern is different for the left side of the saw. The screw by the muffler has more then enough meat in the case to drill and tap the new screw but the rear only has 1/8" of material before open air of the carb box.

 

[srcarr52]

266 vs. 272

I remember reading on AS that older 61, 66's and maybe 266 had finger ports. But looking at the one I have the ports are closed like that of a 268, 272 but the piston design is much different. Here you'll see the 266 piston (left) is a full circle where the 272 is only covering the ports.
View attachment 142070

Which means the classic 272 transfer port job like below wont do any good.
View attachment 142072

Exhaust is the same.
View attachment 142073

Intakes are way different.
View attachment 142074

 

[TRI955]

Got the replacement cylinder today from Moss Man, this thing looks great!!! I don't think I'm going to even change the ring. Thanks again!

 

[SawTroll]

Threads about this "family" of saws tend to leave about as many questions open, as they answer, and it looks like this one will as well. A lot of changes happened, without always being reflected with new model numbers/designations.

 

[Cantdog]

Threads about this "family" of saws tend to leave about as many questions open, as they answer, and it looks like this one will as well. A lot of changes happened, without always being reflected with new model numbers/designations.

Kinda missed you on this discussion Niko. Was hoping you would have a bit more insight on this subject than me. I only know about what I have personally owned and built but not so much about models that I haven't. Glad you got your computer straightened out and are back online with us.

Glad you got your P&C for your 266Xp too. TRI955 Good luck with it.

 

[TRI955]

The 266 is back together and running well....very well! I see why the guys that have run these talk so highly of them. It feels very good in the hands and has all kinds of power. Feels like the power of a much bigger saw. I will try to make a video of it in the next few days in the same Sycamore that I ran my ported 372xp in, the 266 just might suprise me!

 

[Moss Man]

I'm glad to see that this all worked out, the 66cc class saws are my favorites.
I hoard up OEM cylinders new and old, I think they are worth a little extra expense.

A video would be nice!

 

[SawTroll]

....

My SE came with a closed transfer setup but, as it was said earlier, you never know who got there before you, and maybe some of them were indeed closed transfer from stock.

Yes, that is the problem in a nut-shell - you never know how these old saws were when they left the factory - lots of "frankensaws" and unoriginal (mostly newer) parts out there.......

There sure was a difference (also in specs) between the early 266SEs and late 266XPs, but afaik it has proven impossible to find out when they changed, and the exact reason, even with lots of IPLs availiable.

 

[TRI955]

Not too sure what year the SE was, but it was the same as the XP that I pulled apart. I did a compression test on the saw last night, it sits at just over 190psi.....

 

[Moss Man]

Not too sure what year the SE was, but it was the same as the XP that I pulled apart. I did a compression test on the saw last night, it sits at just over 190psi.....

The SE I pulled it off from was a 1985 model, that's not to say that everything was original though.

190lbs compression? Did you leave the base gasket out?

 

[TRI955]

The SE I pulled it off from was a 1985 model, that's not to say that everything was original though.

190lbs compression? Did you leave the base gasket out?

I'll check the year of my XP tonight. I did use a gasket, just about .007" thinner than the stock one.

 

[blsnelling]

Have you compared your guage to another known good one, or on another good condition stock saw? That does just sound out of the ball park high. I wouldn't expect it to be that high with a .030" popup.

 

[TRI955]

The gauge is only a few months old.....

 

[blsnelling]

The gauge is only a few months old.....

But still. Your 288 compression sounded too high too. Stock compression on a Husky is rearly higher than 160. A popup only nets you maybe 20 PSI. BTW, I'm not knocking your work or saws at all. I'm just questioning your guage. That's all

 

[TRI955]

I guess I'll take a new gauge home with me tonight and test it out.

 

[blsnelling]

I guess I'll take a new gauge home with me tonight and test it out.

Do you have a stock saw you could test yours on?

 

[srcarr52]

272's end up being 160-170 psi with the base gasket removed. I don't know how a stock 266 would be above there.

 

[TRI955]

Do you have a stock saw you could test yours on?

Not really...I have a new gauge sitting here next to me, I'll do some back to back comparisons tonight when I get home and post the results. If all is good with my old gauge, I will have a like new Lisle 20250 compression tester for sale...

I do have the 262xp, I have always assumed it was stock.

 

[blsnelling]

I do have the 262xp, I have always assumed it was stock.

What does it pull on your guage? I might add that my Lisle was way off when I got it. I had to pull the needle and put it back on to calibrate it with my compressor guages. I'm not using a SnapOn guage. I got tired of quesitoning my results.

 

[TRI955]

So, I used my old original, the old Lisle and the new Lisle compression testers, pulled on the 266 till the needle quit raising and this was the results

Old Sunpro 192psi
Old Lisle 200psi
New Lisle 200psi

Do you think they are all off that much???

Here's a video of the 266xp in the same piece of Sycamore that I tested the 372 in...

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Here's the 372 for comparison....

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