Stihl and husky rebuild help / advice wanted

[Country bumpkin]

Hello all you fine , knowledgeable people , this is my first time on board here and am looking for some help . I recently acquired a Stihl MS271 and a Husky 555 xtorq , both partially disassembled with tore up cylinders . I have no idea the history of the saws . Initial thoughts were straight gas , both tanks have pre-mix (now anyways , maybe added after the fact ?) . With most things involving internal combustion , I prefer to sway towards performance and am trying to figure out if I will rebuild either one or both of these saws and if they would stay in their original configuration or aim for the " bigger,better " direction . Being completely honest , chainsaws are not 100% my thing , my experience with them is limited , certainly compared to most on this forum (which is why I'm here) . I've spent a number of hours now trying to search out part numbers to see what options I would have available and am not having much luck . My main question is displacement , are these engines part of a family / design that share la arger bore ? IE , can I put a MS291 jug on the 271 ? As far as I can tell they have the same exhaust , carb and crank .

Even though I dont use saws alot , I have it in my head since I got these and have been doing some reading that I want a professional series saw . I am being told by people that both of these saws are not professional series and being told by others that they are in the bottom end of the professional class .

I also wouldn't mind doing some porting during the rebuild (if it is to happen) , I have some porting tools but again , not alot of experience (just on my snowmobiles ) . Is there any good resources out there for porting chainsaws , I know they share the same principle as any other 2 stroke engine , I just dont know the math / science behind it . I can figure out port heights and duration with no issue , determining the changes to make is where I'm left scratching my head .

I appreciate any and all input .

Yes a 291 cylinder & piston will work with no issues & carb & setting the same.

 

[MountainHigh]

re: Does anyone see any issue with my plan ?

well that kind of conversion of a 555 into a 562 is well beyond my skill set.

I would think for the perhaps complicated, yet modest power increase from a 555 to a 562, you might be better off muffler modding and porting the 555 - some prefer the slightly lighter 555 small mount bar setup as it resembles the Euro husky 560 in that regard.

 

[gasax]

More good information , thank you !!

 

[weimedog]

562 cylinder is essentially the same as a 555. the crank is different though. The 555 is wider by the distance of the two sheet metal cages that hold the stuffers it's really matching the crank with the stuffers with the 562 el48 and ignition. So think of it as a three part deal. Crank carb ignition. It's probably ok to mix a 555 non stuffer crank with the 562's el48. Just that's a lot of stuff. A stock 555 with a compression hike and a muffler mod is what I would do.

 

[Country bumpkin]

Do a search on cleaning up cylinders. I've done 3 271/291's & the cylinders have cleaned up nice & only needed a piston after being straight gassed. Hope that helps.

 

[gasax]

562 cylinder is essentially the same as a 555. the crank is different though. The 555 is wider by the distance of the two sheet metal cages that hold the stuffers it's really matching the crank with the stuffers with the 562 el48 and ignition. So think of it as a three part deal. Crank carb ignition. It's probably ok to mix a 555 non stuffer crank with the 562's el48. Just that's a lot of stuff. A stock 555 with a compression hike and a muffler mod is what I would do.

Yes , I bet the stuffers are reducing the crankcase volume to work with the revboost feature of the coil to give the snappier response .
I checked part numbers for the carbs on a site and it listed them having the same #'s .
What would be your option for bumping the compression ?

 

[gasax]

The cylinders on the 562 also have a much nicer looking transfer port cover , made to flow much better than the 555 and cant be bought seperate from what I am seeing

 

[weimedog]

Yes , the et the stuffers are reducing the crankcase volume to work with the revboost feature of the coil to give the snappier response .
I checked part numbers for the carbs on a site and it listed them having the same #'s .
What would be your option for bumping the compression ?

The transfer caps have more cross sectional area on the 562's for those rpms. And Yes they would help. I deck the cylinders and cut the flange so it won't interfere with the case. Have to relieve the cases under the transfer caps too. Get to .020 squish. Also raise that skirt right at the transfer about .100...on a 562 I go further and do a pop-up on mine. Chucking the piston on those takes a bit of thought.. then muffler gets cut up a bit

 

[weimedog]

On the carbs my bet is if u order a carb u Get a el48...the 562's carb. lowest common denominator

 

[gasax]

The transfer caps have more cross sectional area on the 562's for those rpms. And Yes they would help. I deck the cylinders and cut the flange so it won't interfere with the case. Have to relieve the cases under the transfer caps too. Get to .020 squish. Also raise that skirt right at the transfer about .100...on a 562 I go further and do a pop-up on mine. Chucking the piston on those takes a bit of thought.. then muffler gets cut up a bit

By flange , do you mean skirt ?
Do you re-establish your port heights after dropping the cylinder ?
What do you mean by chucking the piston ?

 

[weimedog]

I leave the exhaust and transfers and add a little intake duration. Couple of degrees. Seemed to help the 555. I use a lathe. A Chuck is what holds the part time be turned.

 

[gasax]

I leave the exhaust and transfers and add a little intake duration. Couple of degrees. Seemed to help the 555. I use a lathe. A Chuck is what holds the part time be turned.

I should have been more clear , what modifications are you making to the piston ?
I am by no means a machinist but I do have a couple of lathes , just picked up a little Myford acutally .

 

[RIDE-RED 350r]

Weimdog is one of the first to start digging into and understanding the 555/562 saws and how to mod them at varying levels. His advice is well worth following.

 

[weimedog]

I did a couple of videos then. Best to look there than me write a book. But one is specifically how I chuck an asymmetric piston. Lol but trying lead you thru the process so u understand my second post in this thread...

 

[gasax]

Weimdog is one of the first to start digging into and understanding the 555/562 saws and how to mod them at varying levels. His advice is well worth following.

Absolutely , it's people like him that make me love the internet , I only hope I'm not being too much of a pain...

 

[weimedog]

Did a video on the interference issues encountered when lowering the cylinder. But to me the 555 is a really cool saw stock..

 

[weimedog]

One fellow takes advantage of the really thick gasket....uses a thinner gasket made by him to drop the cylinder. ..still I worry about the interference issues..hence that video

 

[RIDE-RED 350r]

Absolutely , it's people like him that make me love the internet , I only hope I'm not being too much of a pain...

There's no such thing as a human that knows everything, and anyone who knows something had to start somewhere....No, you aren't being a pain.