MasterBlaster
Administrator Emeritus
Slovenia?
MS260 port job
- Thread starter sotc
- Start date
- Replies 210
- Views 32K
T
T0RN4D0
Guest
Yes mr. admin. A tiny country in Europe, sorry for barging in on your forum. Had a little problem with the registration yesterday, i think someone deleted my account. 
sotc, thanks for the quick reply. My fingers are itchy but i'm waiting for a tach to come in my mailbox. I want to check the stock RPM and how far tuning by ear is from the recommended values.
sotc, thanks for the quick reply. My fingers are itchy but i'm waiting for a tach to come in my mailbox. I want to check the stock RPM and how far tuning by ear is from the recommended values.
MasterBlaster
Administrator Emeritus
Welcome to the TreeHouse, mate. You're our first Slovenian! I guess they speak English there?
top_notch
Treehouser
Slovenia, cool! Welcome Torn4do.
rskybiz
TreeHouser
Welcome!
Al Smith
Mac Daddy
FWIW you can get into the upper transfers with a straight shaft die grinder .It takes an especially long shafted tool though .
If you have a variable speed die grinder,Dremal ,whatever ,cut the speed down because going sideways into a port it can get away from you before you know it .This is not a race,take your time .
If you have a variable speed die grinder,Dremal ,whatever ,cut the speed down because going sideways into a port it can get away from you before you know it .This is not a race,take your time .
Burnham
Woods walker
Don't forget to open the muffler outlet, too.
Welcome!
Welcome!
T
T0RN4D0
Guest
Thanks for all the welcomes. We have our own language, but you have to learn a few to get by easier 
Burnham, ofcourse, muffler mod will be the first thing. I have the type that has a 2 oultet holes on the side. Im thinking of opening it up in the front and putting a wired mesh guard over it. Must watch out that i dont go too big tho.
Al Smith, i have a decent Dremel with the flex shaft (has a smaller handle on the end) and i maybe could do it, but that seems awfully risky and a great way to ruin the cylinder. And i'm not quite sure what to do with the side ports. Just widen them?
I think i'm probably going to leave them alone, because I don't plan on racing the saw or using it in big wood. I do want to put a 3/8 18" bar on it, because i have a few spare loops and a bar that's currently on my 046. But i think anything close to 15" i'm grabbing the big gun, so the longer and wider b&c shouldn't be a problem.
Burnham, ofcourse, muffler mod will be the first thing. I have the type that has a 2 oultet holes on the side. Im thinking of opening it up in the front and putting a wired mesh guard over it. Must watch out that i dont go too big tho.
Al Smith, i have a decent Dremel with the flex shaft (has a smaller handle on the end) and i maybe could do it, but that seems awfully risky and a great way to ruin the cylinder. And i'm not quite sure what to do with the side ports. Just widen them?
I think i'm probably going to leave them alone, because I don't plan on racing the saw or using it in big wood. I do want to put a 3/8 18" bar on it, because i have a few spare loops and a bar that's currently on my 046. But i think anything close to 15" i'm grabbing the big gun, so the longer and wider b&c shouldn't be a problem.
Al Smith
Mac Daddy
Do a little reading on the subject before you get to carving away .
You have two basic reasons for reworking the upper portion of the transfers .First is get a better sweep of the intake side of the piston to purge the cylinder of the remaining residue of exhaust gasses .
Secondly and also important is when you increase the rpms you decrease the time the ports are opened so you must increase the port sizes .There's formulas on the subject but I can't remember them off the top of my head .
An example of that can be studied for example on two Stihl Models ,the largest and almost the smallest being the 084 and the 200T .In comparrison to cylinder size the stock ports on an 084 are relatively small yet on the 200T they are huge by comparrison . The 084 runs in the neighborhood of 11,500 more or less and the 200 can wind up to 15,000 depending on how it's tuned .
You have two basic reasons for reworking the upper portion of the transfers .First is get a better sweep of the intake side of the piston to purge the cylinder of the remaining residue of exhaust gasses .
Secondly and also important is when you increase the rpms you decrease the time the ports are opened so you must increase the port sizes .There's formulas on the subject but I can't remember them off the top of my head .
An example of that can be studied for example on two Stihl Models ,the largest and almost the smallest being the 084 and the 200T .In comparrison to cylinder size the stock ports on an 084 are relatively small yet on the 200T they are huge by comparrison . The 084 runs in the neighborhood of 11,500 more or less and the 200 can wind up to 15,000 depending on how it's tuned .
woodworkingboy
TreeHouser
With a Stihl 028, I simply took out the base gasket and used a sealant. It gave me a good squish. I always meant to get back and do a proper porting on it, but the higher compression made the saw lively enough as is. The torque seems to cover any loss in rpms, if there is some. I also tricked out the muffler, standard op.
Al Smith
Mac Daddy
I've had reasonabley good success with every saw I ever reworked .They never did exceptionally well running over the blocks at a GTG but they shine in the woods which is where it really counts .
SouthSoundTree
Treehouser
Somebody clue me in on 'squish', please.
T
T0RN4D0
Guest
It is the space between the top of the piston and the area around the outside on the top of the cylinder. The lower the squish, higher the compression. High squish is leaving power in the saw, but generally you don't want to go far below 0.02".
woodworkingboy
TreeHouser
The 036 on the 034 case is at .018 squish. It's the 'Leatherface' signature model.
Al Smith
Mac Daddy
I think the 200T is setting on about 20 thou .It has a domed piston though .The 038Mag is at 23 thou ,domed also .038 AV around 26 ,factory hemi domed piston .
Using soft solder you smash and micrometer it's hard to get a real accurate reading .Close enough I suppose .
Using soft solder you smash and micrometer it's hard to get a real accurate reading .Close enough I suppose .
T
T0RN4D0
Guest
I finally took on this project. First i had some problems with my weedwhacker and parts, so i didn't want to open another engine before i finished the first.
I just disasembled everything and im getting too low squish numbers without the gasket, in some places its going close to 0, so i think i'll just put the base basket back in. There was a lot of carbon on top of the piston and i rinsed it off, maybe i have to work harder on removing the carbon in cylinder ceiling.
I guess its dremmel time now, i'll worry about that later.
I just disasembled everything and im getting too low squish numbers without the gasket, in some places its going close to 0, so i think i'll just put the base basket back in. There was a lot of carbon on top of the piston and i rinsed it off, maybe i have to work harder on removing the carbon in cylinder ceiling.
I guess its dremmel time now, i'll worry about that later.
woodworkingboy
TreeHouser
Carbon usually has very minimal effects on squish. You often don't find 0 without the base gasket, how thick is it?
T
T0RN4D0
Guest
I rechecked and the carbon shouldn't have been an issue as you said. The squish is not exactly 0 but but 0.005 is close enough. Maybe i'll try making an alum gasket if i can find anything in the 0.01 range.
The base gasket is 0.02 tho, so its probably ok to just put that back in. When i tighten the nuts i think i'll be in the 0.025 to 0.030 which doesn't sound that bad. I'll measure squish with the gasket tomorrow.
Today i've done the exhaust port and i gutted the baffle in the exaust and matched the exhaust inlet to cyl outlet.. Tomorrow i'll attack the cyl intake and maybe i'll try my luck with side transfers, not sure yet.
The base gasket is 0.02 tho, so its probably ok to just put that back in. When i tighten the nuts i think i'll be in the 0.025 to 0.030 which doesn't sound that bad. I'll measure squish with the gasket tomorrow.
Today i've done the exhaust port and i gutted the baffle in the exaust and matched the exhaust inlet to cyl outlet.. Tomorrow i'll attack the cyl intake and maybe i'll try my luck with side transfers, not sure yet.
woodworkingboy
TreeHouser
You could also shave down the cylinder base a tad. Most easily done on a lathe, but it wouldn't be so difficult to remove that minimal amount by sanding, but also having to keep the base square to the bore.
Al Smith
Mac Daddy
FWIW you don't really need an aluminum base gasket .About any solid paper will work .For one thing that low on the cylinder it doesn't get that hot plus it really isn't holding much pressure .Fact if I remember correctly the base gasket on my souped up 200T is 10 thou thick .Reason being I screwed up cutting down the cylinder base with my measurements .Not paying attention in other words .
woodworkingboy
TreeHouser
That's a good point, Al, about the lack of hostile environment down there at the cylinder base. I was surprised how well the gasket goop holds up there, not needing replacement after a number of years. I guess that is the reason.
T
T0RN4D0
Guest
Well i made a paper gasket and covered it with threebond on both sides. The paper was bout 0.013 Don't know yet what clearance that gives me, i'll try measuring squish throgh spark plug hole tomorrow. I want to leave the sealant to cure before i crank it.
woodworkingboy
TreeHouser
You might have saved yourself some trouble by measuring with the gasket in place before adhering it with the sealant. The sealant will add no appreciable thickness or change of squish. If you get slightly under .020 you might still be ok, though it is less than what is normally recommended for a working saw. Consider it risky...risky with possibly excellent torque.
