A Tale of Three Saws

[Jacob J.]

Is there any reason for the mismatch with the case halves at the base?

They've always pretty much been that way. Very few saws I get have perfectly matched case openings.

 

[Jacob J.]

Looks familiar....

 

[Andyshine77]

It's very interesting to me that the last of the older design, legendary Stihls being made and sold right now seem to all have these sub-par parts. I guess it is promising that the new strato stuff has the high end components, but it is frustrating to think that a company like Stihl would tarnish their reputation like this. I hadn't heard about some Stihl cylinders being chromed instead of NiSi coated until Brad's post, but that is unbelievable.

It's been happening for a little while now,and like you said with saws that are on their way out. It's just the way things are with all manufacturing right now, profit over everything.

 

[AUSSIE1]

Looks familiar....

Aaargh...............you could gain a little area in the corners Jacob!

 

[parrisw]

I'm not touching that Will, lol!

LOL, you know you wana touch it just a little!

 

[splitpost]

Whoops. Maybe I don't really know what to look at I thought they looked OK.

I see what you mean now compared to the Mahle setup

yeah i ment compared to mahle,but really some of the aftermarket kits are better castings visually

 

[arborjockey]

They've always pretty much been that way. Very few saws I get have perfectly matched case openings.

how does that work out with the primary compression? do the transfers line up? Im well versed in small engines not chainsaw. now that you have compression of 180+ psi what kind of fuel are you running?:monkey:

 

[OhioGregg]

Dan my 362 has a Mahle topend and it's very nice looking from what I can see. The Gilardoni cylinders I've seen are also top of the line, in fact maybe the best of the bunch IMHO.

I would tend to agree with Andre on the Gilardoni cylinder quality. I was impressed with it. Here is a few pics of one for a Poulan Pro Super 380.
LOL, I got a Poulan pic in thread about the Big Two.

Gregg,

 

[MCW]

It's very interesting to me that the last of the older design, legendary Stihls being made and sold right now seem to all have these sub-par parts. I guess it is promising that the new strato stuff has the high end components, but it is frustrating to think that a company like Stihl would tarnish their reputation like this. I hadn't heard about some Stihl cylinders being chromed instead of NiSi coated until Brad's post, but that is unbelievable.

I don't think Stihl would expect people like us to pull their new saws apart and find out that their quality is dropping
I'm not sure if their reliabiity can be questioned but at the same time we're still paying the same, or more, for an MS660 with poorer quality internals as we were with Mahle internals...

 

[MCW]

now that you have compression of 180+ psi what kind of fuel are you running?:monkey:

I run all 98 octane (RON) in my saws at 50:1 (apart from my 3120 at 30:1) and have never had an issue with compressions up to 210psi. My Dolmar 5100-S has about 210psi and my two 7900's are 180psi and a tad under 210psi. My 5100-S is stock and untouched and despite running this saw and not even touching the tune for over a year I only found out it's compression a few weeks ago - it's a pig to start cold with no decomp .

 

[FATGUY]

I would tend to agree with Andre on the Gilardoni cylinder quality. I was impressed with it. Here is a few pics of one for a Poulan Pro Super 380.
LOL, I got a Poulan pic in thread about the Big Two.


Gregg,

The Poulan cylinder I did for Mike was one of, if not the truest cylinders I've ever machined the base on. Near perfect (~0.0005" axial runout)

 

[Stihlofadeal64]

opcorn:opcorn:opcorn:opcorn:

+1 for me here!:biggrinbounce2::biggrinbounce2::camera:

 

[husq2100]

Gilardoni used to make cylinders for a lot of the big saws- Pioneer P-62, Husky 2100, Partner P100, Olympyk 999. The cylinders they made back then were works of art- near to perfectly symmetrical ports, perfect plating that was rock hard, nicely finished combustion chambers with no casting lines, etc. I almost hated porting those older saws since the cylinders looked so good stock.

what husky 2100 cylinders did they do? how do i tell?

Serg

 

[Jacob J.]

what husky 2100 cylinders did they do? how do i tell?

Serg

Serg-

They will say Gilardoni on the base. I don't know if there was a specific run or serial number range. I've had two in my hands, I've given both away.

 

[mtngun]

The MS660 has been measured and is apart. Here are some specs on it.

Compression - 158 psi
Squish - .019"

Exhaust - 95° ATDC - 170° Duration
Transfers - 120° ATDC - 120° Duration
Intake - 80° BTDC - 160° Duration
Blowdown - 25°

Brad, thank you once again for sharing your excellent data. We all learn from threads like this one.

So...... the Stihl has a respectable 158 psi, but ....... that's all you're going to get, without a pop-up. The tight squish gives you no other option.

How did the top of the bore look ? Is there a gouge, or missing plating, at the very top of the bore ? I presume the swept portion of the bore must be good or else it wouldn't be blowing 158 psi ?

I began reading Bell's 2-stroke book last night, and since this thread has a lively discussion on the merits of pop-ups and high compression, I took note of what Bell had to say on compression:

"Something you must always remember when dealing with two-stroke engines is that increasing the compression ratio will not give a power gain equivalent to that which you would pick up with a four-stroke engine. Heat is the enemy of two-stroke engines and pushing the compression ratio to give an expected 6 % power increase will possibly result in a 1% - 2% rise at the most; the rest will be lost in heat energy and pumping losses. However, at lower engine speeds the cylinder will not be completely filled with fuel/air mixture and the power may jump by 3% - 4% because there is not such a heat loss. This is, in fact, the real benefit of raising the compression ratio, not to increase maximum power but to pick up mid-range power and possibly widen the power band ."

In other words, raising compression may not result in faster timed cuts on cookies, which is mostly a function of peak power, but compressons helps with the mid range, making for a more user-friendly work saw.

 

[FATGUY]

Brad, thank you once again for sharing your excellent data. We all learn from threads like this one.

So...... the Stihl has a respectable 158 psi, but ....... that's all you're going to get, without a pop-up. The tight squish gives you no other option.

How did the top of the bore look ? Is there a gouge, or missing plating, at the very top of the bore ? I presume the swept portion of the bore must be good or else it wouldn't be blowing 158 psi ?

I began reading Bell's 2-stroke book last night, and since this thread has a lively discussion on the merits of pop-ups and high compression, I took note of what Bell had to say on compression:

"Something you must always remember when dealing with two-stroke engines is that increasing the compression ratio will not give a power gain equivalent to that which you would pick up with a four-stroke engine. Heat is the enemy of two-stroke engines and pushing the compression ratio to give an expected 6 % power increase will possibly result in a 1% - 2% rise at the most; the rest will be lost in heat energy and pumping losses. However, at lower engine speeds the cylinder will not be completely filled with fuel/air mixture and the power may jump by 3% - 4% because there is not such a heat loss. This is, in fact, the real benefit of raising the compression ratio, not to increase maximum power but to pick up mid-range power and possibly widen the power band ."

In other words, raising compression may not result in faster timed cuts on cookies, which is mostly a function of peak power, but compressons helps with the mid range, making for a more user-friendly work saw.

I think that widening the powerband is more beneficial than some may think, particularly in a 60-80cc saw where the size of wood cut with the saw is not constant. Excellent post! Great info, thanks for sharing.

 

[Andyshine77]

I think that widening the powerband is more beneficial than some may think, particularly in a 60-80cc saw where the size of wood cut with the saw is not constant. Excellent post! Great info, thanks for sharing.

This is so, however if you're pushing the saw heat may cause the engine to loose some power as well.

 

[Andyshine77]

Brad, thank you once again for sharing your excellent data. We all learn from threads like this one.

So...... the Stihl has a respectable 158 psi, but ....... that's all you're going to get, without a pop-up. The tight squish gives you no other option.

How did the top of the bore look ? Is there a gouge, or missing plating, at the very top of the bore ? I presume the swept portion of the bore must be good or else it wouldn't be blowing 158 psi ?

I began reading Bell's 2-stroke book last night, and since this thread has a lively discussion on the merits of pop-ups and high compression, I took note of what Bell had to say on compression:

"Something you must always remember when dealing with two-stroke engines is that increasing the compression ratio will not give a power gain equivalent to that which you would pick up with a four-stroke engine. Heat is the enemy of two-stroke engines and pushing the compression ratio to give an expected 6 % power increase will possibly result in a 1% - 2% rise at the most; the rest will be lost in heat energy and pumping losses. However, at lower engine speeds the cylinder will not be completely filled with fuel/air mixture and the power may jump by 3% - 4% because there is not such a heat loss. This is, in fact, the real benefit of raising the compression ratio, not to increase maximum power but to pick up mid-range power and possibly widen the power band ."

In other words, raising compression may not result in faster timed cuts on cookies, which is mostly a function of peak power, but compressons helps with the mid range, making for a more user-friendly work saw.

Good info, it for the most part confirms what I know, and what been told by a few saw builders.

It looks like this 660 would benefit from a little machine work.

 

[AUSSIE1]

Increasing the midrange should increase the speed at which it cuts cookies due to being able to lean on the saw more and/or have more aggressive chain specs.
Some saws don't sound like they are working any quicker than a stocker, but are cutting quicker.

 

[wigglesworth]

Real high (200 psi) cold cranking compression means nothing more than you have a good ring seal, or a smallish combustion chamber.