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.
Is there any reason for the mismatch with the case halves at the base?
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.
Looks familiar....
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I'm not touching that Will, lol!![]()
Whoops. Maybe I don't really know what to look atI thought they looked OK.
I see what you mean now compared to the Mahle setup![]()
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:They've always pretty much been that way. Very few saws I get have perfectly matched case openings.
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.![]()
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.
now that you have compression of 180+ psi what kind of fuel are you running?:monkey:
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,
opcorn:
opcorn:
opcorn:
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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
Brad, thank you once again for sharing your excellent data.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.
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.
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.