FATGUY
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I don't mean to hijack this thread, I just look down and see so many knowledgeable members here....
A Tale of Three Saws
- Thread starter blsnelling
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Yes, that's why you must have a Schrader valve on the end of the hose. That's also why it takes more pulls on my Snap-On guage with the long hose it has.
To the first, it simply is the small size of the cylinder.
To the second, you can derive theoretical compression from the trapped volume compression ratio (but not from the conventional measurement, which is why it is useless), but actual compression will always be less than that depending on the quality of the seal.
FATGUY
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so if two trains leave at the same time, one is blue oval powered, the other is bowtie powered, we're gonna sit on our tailgates at the end of my street and drink beer? I love it. I wish I would have taken this kind of hands on approach while I was in school.....Oh wait, I did...
Gotta love the new math.
Um, the Husky is 5oz lighter when holding 4oz more oil, so I'd say the Husky is 9oz lighter.
Well, since it's May...(I'm not displaying the pics because I don't want to clutter the thread with huge calendar scans)
I like those older calenders better...the girls seem "classier"...
mtngun
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Depends on who you are talking to.
Uncorrected compression ratio (UCCR) is calculated just like a 4-stroke, volume at BDC divided by volume at TDC.
Corrected (or effective, or actual, or trapped, or true) compression ratio (CCR) only counts the swept volume above the exhaust port. According to A. Graham Bell, the Japanese prefer to use the corrected compression ratio.
Says Bell "I prefer ..... the old uncorrected figures which make sense to me, even if they don't make sense to the Japanese. If there were any basis to the Japanese system we should be able to race a PE175 in the 100cc class as its effective displacement is only 94cc, but try getting any motorcycling or karting organization to swallow that one ! What I would really like to know is why isn't the PE175 called a PE100 ?"
Bell then points out that a tuned pipe will force any fuel/air charge which has escaped into the exhaust port back up to the port and into the cylinder. "Therefore the 72cc of fuel/air mix that appears to be lost out of the PE175's exhaust is not really lost, it is just temporarily misplaced."
When Bell talks about high compression causing problems with heat, detonation, and pumping losses, he is talking about 13:1 - 15:1 compression ratios (UCCR) used on racing bikes.
The typical Stihl is only 8:1 UCCR, maybe 9:1 if you are lucky.
Dolmars and Solos would appear to have 10:1 - 11:1 UCCR, judging by the compression data AS members have posted.
Thanks for the info.
So it looks like most Dolmars would run better on 90+ octane pump fuel, and the Sthils and most other saws with under 10:1 compression will run best on 89 octane. At least that's how I see it with 4 stroke engines.
Now how much does oil drop octane? 32:1 - 40:1 - 50:1
FATGUY
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awesome, awesome info Mntgn!
MCW
Somebody's talking crap here & it ain't the tree!
Thanks for the info.
So it looks like most Dolmars would run better on 90+ octane pump fuel, and the Sthils and most other saws with under 10:1 compression will run best on 89 octane. At least that's how I see it with 4 stroke engines.
Now how much does oil drop octane? 32:1 - 40:1 - 50:1
I wouldn't trust him, he looks like a criminal in his avatar
Nah great info mate, very interesting.
Plans are to test the saws tonight. The challenge is going to be prepping the log. These are Oak logs in the 40" diameter ball park. I'm going to have to slab the sides in order to be able to reach through with my 32" bar. I'll also have to either jack and elevate the log, or slab the bottom off as well. I'll be using my 084 for the sides, but will opt for something much lighter on the horizontal bottom cut. I'm not looking forward to this part.
It will be quite hot and somewhat humid for this test. Temps will be about 85 with about 50% humidity.
All saws will be wearing 8-pin rims and pulling the same 32" Granberg-filed Stihl RSC chain.
Along with the 7901, 390, and 660, I plan to test my 066 "tractor saw". I'm real curious how it will compare. There might be another saw or two thrown in the mix as well. Here's to hoping we don't have thunderstorms this evening
It will be quite hot and somewhat humid for this test. Temps will be about 85 with about 50% humidity.
All saws will be wearing 8-pin rims and pulling the same 32" Granberg-filed Stihl RSC chain.
Along with the 7901, 390, and 660, I plan to test my 066 "tractor saw". I'm real curious how it will compare. There might be another saw or two thrown in the mix as well. Here's to hoping we don't have thunderstorms this evening
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Winn R
Rambling Wreck
I love this place.
FATGUY
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Plans are to test the saws tonight. The challenge is going to be prepping the log. These are Oak logs in the 40" diameter ball park. I'm going to have to slab the sides in order to be able to reach through with my 32" bar. I'll also have to either jack and elevate the log, or slab the bottom off as well. I'll be using my 084 for the sides, but will opt for something much lighter on the horizontal bottom cut. I'm not looking forward to this part.
It will be quite hot and somewhat humid for this test. Temps will be about 85 with about 50% humidity.
All saws will be wearing 8-pin rims and pulling the same 32" Granberg-filed Stihl RSC chain.
Along with the 7901, 390, and 660, I plan to test my 066 "tractor saw". I'm real curious how it will compare. There might be another saw or two thrown in the mix as well. Here's to hoping we don't have thunderstorms this evening
looks like we're good on our end, Andre's on his way down to the shop.
rms61moparman
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There you beotches go having loads of fun again without me!!!
Mike
Mike
MCW
Somebody's talking crap here & it ain't the tree!
Good stuff Brad. Not sure if you can get a vehicle or winch into where these logs are but I've found that they are easier to wrap a strap or rope around if possible (like a yo-yo) then tow them (to the side so they roll, not tow them lengthways) onto some other logs to get them off the ground. I've done that before at my place and it works well. Only problem is you can sometimes get dirt/mud in the bark. I've also strung rope/cable through adjacent trees then towed logs off the ground. May not be possible here though. Good luck and looking forward to the grand comparo
SawTroll
Information Collector
I have been out for close to a week, so I don't know what has been posted later - but you got the maths wrong!
From the posted numbers, the difference is 9.0 oz, not 1 oz!
MCW
Somebody's talking crap here & it ain't the tree!
I have been out for close to a week, so I don't know what has been posted later - but you got the maths wrong!
From the posted numbers, the difference is 9.0 oz, not 1 oz!
Aren't you a metric man Sawtroll?
I think you meant to say the 390XP is 252 grams lighter than the 660, or just over a pound
The saws have been run, but the results are not in. I haven't had a chance to do anything with the vids yet. That's going to take a good while.
Here's the cant I made. It measures 29" wide x 17" tall x 48" long. I wanted to use the entire length of the 32" bar, minus clearance for the dawgs. This is the first time I ever tried anything like this. Getting the bottom slab out was a real pain!
Here's the cant I made. It measures 29" wide x 17" tall x 48" long. I wanted to use the entire length of the 32" bar, minus clearance for the dawgs. This is the first time I ever tried anything like this. Getting the bottom slab out was a real pain!
