ILikesEmGreen
Another crazy Poulan Fan
...Usually comes with a dose of embarrassment and side-steppin' on their words too.
Nik's Poulan Thread
- Thread starter FATGUY
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ImNotASwede
ImNotaSwede
That makes sense. I was wondering how much of that was related to thermal expansion. I'm no stranger to engine tuning....but I usually stick with stuff with tires on it....although most of the principles are the same. Regardless, thanks for all the solid info
ImNotaSwede I forgot to mention all of my poulan saws that I have worked on are flat top pistons. Some other brands do have some dome top pistons but checking for clearance between the piston top to the top of the cylinder is still the same.
Some pro saw builders have taken flat top pistons and welded a dome to the top of them to bump up the compression. Some believe and some dis-agree that it changes the flow of gases through the combustion chamber. I do not know enough about it to have a definite opinion.
Some pro saw builders have taken flat top pistons and welded a dome to the top of them to bump up the compression. Some believe and some dis-agree that it changes the flow of gases through the combustion chamber. I do not know enough about it to have a definite opinion.
ImNotASwede
ImNotaSwede
I was wondering about that. I was/am tempted to try a stihl piston (s) in my pro 330. The MS280 and a couple others iirc have a piston of the same diameter and wrist pin diameter and height, but with different skirt and piston top shapes....plus they're cheap and plentiful....wonder about the piston skirts too...the 380 has much less skirt material than the 330...
We'll remember the skirt helps in controlling when the ports will open and close. Think of the timing of when the ports open and close as the cam in a 4 stroke engine.
Tractorsaw1
ArboristSite Guru
I got a 60cc cylinder from my 380 that has a stihl 039 piston ready for transplant. 3000 did you take any pictures when you worked over your 3750?
No I am afraid I did not.
The only pictures I took were the before and after welding job I did on the crankcase where someone had ground away a part of it.
Tractorsaw1
ArboristSite Guru
Just curious if you blended the bottom of the transfer ports to the cylinder, pretty good step there. I'll probably blend that out, widen the intake & exhaust some & make a pop up piston on the stihl piston & see how it acts.
No
When you do yours take some pics and let us know how it went.
I did not mess with the transfers on my 3750. I really liked the design of the transfers in those particular saws so I left them alone. I did make a video of it cutting a cookie.
When you do yours take some pics and let us know how it went.
Tractorsaw1
ArboristSite Guru
I will, this saw was to be the super 380 magnum, Kinda wondering which cylinder may cut faster with an 18" bar & 3/8" chains
ILikesEmGreen
Another crazy Poulan Fan
Friday morning and 57° with a high of 79°... Sounds like a good day to hit the highway for a little CAD roadtrip. Gonna go check out that little shop in the middle of no where that had the 455 tucked back down in "the basement". It might be like opening an Egyptian tomb down there. Ain't no telling what I may stumble across. He's been there for years. I'll have some pics after bit... Just not of the sign. Hehe
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well???
ILikesEmGreen
Another crazy Poulan Fan
Just a little teaser... it for dark before I could get any pics. Got a little more poking and wiping to do yet, but it's cleaning up quite nicely. Gotta replace the broken bar tensioner stud (luckily i can just order two now as I need one for my 655), and replace the missing chain brake band. P&C shiny and clean. Dumped the bad gas out, washed the tank with fresh, and replaced with fresh mix. Popped on choke third pull and cranked on the next off choke pull. Warmed up great and throttled out very strong. Gotta get a 24" for it now. Walked outta there grinnin like a mule eatin briars for a $50 bill.. And leads/dibs on others. :biggrin:
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ILikesEmGreen
Another crazy Poulan Fan
Good timing on your question... Haha
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ILikesEmGreen
Another crazy Poulan Fan
That pp455 had P45CB on the id tag. I know it's a Pioneer saw, but what does the "CB" designate... if anything specific? Chain brake model possibly?
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ILikesEmGreen
Another crazy Poulan Fan
10-4... That's what i figured. 'Preciate it! 
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ILikesEmGreen
Another crazy Poulan Fan
bah....sorry about that Acornhill...i typed that give beer "shortcut" into my phone through tapatalk thinking it would some how give you a beer. I didn't think about it asking for one. lol. Carry on... :
procarbine2k1
Addicted to ArboristSite
Not quite sure Poge, probably the same saw, but I know there were variations. This one is a 54cc open port, nikasil cylinder w/ single ring piston. This saw was the one I got lucky on as an Ebay parts saw/ non runner. Someone had spent a great deal of effort trying to start it, by how much fuel/ who knows what was in the crankcase. Impulse hose was rotted off. I replaced that, along with a good lookover on the carb and we were back in business. I cut the base and ported it before I put it back together. I cant remember, but think I have about .030 off the base on this one. Squish was .022 or something of the like. Makes good compression, not a race saw by any stretch but a real good runner. It is getting stronger as I put more time on it.
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