Porting an 090
- Thread starter pioneerguy600
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hoss
Addicted to ArboristSite
Please be sure to show us pics of the jug AFTER the surgery.
opcorn:
opcorn:
Please be sure to show us pics of the jug AFTER the surgery.
Oh for sure I will, the time to go under the grinder is drawing nearer, just laying the ground work right now but once its all sorted out the porting takes only a couple of hours.
Pioneerguy600
How much are you leaving for the ring ends to ride on?
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How much do they need??
Is there a formula tha you can give me?
Any saw building formulas would be appreciated!..
thanks Brad..
How much do they need??
Is there a formula that you can give me?
Any saw building formulas would be appreciated!..
thanks Brad..
I don`t think there is a formula for leaving enough cylinder wall for the piston ring end gap to be supported on, you must carefully measure the retaining pin locations and transfer that location onto the cylinder wall befor starting to cut the ports. As the rings wear the gap will widen a bit but not excessively, 8-10 thou and they will be worn out as they start out new at around 9-10 thou. gap, add that much again for wear and your at 20 thou. I will leave around 100 thou or 1 mm out past the pins for the rings to ride on, this is so that the ring ends do not travel over the opening of the port, they might pop out enough to snag, if they did not snag it would cause a lot of wear in the ring groove of the piston.
Pioneerguy600
roalco
ArboristSite Member
Hey Pioneerguy, I think I just got the twin of the saw "Lawrence the Enabler" sent you from BC!! I just picked this one up in the BC interior (thank you CL!) It's got the original 5 foot stihl duromatic bar, original (never sharpened) stihl full deck chain, and a 24" bar (a Draper Penfield "Wear Tough"). The guy was the original owner and cut 12 slabs with it and put it away..., maybe 3 hours running time, and the Stihl and 090 labels on the saw top still have their protective tape on them!
Great thread on porting, but I think this one's gonna stay stock.
Great thread on porting, but I think this one's gonna stay stock.
Hey Pioneerguy, I think I just got the twin of the saw "Lawrence the Enabler" sent you from BC!! I just picked this one up in the BC interior (thank you CL!) It's got the original 5 foot stihl duromatic bar, original (never sharpened) stihl full deck chain, and a 24" bar (a Draper Penfield "Wear Tough"). The guy was the original owner and cut 12 slabs with it and put it away..., maybe 3 hours running time, and the Stihl and 090 labels on the saw top still have their protective tape on them!
Great thread on porting, but I think this one's gonna stay stock.
You get the one on Craigs List from over near Kelowna, that is a nice saw?
Pioneerguy600
Mastermind
Work Saw Specialist
What about it Jerry, has the deed been done yet? I've been waiting to see this one. I'm glad to see your port maps, I've made and used a few now...Macdizzy was where I found that info...I wondered if what I was doing looked it right or not. I feel the need to know what I'm doing before I start cutting...now that I've seen you doing that I don't feel like I'm wasting my time with it.
Not yet, I have been quite busy with other work and the days have been too nice to spend time inside. It`s turn is coming , and I find it very benificial to know where I started and also how far I have gone. I seem to always be doing the same saws cc wise and make time after time so the map tells me where I am going.
Pioneerguy600
roalco
ArboristSite Member
Yes, the one from Oyama. It was well worth the 5 hour drive (each way)! A good price and it looks like he'd only cut a bit of softwood with it, then put it away. It ran up on the third pull (some decent compression!!!) and sounds really good, now to break it down, clean it up and give it a good going over. I've got some fir to mill for a friend and might use it instead of my dolmar. It sure is a heavy one with that big bar tho'!!
Mastermind
Work Saw Specialist
What a saw. I can't imagine running something that heavy...but for milling...That is a great looking saw.
Brmorgan
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I saw that one! What are your plans on the 5' bar? I might be interested for the right price since I wouldn't mind having one for milling.
That was a good price for that saw, my alarm went off 9 mins after that saw was posted. It was a little far for me to drive out there to pick it up. LOL
Pioneerguy600
WesternSaw
Addicted to ArboristSite
Lawrence the "Enabler" aka "SawBroker"!
Roalco,I tried hitting on that 090 in a way also.He sent one reply back to me SOLD!
Good for you that looks to be in very nice shape!
Lawrence
Roalco,I tried hitting on that 090 in a way also.He sent one reply back to me SOLD!
Good for you that looks to be in very nice shape!
Lawrence
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roalco
ArboristSite Member
Thanks guys, I had been looking for one for a while now, lucked out and now it's found a good home! I'm really looking forward to doing some milling with it (well, as much as you can look forward to milling with a chainsaw LOL). Could have used this a few years ago when we took out some big fir on our place up the coast (7-8 foot on the butts)... Ahhhh, CAD and timber...
Those full AV models are a lot easier on the body than the old solid mount saws, actually they are quite smooth for bucking. Not all important for milling but still a very nice option.
Pioneerguy600
Wild Knight
ArboristSite Guru
FWIW, I have no experience with the 090; scrutinize my comments and make your own decision. But as a few general comments:
I like that you are using port maps. It is good to have a plan when doing a project, and IMO the best way to go about making a jug perform better.
The engineers aren't dummies. They can design these motors to do exactly what they want, though there are always compromises. What they do not have is much (any) oversight in quality control over modular components. Parts may even be built by different plants, maybe sometimes even different companies. The result is a motor, that once random parts are assembled, passes spec, but it not exactly what is on the drawing table. Alignments may be of a few thousandths here, casting flaws there, cutter marks, port mismatching, etc. etc. Point being, a basic blueprinting of the motor, simply getting the motor to its original spec, will make an significant difference in performance. Throw is an exhaust mod to correct for emissions standards, and you have a whole new baby.
That said, my conjecture is that your transfers are a bit aggressive. You've got a lot of experience, so you know it only takes small changes to make big differences. I think you are risking a loss of flow velocity (or at minimum, designed scavenging) by making such a drastic change. Ostensibly, it would be fine if you were trying to make a race saw, but you said you wanted it to stay in the 8500 RPM range. You can fill the combustion chamber with air using low volume and high velocity transfers or high volume and low velocity transfers. This saw is already turning low RPM, so increasing the volume of the paths the air is traveling, so drastically, at such low RPM, is potentially going to slow the velocity. Like said, if this were a 12-14K race saw, then the rules change. Metal is easy to take off, but a PITA to put back on
When it is all said and done, whether you are running 8500-9500 RPM, I think you'll notice the best performance gain in cutting by getting a much larger rim. That is, unless you do a lot of cutting of 5-6' trees, in which case I am very jealous
