Big_Wood
westcoast dweller
this is a thread with some pics for you guys.
http://www.arboristsite.com/community/threads/tearing-into-my-simonized-372xp.275721/
http://www.arboristsite.com/community/threads/tearing-into-my-simonized-372xp.275721/
How much better is a 372xp with the cylinder skirt removed?
- Thread starter Adam08ski
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That'd definitely a Simonized 372
I can hear it
Lol ...IDK...I saw the link show up and watched the vid. off the site and now its gone? Weird
stikine
ArboristSite Member
Fiber puller! 
I just thought you couldn't see the link. I guess my internet just dropped strength right after the vid. I saw the vidio a hand full of times about four yrs ago and thought that was a Simonized 372. After listening to it just after i posted it; It sounded a lot different on this device so i will retract that statement. i would need to hear it in real time.
To clarify: His domed 372 sounded much different and louder that a Walkerized 372. There wasn't anyone else in the game here. Both use the 266 muffler ears but Simon sightly bent open all three ports a little more as well opened up more.
I agree. The first couple I did, I raised that area quite a bit and used a windowed piston- it made the power band "peaky" and the sweet spot was very narrow. Later, thinking about when Pioneer used a similar arrangement, I had the squish band machined and kept the skirt area and dropped the jug further into the case and got more usable power.
Isn't that an open skirt single ring in that thread link Shane, Just like the one he had in my saw.
The only time I ever heard about the 268 piston being used was from the guy that owned the saw he built for that build off. I got mine built in 2007 so he may have gone to that at one point or just used it for the build as that open skirt single ring may have been snappier for Falling. (More 'Balanced')
The only time I ever heard about the 268 piston being used was from the guy that owned the saw he built for that build off. I got mine built in 2007 so he may have gone to that at one point or just used it for the build as that open skirt single ring may have been snappier for Falling. (More 'Balanced')
jmssaws
Addicted to ArboristSite
Did you run a lower exhaust than normal when you opened it up?
jmssaws
Addicted to ArboristSite
Transfer and case volume can be as big as you want and still have a wide power band,more so than a saw that hasn't been opened up if you do other things differently.
You have to decrease duration or you make a peaky saw.
You have to decrease duration or you make a peaky saw.
keep timing? Its a mismatch set up. Simon would slam it. No decking. 30mm .030 dome. He would go as wide as possible on the intake just so it covers. It tappers in to about a 1/4 passage at the sides. He doesn't touch the factory ridge especially. Only the sides as he is just channeling the fuel closer to the piston sides
It gets all the fuel it needs with the shorter skirt.
He had a thread on here I ran across and said he got 8.2 PH on the dyno.
Don't know when it was posted, post 2007 I'd presume. He told me then we was getting a 37% gain then.
Serious gains. That is some big power increase. I ideally would like to gain about of low end power out of this 372. It's a high revving performer. Unlike this 038 you cannot lean the hell on it in the cut. So if the intake was widened what was done to the exhaust port? Opened up as wide as the piston skirt allowed, side to side only?
Big_Wood
westcoast dweller
i would not port the jug if you don't know what you are doing. the 268 piston will get you what you desire. not knowing what your doing and doing it anyways could turn the saw into a turd.
it's the open skirt windowed 268xp piston simon uses and has always used. he could have used others as experiments but i've never seen it. i've pulled 3 apart that had the windowed open skirt piston in it. i've also pulled a few simonized 372's just done with the stock piston and they were a joke compared the the 268 piston saws he built, they were actually kinda ported though. i used the non windowed 268 piston and it worked great. any piston from those saws will work fine though. i built one with a golf 266 piston but removed it cause the amount the rod could walk was haunting me lol.
it's the open skirt windowed 268xp piston simon uses and has always used. he could have used others as experiments but i've never seen it. i've pulled 3 apart that had the windowed open skirt piston in it. i've also pulled a few simonized 372's just done with the stock piston and they were a joke compared the the 268 piston saws he built, they were actually kinda ported though. i used the non windowed 268 piston and it worked great. any piston from those saws will work fine though. i built one with a golf 266 piston but removed it cause the amount the rod could walk was haunting me lol.
Don't worry I am not interested in tampering with the cylinder anymore. But how do you get to know about 2 stroke porting without actual hands on learning? Surely you started somewhere?
I took this approach on my 038 Mag. Reading what port builders have done and executed said work on my Mag.
I ended up doing the 65% of the cylinder diameter measured across the surface of the bore on the exhaust port. Doing this on the 038 (farmertec) one I had resulted in widening the port to within 1.5mm of the piston skirt edge. I kept the same outer shape and general curve to the top and bottom of the port. It works really well with the modded muffler and base delete. It is definitely stronger. This is as brave as I want to be at the moment.
Chainsaw Jim
CJ Saws, LLC
I guess it's all about how you skin that particular cat.
I'll recommend it because I've ended up with really good gains by doing it. I've raised them all the way up to just below the ring lands and windowed the piston.
With that being said, there's no reason to risk it unless you have a spare piston and cylinder you don't mind throwing away in the event you mess it up.
Most will immediately bring up case volume. That's when I think of the crankcase stuffer cups in the 357 versus no cups in the 359. That's one hell of a case volume comparison.
I'll recommend it because I've ended up with really good gains by doing it. I've raised them all the way up to just below the ring lands and windowed the piston.
With that being said, there's no reason to risk it unless you have a spare piston and cylinder you don't mind throwing away in the event you mess it up.
Most will immediately bring up case volume. That's when I think of the crankcase stuffer cups in the 357 versus no cups in the 359. That's one hell of a case volume comparison.
Big_Wood
westcoast dweller
Was this a port job with the cut skirt included your talking about Jim or did you port the saw and then add the skirt cut after? just don't want to confuse a saw that would be strong anyways with a gain from that cut out cause it's more work! I ported a couple 372's and added the skirt cut after the port job. Also hogged out the ports after that. Didn't work for me and in fact seemed to lose some throttle response and low speed torque. I didn't bring it up as high as you though.
Chainsaw Jim
CJ Saws, LLC
If I remember right I did all that with only raising the exhaust two degrees. The uppers and intake are still stock. I've been wanting to go back inside that saw to degree it so I can finish what I started.
