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Author Topic: 372XP X-Torq Modding  (Read 45021 times)

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Offline NCFarmboy

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Re: 372XP X-Torq Modding
« Reply #460 on: January 07, 2018, 09:17:13 PM »
I use 80 grit - 120 grit for intake.  Whichever I have on hand.
Lots & Lots of Saws

Offline EvilRoySlade

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Re: 372XP X-Torq Modding
« Reply #461 on: February 10, 2018, 08:22:13 AM »
I can’t really tell but it looks like you didn’t open your intake window yet. You want to grind the upper part of the intake all the way up to the bottom of your piston skirt when at TDC. Always be sure to check where your ring is at BDC though before grinding. You’ll be fine in this case but no sense ruining a cylinder just cause someone said it’s okay.

Don’t go any wider though, it’s been mentioned earlier but it should be brought up again.

Offline Rx7man

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Re: 372XP X-Torq Modding
« Reply #462 on: August 12, 2018, 02:03:53 PM »
Wow, that was a marathon read to get through 24 pages, but I enjoyed it a lot.. I got a 372xt and the P&C aren't in that great shape so since I can't leave well enough alone, I'll fiddle with it!.. This is the only place I've seen a discussion that says you can get significant power gains from an XT saw, which makes me happy.

I am no pro at porting, but I've done a dozen or so saws of my own, I own half a dozen L65's, and they're a great learning platform since they're a pretty poor performer from the factory.  On my wildest one, I was going for top end power, so I went aggressive on the intake and exhaust durations, about 170* of exhaust and because of more machining of the base after porting the intake I ended up with about 180* of intake.. It sounded great on the bench free revving but it was an absolute dog in the wood, it was untunable because of intake reversion (when the intake charge reverses, the carb doesn't care which direction the air is flowing, so it adds fuel once the first time through, once on the reversion, and then once more as it draws it back in).. so at low RPM it was pig rich to be right at high RPM.

I came to the conclusion that my best gains would come from transfer port work since these saws had tiny transfers.. I had already done a little bit of work to them, but a lot more could be done.  They were a bottom fed closed transfer design and I converted them to a piston and bottom fed design, much like a 394 or Jred 930.. I windowed the piston and cut massive amounts from the cylinder wall.. I was limited in what I could do to the upper transfers because I don't have a right angle grinder small enough so I notched the piston to get more open time.  I was actually looking for more case volume because I wanted to lower the harmonic frequency in the case to reduce the reversion.. Basically a slower moving charge over a longer period of time because of the greater case volume.  
By the time I was finished, it felt like a whole new saw, stall RPM went up considerably from stock, so more low end torque, and in-the-cut RPM went up a lot, with more power everywhere.. It was very rewarding!

Now on the the XT... I haven't really studied it that much yet, but there are some things I'm surprised haven't been brought up yet.. In strato form, the bearings should be getting much better lubrication since the mix is quite rich to the bottom end, more important the less oil mix you run (like many of you, I like 32:1 for a hard working saw)
I haven't had the piston/cylinder in my hand very much to examine how the strato ports work, but since they go through the piston, that's a little bit of cooling to be had, but I haven't seen any one doing any smoothing/polishing on the piston cutouts, and it may be possible to change some of the timing there as well, though it looks hard to measure.  

Anyhow, I loved this thread (including the squarebody talk, I have '92, 93, and 94 dodge diesels, and have less fond memories of the '80 Blazer (I lived in it when I was too broke to afford rent))

Look forward to tearing my saw apart again when new rings get here and doing some work to it.. I think I'll try leaving it as a strato from the choke onward, and removing the divider in intake elbow, at least for now.. I want to see what I can get out of it without making it too thirsty.  Thanks for all the info and the great read!
Husky 2100x4, 394x2, 372xt, 288xp x2, 272xp, L65x6, "277" pipe saw
Stihl 064BB, 044, 028, 009L
Bunch of antiques and others

Offline ehp

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Re: 372XP X-Torq Modding
« Reply #463 on: August 15, 2018, 01:01:20 PM »
I still say one of the best motors out there, I got XT's that I ported out in the field that are still going being used by loggers and are 5 or 6 years old . Myself I leave the stock limited coil in saw but advance the flywheel, this stops the saw from over revving and hurting the crank/rod bearings when limbing and stuff . I gut everything but lots of guys donot . One of my own saws that I cut with and setup up will start and run the easiest of any saws you can run . Yep per hour I burn more gas but I cut a lot more wood per hour as well . Will I be rushing out to buy the new 572 , not to likely but that again is my idea

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