372XP X-Torq Modding

XP_Slinger · December 28, 2017, 10:25:37 AM

Quote from: SierraMtns on December 28, 2017, 12:11:22 AM
Great thread. I am currently porting my 365 x-torq. This is the first time I have ported a saw. I am a little nervous so I am and going slow.

I am hoping to post pictures soon.

Looking forward to it. I like how this thread keeps on rolling as more folks chime in with what they're doing.

SierraMtns · December 28, 2017, 08:47:43 PM

Quote from: XP_Slinger on December 28, 2017, 10:25:37 AM
Quote from: SierraMtns on December 28, 2017, 12:11:22 AM
Great thread. I am currently porting my 365 x-torq. This is the first time I have ported a saw. I am a little nervous so I am and going slow.

I am hoping to post pictures soon.
Looking forward to it. I like how this thread keeps on rolling as more folks chime in with what they're doing.

Yeah I was thinking about starting my own thread for this build but I think its cooler to join your thread and keep it going with the x-torq mods.

I primarily cut soft wood (Pine, Doug Fir, and Cedar) out here. On average the trees are 30" on the stump.

The stock squish is 0.43" and compression is 155 psi. This saw has 1.5 hours on it. I was getting 9,500-9,800 rpm cutting a Digger Pine log. The log was 29" and I am running a 32" bar with skip tooth and 50 ga chain. I had to feather the saw in the cut because the chain would stop if I was really pulling on it. My rakers might be a little low.

I swung by our local machine shop today to see about cutting the base and sadly they don't have a jig to do that. So it looks like I will either need to send it off or just do a base gasket delete.

Will be posting pictures soon.

SierraMtns · December 30, 2017, 11:40:38 PM

Ok guys here is where I am at. I marked out the areas I will be grinding. I will start on the lower transfers to get some practice. I put the base gasket on and will port match the gasket to the transfers.

What do you guys think? See anything you would be concerned with? I don't want to grind off to much.

SierraMtns · January 01, 2018, 09:13:30 PM

I did some porting today to the intake and lower transfers. I still need to get some stones to polish the ports.

What tools do you guys use to polish the ports? How smooth do they need to be?

Thanks

SierraMtns · January 01, 2018, 09:16:56 PM

I am not sure if you guys can see the upper ports but I tried to make them come together and not have the air hit a wall.

XP_Slinger · January 03, 2018, 01:02:11 PM

Hard to tell in the pics but I think you need to take more material out of the lowers. You've funneled them slightly but didn't really widen the port overall.

SierraMtns · January 04, 2018, 12:36:41 AM

Yeah I was thinking I needed to widen the lower transfers more too. I was censored with the screws holding the transfer caps. I marked out the area where I will widen them.

Also I marked out the exhaust port to widen and transfers.

What I am stuck on now is the transfers. I can not figure out a way to mark them out 0.30 lower. Do you guys have any tricks?

XP_Slinger · January 04, 2018, 08:05:31 AM

You're right to be concerned about the cap screws but you've still got plenty of room. Slow and steady and you'll be fine. The following video is how I find my height based on desired degree of opening. Courtesy of mastermind.
https://youtu.be/h9dVpnEmzRY

SierraMtns · January 05, 2018, 10:36:18 PM

I did more grinding today and polished the lower transfers and intake. I went down to 180 grit and then a rubber polisher. How smooth do you guys make?

Man these lower transfers are hard to photograph.

XP_Slinger · January 06, 2018, 08:41:14 AM

You actually want the intake and transfer passages to be textured not polished. Texture creates surface turbulence that prevents fuel from falling out of suspension and sticking to the port wall. Think of it like when you drive through thick fog and the moisture sticks to your windshield. Same thing will happen with atomized fuel in your ports and cause fuel to puddle. Someone chime in if I'm off on this but I understand it to be pretty standard practice.

NCFarmboy · January 07, 2018, 09:17:13 PM

I use 80 grit - 120 grit for intake. Whichever I have on hand.
Shep

EvilRoySlade · 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.

Rx7man · 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!

ehp · 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

XP_Slinger · November 21, 2018, 03:17:11 PM

I'll be tearing my 372 apart this winter to inspect the plastic caged bearings. I've got a good amount of run time on it now with the unlimited coil. I'm curious to see how the bearing retainers have held up to the higher rpm.

XP_Slinger · November 21, 2018, 03:19:37 PM

Wish I would've known you were at Boonville Ed, I'm only 45 minutes from there and it would've been great to meet you and shake your hand.

ehp · November 24, 2018, 01:42:56 PM

Ya my wife and I went and it was a good show . I have had zero crank problems or bearing problems but I do run 40-1 using what I think is oil . I will not be getting a new 572 now I donot think . I like the little light hotrod saws

XP_Slinger · November 27, 2018, 04:20:27 PM

Yeah I hear you on that. I haven't had any bearing issues with my saws either. The new 572 intrigues me because it's new, but I won't be trading in my trusty 372 to get one.

MG2186 · November 27, 2018, 04:29:12 PM

Quote from: ehp on November 24, 2018, 01:42:56 PM
Ya my wife and I went and it was a good show . I have had zero crank problems or bearing problems but I do run 40-1 using what I think is oil . I will not be getting a new 572 now I donot think . I like the little light hotrod saws

Ed do you still port saws or just your own?

ehp · November 27, 2018, 07:36:39 PM

mainly my own or a few friends close to me up here

MG2186 · November 28, 2018, 11:01:20 AM

Wow, just finished the whole thread. Very good read and super informative. I have a whole new respect for XT saws and will definitely look at them in a different respect. Ed's knowledge of these motors seems to be unmatched by anyone I've come across. Again good read and great job by all

barton174 · January 19, 2019, 07:04:56 PM

Well, I finally figured out the issue with leaning out and dying at idle after 10-15s! Looking at the IPL, with the machined bottom carb cover, you use only one of the gaskets on the top side of the diaphragm, but I have the stamped cover, and I guess you're supposed to use a gasket on top and bottom of the diaphragm, with said stamped cover. Added the second gasket and boom, idles great!

Mike

Wonka13 · September 07, 2021, 09:59:31 PM

Well, I think this thread has idled(😆) long enough!😁. Getting ready to dig into my 2021 372xt. I've watched all the YT videos you guys have put out, and many more...I'd say I've got a few hundred hours of research in on the 372/385/390....but, alas, I'm still a new dummy to saw modding. My plan, to start, is to cut out the strato-stuff on the AF holder & intake boot, in addition to doing a base gasket delete (current squish is ~ .045"). I'll see how it runs after that prior to going dremel mining on the cylinder...though I may reprofile at least the intake into more of a knife-edge while I'm fiddling...heck, I'll already have the dremel out and intake boot off after all😉😆. Any long-term feedback from you guys that have been running these saws, in various modified forms, for the last 5 or so years? Lessons learned, improvements made? Thank you for your willingness to share your hard earned knowledge!