Husqvarna 372xp with 268 "popup" Piston , Husqvarna 372 Build Tips & A quick Review Of CST.

THIS is one of the better Husqvarna 372 build video's I had done. BEFORE turkey oven...but the info is still valid today in fact MORE so as the OE's are getting rare and Husqvarna X-torq's are more common set of bones to build from
Have to catch up on work, so stuck a little of that "Work" in here. KIND of "effed" Up on the 562 for the discussion as I had basically cleared most of the information before realizing I had a dead saw with possibly interesting stuff for the video....a SHARP CST type will catch that. But for demo and discussion.....its "OK".
Then to the fun stuff, the popup concept with a piston like that 268 gives me material to work with on the PISTON so I don't have to deck the cylinder to get where I need for a pop up. A HUGE advantage to that concept. I didn't explain it as clearly in this video. I will do a better job in the one I'm editing now, PART 2.
Cover some basics when trying to evaluate used parts, actually some survival tips I take for granted....so while this is a review of things, It's been a couple of years since I've done this so its time....and this time with the chassis for THIS year at HTSS, the 372.
Big saws ... are big. I can't deal with them much any more. The 372 is the best of all worlds for me, simpler technology, easy to work on and a gazillion of options for building these...AND last but not lease, aftermarket support.
Plan to throw some Huztl/Farmertec saws in the discussion as for many that is the ONLY option they have the skills to work from to get into the 372 chassis..Original Edition style...:)
Going to be an interesting year. As I look at the saw prices climb out of sight. these "junk pile" builds become even more relevant. Blending OEM on saws like the Holzfforma (Farmertec) G365....gets folks with out the special skills and tools for the cases a platform to work with....a interesting concept we will explore as time goes on.
BUT my true interest is OEM, and also even back to the 200 series OEM.s certainly the Original Edition 372 are way more interesting than the "X-Torq" Morphodites and the emission saws that require the Husqvarna Mother Ship to setup. Or the Stihl counterparts.

[@sunbear1973]

Great information and still love watching your older videos

[@michaelmeyers1827]

I really do enjoy your u tube feeds I have never watched one so much. Thanks

[@brendonhauschild9763]

Thanks for the awesome pt1 build you blow my mind on your skill and knowledge level. information which you can take to any two stroke engine.

[@climbe4422]

There was a lot of good information in this video Walt .thanks.

[@markjoudrey7036]

Awesome.Looking forward to part 2.

[@antoniomorgado5304]

Nice vídeo Keep going Mr. Walt! Thanks for the good fun!

[@krustysurfer]

Another Great Video Big Guy! blessings and aloha to you

[@ericrice4156]

Great information Sir, you definitely have my attention!!!

[@johnhudson4493]

Good work, answered a few questions I had. Now get out on that ZRT!

[@smithtradfallning]

You gonna like that 268 pop up.

[@brendonhauschild9763]

Can you show us how you attached the piston to to your mandrel in the lathe .thanks Walt

[@afleetcommand]

kzbin.info/www/bejne/fabYdpSHr9qfjsk

[@colebones]

Now would you do a pop-up with a base gasket delete? Does that pop-up part clear the cylinder then leave you with the same squish and therfore more compression. But then can that cause predetination?

[@rncboy2]

Very curious as to if a husqvarna 262 48mm piston will work in the 365 48mm cylinder. Same wrist pin size or smaller?. If it will work I'm sure the wrist pin hight is taller? Maybe?

[@andrewotero1972]

You have a lot of great videos out there my question is on the 660 clones the farmer Jones saw I had a glance of the porting you did on it when when you combined the transfer ports does that mess with crankcase pressures

[@afleetcommand]

Not in a negative way enough to matter, I think what folks need to understand is everything is a compromise. To fixate on one issue misses the point that its an entire system...:)

[@andrewotero1972]

Thanks a lot for the quick response got a couple of saws that I'm playing with want to try to use am parts for the builds and trying different ways of porting the little finger part that you put on Farmer Jones does it give it a little bit more RPM And how are the sawsdoing in the field been following that series for a while just curious

[@davemartin9774]

@afleetcommand I started running my new 372XP original edition clone at 32:1 as you said you run yours. Man o man were you right. When I tore it down just to look at the piston and cylinder and they were coated with a thin sheen of oil just like yours were! I'm sold! Also going to run 32:1 in my McCulloch 4318A 72HP drone engine in my gyrocopter N521LW. I wouldn'rust my life to running 50:1 anymore now that i've seen the difference... Thank you sir you might have saved my life (from a low altitude engine out). And I don't care if the EPA doesn't like me running 32:1 Im doing it regardless... Heck I burn 100LL AKA 100 octane low lead in the gyro anyways and thats what 99% of all general aviation uses in piston engines. 100LL also doesn't contain ethanol either and it works really good in the 372XP by the way (if you have an airport close). Should work really good with your souped up pistons and cylinders!

[@afleetcommand]

Just keep track of carbon build up in that steady state application, some of the two stroke oils burn different...AND some of the Paraffin based oil need to be at the thinner rations...:) I'm running an ester based synthetic or semi synthetic. :) Especially in an air craft! Please keep track

[@jameschang8122]

if it brakes then just put a new top end in it they are not that hard to change out i have done it 4 times on saws and they are still running to this day

[@MrLukas797]

hi,,what is compression now????

[@rncboy2]

Just wondering. Is the wrist pin offset .020 or .030 for the 268 then a 372 piston causing the bottom of the skirts to be .020 or .030 higher then a 372. Reason I'm asking is wouldnt it cause the intake port timing to be way off.

[@afleetcommand]

No...:) Often when building those saws the desired "numbers" for intake are in the 78-80 degrees BTDC Figure roughly .018 -.020 of change in the skirt or port floor is about a degree. And Stock it's not uncommon to see that number in the 75-76 degree's BTDC. So actually that change moves things in the right direction...

[@rncboy2]

Makes sense now still a bit new with 2 strokes. I was asking because of a stihl 029 46mm piston milled to a popup for a husqvarna 51 or 55 jonsered 490 590 46mm topend. The piston wrist pin placement I'd have to get measurements on again to let you know what they are but they are roughly about .030 difference. That's the reason I was thinking one wouldnt work because those for the 372 and 268 look off set as well. I have not tried it with the 51 yet so I'm not sure it would work yet... Fire wood saw. I know they are different then a 372 in sizes.

[@afleetcommand]

Just remember each saw design responds differently to changes in timing numbers. While those numbers I mentioned work on the 372, they may not on a different design.

[@rncboy2]

I can say now I've done it with a husqvarna 51. Using a stihl ms290 super 46mm piston. Cut .022 with a base gasket an 1184 I'm right at .037 squish. Wanted a bit more but its actually for my uncle as a fire wood saw. Has a hyway closed port cylinder . I did open the transfers, matched the transfers to the cases. Opened the exhaust port a bit didn't change port timing from port just from the 029 ms290 piston. No idea how much its changed I never did check it with a degree wheel. I do know the piston skirt is raised about .035 or so give .005 or so. It does have really really good throttle response. When I did finally get the chance to get some run time on it it suprised me. It had 4 heat cycles before it put it to the wood. Wasn't expecting it to have good power with a 20 inch bar and chain combo. Forgot to mention I did balance the stihl piston to the original single ring oem 46mm piston have to take 3 grams more off to compensate for the other ring that's added. I new I wouldn't loose power through that and keep the life of the crank higher then just slapping it together without checking. OEM pist by itself is 57 grams (for the old style and for the new style 51 saws they are 54 grams) the stihl 46mm AM piston is 62 grams. If I wouldnt of checked it I dont think the connecting rod bearings would hold up. That might be something to look into with certain builds just a side note. I know you dont build 50 51 55's much but could be helpful with other builds. Maybe something to test and see if it helps or hurts power in the saw.

[@KensSmallEngineRepair]

Walt, what did you see for compression?

[@afleetcommand]

Didn't check. Might after it breaks in a bit. Its going to be in the 190-200 range would be a guess. A bit more than I like for a work saw, its a "play" saw.

[@geoffclark9820]

Walt, just a quick question. I'm not trolling I think it's a valid question because I have tried to find a torque spec for the cylinder and haven't been able to find it.Granted I haven't looked to hard. My question is, why would the flywheel torque be more important vs torquing the cylinder? I'm a heavy duty mechanic by trade and find it interesting that no one seems to be torquing the cylinder yet most people do the flywheel. My thinking would be opposite. The flywheel mates to the tapered crankshaft and is pulled in by the nut with a fair amount of surface area and stress, so in my mind the goal is to get it tight but not tight enough to break the flywheel. I think 26 ftlbs is probably a very good torque value to torque the nut too. However the cylinder in my mind would be more critical being magnesium its obviously softer like aluminum, so over tightening would pull threads and under tightening would create vac leaks. Any suggestions, ideas or theories? I'm used to working with mechanical engineers so by all means don't hold back. Thanks Walt. Great video.

[@afleetcommand]

No idea

[@geoffclark9820]

@@afleetcommand sorry Walt I asked the question quick then I figured I would edit it and see what input you had. Any suggestions?

[@afleetcommand]

Usually torque isn't as much about the materials being held together, its about stretch in the fasteners. :) Most "screws" have recommended torques based on thread, diameter, length, and materials. I'm certain there are a bunch of tables out there for grade 8 5mm - .8 cap screws :) I suppose a video on fasteners and vibrations might be fun for tech geeks. Me? I crank on those pretty hard, but focus on doing a cross pattern more than the actual torque. I might start in the 10lb/ft range I guess and see if you snap one..:)

[@geoffclark9820]

@@afleetcommand Thanks for the input. Very aware of a torque range. CAT for instance recommends a 3/8" cap screw be torqued into cast iron 35ftlbs, the same fastener but in aluminum you basically knock off 10-15ftlbs. Detroit uses the same idea as CAT, however CUMMINS uses a torque then turn to yield spec. The reason I asked my question was because I purchased a new 365, had one before and loved it. The new one was having what I thought was carb issues. I took it back to the dealer, they told me it ran fine and gave it back. I eventually put a vacuum on it diagnosed the cylinder was lifted and the cause was 3 out of 4 fasteners were loose and pulled threads. I called the dealer I bought the saw at and was told I voided the warranty by working on it my self. So in the end I helicoiled it. Seems to be holding so far, didn't torque it though.

[@afleetcommand]

@@geoffclark9820 So my question is was that saw from the factory or did it have a different top end. In 10 years on the saws I've never seen the cylinder screw holes get stripped...wonder what that deal was! Most of my time with engineering was with Cad/Cam with a focus on CNC and integration of dissimilar systems...then on to software specification and support. But My FIRST job out of college was as an engineer for a fastener company. Not going to say which one. First project was testing elastic stop nuts and their degradation after multiple uses....talk about boring! The old grass growing joke applies here! Had to build base line data with a variety of faster systems, different materials etc. ...and yea the torque was obviously a part of that deal. Never forgot the lessons learned there. Could do a video on that as there was a lot of clarification that happened during that "Siberia" experience. Short time at the company, in retrospect one of the most enlightening and useful experiences as Fasteners are not going away, software and all related things are in a constant state of flux......15 almost 20 years of experience not useful today....1 year at that "nutty" place is still very relevant. :) ...as an aside, when the theoretic "stretch" of a fastener isn't going to happen because of materials being "fastened", other devices begin to show up like thread locker and nylon lock nuts etc. Always a clue. Sometimes just things like hard washers or flanged heads...but the variations are endless so as you may have seen by now there are a gazillion different design criteria..would be some big books to get all of them. Manufacturers hopefully have done their homework and testing, right? I haven't yet used anything but feel on the chainsaw cylinders BTW..I trust the feel more than a set number, especially on an older saw where they parts could have been apart a few times. Hasn't failed me yet either. I can get the torque values I guess and post them. But from the the sound of your description a lot more than just torque values are at play in that movie. BTW

[@nkcwilliams]

Walt, Is this saw running yet? We cant wait to see the next video.

[@afleetcommand]

Yup, usually takes a week or two for videos to get built..:)

[@SCOTTISHPREPPERVARIETYCHANNEL]

whats the assembly paste you use ?

[@afleetcommand]

Paste? You asking about the Three Bond 1184?

[@SCOTTISHPREPPERVARIETYCHANNEL]

@@afleetcommand yes sound good stuff for builds