Relevancy of Husqvarna 570 and 575xp loggers junk saws

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I had an old loggers junk 575xpg laying around for a while now and I finally decided to see if I could make it into something decent and usable for myself. I am in want of a bigger old man saw basically, that starts easy, has low vibes and decent enough power to pull a bit longer bar if need be. As of this writing, there's not a lot of support left for these saws, there is however some left for its close cousin the 576xp. Here's where we get into the fun part. While there may not be a huge difference between the two saws running them, the 576xp does have an improved lower transfer system which is the main difference between the two. This could be an advantage as I plan to port this saw, so it could pay off dividends later if I could make a 576xp cylinder work on the 575xp chassis. Question is will it work and be a legitimate saw when finished?
With my search engine locating me a reasonably priced new OEM 576xp top end and having to pull apart the crankcase anyway to replace the frozen crank with one from a near new 570 along with one fly side case half as long as I was at it to eliminate the repair on the old. I have the tools from Husqvarna already here for disassembly as well as assembly. So, might as well give it a go and see where it takes me.
The hole patterns of the top ends are the same along with everything else but the lower transfers. Here's how that story unfolded....

 

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Here's a visual of both top ends with the gaskets to a fro for comparison.

 

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First thing was to put case halves together and place locating studs in the upper deck so 576xp gasket can be placed.

 

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Tracing with a marker shows what needs to be removed.

 

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Attacked with a reciprocating saw gets it roughed out.

 

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Epoxy is going to replace the voids.

 

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A sharp flat chisel took care of any flash.


Another go with the marker for final finish.

 

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Used porting tools to get the finished shape.

 

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There you have it folks, all ready to accept the "updated" 576xp top end. I think now you can see why it's not just a plug and play operation. It's also not for every situation either. If this were just a simple top end swap, this probably would have never came to be. Also, for folks that have the tooling to work on the cases. But, for the person that just happens to tick all those boxes like I just happened to, it may be something you would care to try.

 

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This is as far as I've gotten, so for those that want to see the end product will have to wait as this is something I do in dribs and drabs in my spare time, as well as acquiring the necessary parts to complete. When that day comes, I will do a follow up.

 

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One more thing to note, the case alignment pins are loose in the 575xp side case and not snug in the replacement 570 case half. Allowing the cases to go out of alignment at the cylinder base. My plan is to A, grease the case gasket and B, dab some threadlocker on the pins when installed and C, bolt on the cylinder just prior to the final tightening of the case bolts. While this is a rare thing to encounter, it needs dealt with or leaks can be had from either the misalignment or the breakage of a case gasket when it shifts.
(Greasing the case gasket is nothing new, or even a trick, I learned it from Husqvarna repair manuals.)

 

[hacskaroly]

There are still a few of these at work, both the 575 and 576s. I found out the hard way too that the cylinders don't just swap...so made due with what I had and got a 575 and 576 working with another 575 in my shop waiting to be worked on. I had two Stihl 362s (mTronic and carb) along with two Husky 357s from work jump in line, but they are now all up and running and out the door. I had a 571 I worked on yesterday and found it has an air leak, but the next one in line is the other 575. I kind of like the 575 and 576s, they seem to have a decent amount of power for their size.

 

[David Young]

A sharp flat chisel took care of any flash.
View attachment 464455

Another go with the marker for final finish.
View attachment 464456

Is that a porting chisel?
Nice thread thanks for taking us along so far. Was there a power change between the 575 and 576 I wonder it it was for better sealing? I ran a 576 at a GTG I could not believe how smooth it was in the hands only draw back in my opinion was it was slightly heavier than a 372.
Do both jugs have similar stock porting numbers? If I remember they have crank stuffers. Would the stuffers fit on a 372 crank?

 

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Is that a porting chisel?
Nice thread thanks for taking us along so far. Was there a power change between the 575 and 576 I wonder it it was for better sealing? I ran a 576 at a GTG I could not believe how smooth it was in the hands only draw back in my opinion was it was slightly heavier than a 372.
Do both jugs have similar stock porting numbers? If I remember they have crank stuffers. Would the stuffers fit on a 372 crank?

Well, I use it to scrape gaskets off on saws, some get ported, so, maybe?

The Husqvarna 576XP specifications are as follows:

• Engine: 73.5cc, 5.7 hp
• Weight (powerhead only): 6.6 kg (14.5 lbs)
• Recommended bar length: 16-28 inches
• Fuel tank volume: 0.7 liters (1.48 US pints)
• Oil tank volume: 0.4 liters (0.85 US pints)
• Max rpm 13,300

575XP
5.4 HP @ 9,600 rpm
14.9 pounds
13,500 rpm max

570
4.9 hp @ 9,600 rpm
14.6 pounds
13,300 rpm max

372XP
5.6 HP @ 10,200 rpm
14.1 pounds
13,300 rpm max

Design changed for better flow up through the transfer ports, so an improved design, best I can tell.

Don't know on the rest.
I can measure the ports to the squish band and see if the 575xp and 576xp are similar or not and get back to you.
I do have a set of stuffers and can eventually check them out for other fitments as the opportunity's present themselves.

 

[chipper1]

Don't think it's gonna be a legitimate saw, sorry .
As was said, the 576 was a crazy smooth saw. I remember the first time I ran one with a new x-cut chain in some pine, it was all I could do to not hit the ground, couldn't tell it was even cutting if not paying close attention.
Nice work.

 

[Stump Shot]

Don't think it's gonna be a legitimate saw, sorry .
As was said, the 576 was a crazy smooth saw. I remember the first time I ran one with a new x-cut chain in some pine, it was all I could do to not hit the ground, couldn't tell it was even cutting if not paying close attention.
Nice work.

570 and 575xp were smooth as well. I hope my illegitimate creation will be too.

 

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For the enquiry minds...
The timing of the two seem to be very close to the same for now, I will get back with more details later.
The stuffers from a 575xp absolutely DO NOT fit on a 372xp crankshaft like they should. Yes, it will loosely lay over the crank lobes but, will not slide on the butterises on the side of the lobes where the bearing stops at. Which I'm okay with, as it keeps me from tearing apart a saw put together not that long ago.