572 updates

[andyshine77]

How many grams do you think a 2mm bore increase would affect piston weight? That's a real question, I am not being sarcastic. I respect your skill and knowledge

It's a huge difference. Not necessarily just in piston weight, but area/volume, pressures, drag, changes combustion properties, changes the differential between case and cylinder volumes, fuel system requirements, heat, the list goes on.

 

[Dub11]

It's a huge difference. Not necessarily in piston weight, but area/volume, pressures, drag, changes combustion properties, changes the differential between case and cylinder volumes, fuel system requirements, heat, the list goes on.

The have done it before with success.


And for any one wondering a 50mm bore would yield 76.5cc and a 52mm bore would be 82.825 cc

 

[Willard]

Also more vibration, like the old Stihl 066 with its P/C on a 064 crank. Different balance factor.

 

[andyshine77]

The have done it before with success.


And for any one wondering a 50mm bore would yield 76.5cc and a 52mm bore would be 82.825 cc

There has been successes and also major failures, it's not as simple as most make it out to be when you understand a little about engineering.[emoji111]

 

[Dub11]

There has been successes and also major failures, it's not as simple as most make it out to be when you understand a little about engineering.[emoji111]

I can imagine. I have an engineer at work that doesn't seem to realize this when it come to web presses and how poorly he under builds parts compared to manufactured units.

 

[TreeLife]

Seeing as how it would be a redesigned piston AND cylinder to properly accompany said increase of bore, as well as the bottom end having some beefy bearings...I'm sure its plenty feasible. Cooling area would be the biggest concern, but out the gate these saws arent running huge comp or wild ignition timing either.

 

[dustinwilt68]

This says to me that saw guys are never happy, always want more.

 

[TreeLife]

This says to me that saw guys are never happy, always want more.

Nah, I love my 572 personally. I dont and wont need a bigger saw...but I have a 281 should I have a need

 

[dustinwilt68]

Personally I just want to see how these saws hold up over a few years of real world useage, to me that will be the bigger deal.

 

[N8TE]

This says to me that saw guys are never happy, always want more.

Ha.. you're probably right. For me though, if I've got a biggish saw in that 6-7 hp range and a smallish saw in the 4-5 hp range....I'm happyish

 

[huskyboy]

I like the fuel economy of the 572 as is... while others are fueling up there modded 372’s, 390’s and whatnot... I’m still getting the timber on the ground... what saw is cutting faster now ? The money saved over time with buying fuel is something to consider too.

 

[MustangMike]

For the factory to offer it in a larger bore, likely the piston, cylinder and crank would all be a little heavier.

 

[andyshine77]

Seeing as how it would be a redesigned piston AND cylinder to properly accompany said increase of bore, as well as the bottom end having some beefy bearings...I'm sure its plenty feasible. Cooling area would be the biggest concern, but out the gate these saws arent running huge comp or wild ignition timing either.

It may vary well work, but again what you described is an extreme oversimplification of how things actually work IMHO.

When you've seen computer modeling, ultra high-speed filming, have spoken with and worked with GOOD engineers, as a non engineer your whole perspective changes.[emoji111]

 

[andyshine77]

For the factory to offer it in a larger bore, likely the piston, cylinder and crank would all be a little heavier.

There's no such thing as a small change!

 

[chipper1]

This says to me that saw guys are never happy, always want more.

You must be including yourself in this group of unhappy guys.
Okay maybe not lol.

Personally I just want to see how these saws hold up over a few years of real world useage, to me that will be the bigger deal.

Wasn't you the guy who just had a 550 ne ported.

 

[Dub11]

You must be including yourself in this group of unhappy guys.
Okay maybe not lol.

Wasn't you the guy who just had a 550 ne ported.

Don't forget his xpw saws lol.

 

[andyshine77]

Just thinking to myself here. Okay let's say the bearings are big enough to support a top bigger top end. How about the big end bearing? If that's not large enough what happens to the crank? Now if the crank has to change, let's say the bearings are still big enough, but now they spin out of the case [emoji44]. This has happened. Now we also have the Solo 681, it has a 1mm longer stroke than the Dolmar 7900. The 681 is known to have the crank go out of phase, you don't hear that with the 7900, and the 681 has I believe similar size bearings as the 572.

Just me sitting here bored thinking and rambling.[emoji4][emoji111]

 

[dustinwilt68]

I don't include porting in the wanting more category, that's just maximizing what you have. Wanting the factory to create things that don't exist yet is "wanting more" category.

 

[Dub11]

Just thinking to myself here. Okay let's say the bearings are big enough to support a top bigger top end. How about the big end bearing? If that's not large enough what happens to the crank? Now if the crank has to change, let's say the bearings are still big enough, but now they spin out of the case [emoji44]. This has happened. Now we also have the Solo 681, it has a 1mm longer stroke than the Dolmar 7900. The 681 is known to have the crank go out of phase, you don't hear that with the 7900, and the 681 has I believe similar size bearings as the 572.

Just me sitting here bored thinking and rambling.[emoji4][emoji111]

I was thinking about that big end bearing too especially with it having a 39mm stoke you know thats putting some funk on it. That's 1 more mm than a 395 and 3 more mm than a 372.

 

[Dub11]

I've also have wondered is a more "balanced" strato piston would help any. It would be heavier but it would have to help with it rocking in the bore a little I think.