572 updates

[andyshine77]

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.

Wanting more power is wanting more [emoji16][emoji111]

 

[dustinwilt68]

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]

Relortedly that was only on the early 681s and the supposedly fixed the issue. But I have seen plenty of 7900/7910 also have issues, so I would assume none are above having issues

 

[andyshine77]

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.

Lot more twist with longer stroke!

 

[Dub11]

Lot more twist with longer stroke!

Kind of reminds ya of a 300 6 lol.

 

[andyshine77]

Relortedly that was only on the early 681s and the supposedly fixed the issue. But I have seen plenty of 7900/7910 also have issues, so I would assume none are above having issues

Crank issues? I have not see or heard that with the 7900. Guys building 681's still like to Tig the crank pin. But yeah stuff happens.

 

[dustinwilt68]

Yes sir, I have, now those saws we're used and probably abused some also.

 

[andyshine77]

Yes sir, I have, now those saws we're used and probably abused some also.

[emoji106]

First time I've heard of any real issues with 7900 cranks, but I will take your word for it.

 

[huskihl]

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

Not certain. Maybe 10-15 grams.
The 385 didn't rattle apart as bad as a 390, and that's only 1mm bigger. Just thinking outloud is all

 

[dustinwilt68]

Odd the OE and XPW piston saws have less failures then the xtorq as well, I have always attributed it to the extra weight of the xtorq piston

 

[andyshine77]

Yeah sure seems like the heavier piston in the 372 X Torq was too heavy, especially if you wanted them to rev 13,500 or better.

 

[huskihl]

Yeah sure seems like the heavier piston in the 372 X Torq was too heavy, especially if you wanted them to rev 13,500 or better.

Mine was bought from a logger or tree guy. Made it 2 years before it locked up from bad main bearings. I bet there's quite a few 371's still kicking around running original bearings

 

[MustangMike]

I agree with all the comments here about the heavier pistons, and understand what is involved (partially because my brother is a PE).

So it amazes me that we can slap 460 top ends on 440s w/o any rebalancing, and they seem to hold up pretty well. As my brother commented, the bottom ends must be a bit over built to begin with.

 

[dustinwilt68]

I agree Mike, same with the Xpw topends and the 7910 series also. And the 281/288/394 all share the same crank as well

 

[Johnmn]

Jonsered 625/630/670
Husky 61/266/268/272
All share the same bottom end with zero issues. I have a 48-50 and 52mm version in red and black they all run differently yes but issues no.

 

[chipper1]

Wanting more power is wanting more [emoji16][emoji111]

That's right, and I want XP .

 

[MustangMike]

I’d still buy the 572 over the 462 despite it weighing marginally more. It’s a better all around package with better fuel economy and its smoother to run. It has enough power that if I need more... I just step up to a 90cc saw. Just my opinion. Not to mention the 572 is usually cheaper to buy than the other options in the class.

Like I said a while ago it likely depends on what you need the saw for. Mason's argument makes sense for felling and bucking (and mostly longer bars), but if you mostly drop yard trees, and have to do a lot of limbing, or you work out of a bucket like a lot of my Tree Guys, the lighter weight of the 462 will be appreciated, and in stock form performance is very similar. The 462 with a 20" light bar is very hard to beat in that arena.

 

[Dub11]

Jonsered 625/630/670
Husky 61/266/268/272
All share the same bottom end with zero issues. I have a 48-50 and 52mm version in red and black they all run differently yes but issues no.

I think they were over built in the first place, if you look at them saws they started out with full circle skirted pistons and seems to lose some material as they got bigger. Which probably counter balanced that.

I should weigh some pistons

Like I said a while ago it likely depends on what you need the saw for. Mason's argument makes sense for felling and bucking (and mostly longer bars), but if you mostly drop yard trees, and have to do a lot of limbing, or you work out of a bucket like a lot of my Tree Guys, the lighter weight of the 462 will be appreciated, and in stock form performance is very similar. The 462 with a 20" light bar is very hard to beat in that arena.

Whachu you talking about Willis?

This is a crank bearing, piston weight thread now. Ain't nobody got time for tree cutting.

 

[Willard]

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.

The 572 long 39mm stroke is a good thing .
Alot less side thrust on the piston skirt, that engine will go along time before failures.

 

[shadco]

That's right, and I want XP .

Fwiw

I would rather have XS.

.

 

[MustangMike]

The 572 long 39mm stroke is a good thing .
Alot less side thrust on the piston skirt, that engine will go along time before failures.

How do you figure??? I would think larger stroke would create greater side thrust, but the length of the rod and location of the pin would be significant factors in this also, so I would not pass judgement either way. Longer stroke means greater piston velocity and travel (but a lighter piston).