Any parts that can be swapped from metals to plastics? I know the flywheel is at least one...

[Cerberus]

I can't stop thinking of reference I heard to a plastic flywheel for the 660, would be curious to learn more about it and any other swaps, or mods, that can be done for things like:
- reduced weight of powerhead;
- reduced reciprocating weight (I know heavier flywheel "keeps momentum going" so arguably would help w/ max power, if I understand correctly, but a lighter flywheel means quicker responsiveness of the engine to your input on the throttle)

Any other areas to get bona fide weight savings, if any exist, would be greatly appreciated (am kinda wishing I went lightweight on the bar, thinking "I want strength, the power of this thing, w/ the big dogs on it, will let me put real high force on that bar" and the non-lightweight was chosen explicitly for being stronger (not cheaper) Now I'm comfortable having a lightweight bar, as I'm far better at not getting it pinched, but am 'stuck' now w/ the 25" Rollo-O bar (which is awesome just not especially light, otherwise A++ bar for sure -- I did find it odd to see green IE "safety" markings on the bar, thought they were for chains only, unsure how / what kind of bar is "yellow/not anti-kickback", can't see how the bar can have much influence..)

Thanks for any insight, am trying to build an "ultimate 'smaller' 25" 660" and "at the finish line" doing detail stuff now (probably going to make it a fiberglass "sled" / undercarraige shield ;D )

 

[Cerberus]

Oh and the 2lbs muffler...
I suspect the "bearclaw" style of pipe-mufflers would come in at 1lbs, max, so I'm VERY keen to get-on with that (as I believe it's an awesome next-step for saw performance, our lack of pipes is what has us at such massive disadvantage to rest of 2-stoke world!), I know it's not 'tuned' insofar as acoustics but tthat doesn't mean you can't ensure maximal pressure of good charge at the flange, **and** have it "sucking" exhaust from the cylinder at the same time.....

BUT I have no idea how to weld, and - before I can even ask on my local F.Book group - I'm here hoping someone can ttell me how to ask, IE do I need a TIG, MIG or other type of welder? I'd basically be requesting: "Looking for someone who can weld-together 5 pieces of already cut-to-fit steel together for me, it needs to be airtight welding but is fine if 'overdone' I'm happy to grind/cleanup myself" but I'm no sure if I should be getting galvanized steel piping, regular steel piping....REALLY hope I don't have to get SS piping for this, I know it'd look awesome but not trrying to spend $$ or time on aesthetics (though my new build is darn sexy if I say so myself ;D )

Thanks for any insight/guidance on finding a local to weld (steel/galv stteel/etc) tubing, I know i can make it just how I want, have them weld it, then have a far more ideal muffler than my currentt approach (sandwiching "plates" in-between front&rear halves of the 660 muff assembly They serve to redirect the exhaust pulse right back at the exh.flanging, creating a swirl/vortex in there, only a beta version but works well, however I expect these "bearclaw type pipe mufflers" are the best!

 

[MustangMike]

I always like the Stihl E bars - much lighter and less expensive than the ES bars, but they seem to be no longer available. There should be many used ones out there if you lo0k for them.

The green bars generally have smaller nose tips than the yellow bars, resulting in less kickback. However, I think the larger tip bars generally have less rolling resistance. While E bars in 20" are green rated, the 24" ones were yellow rated.

You won't notice the difference in the weight of a saw from a lighter piston, but it will run smoother and (all other things being equal) will last longer. Usually, the OEM pistons are the lightest out there, but there are exceptions. Some of the Meteor pistons are also very light but may have heavier wrist pins. Often you can reduce weight by using an OEM wrist pin, but be careful, some pistons have a different length pin. OEM piston pins are generally tapered (on the inside) toward both ends, while AM piston pins are usually uniform thickness.

 

[smokey7]

I use hydraulic tubing for my pipe style mufflers. Ive used conduit and copper fittings too if i am using silver solder. If using dissimilar metals silver solder works very well. Ive never tried aluminum and steel.

 

[Cerberus]

I always like the Stihl E bars - much lighter and less expensive than the ES bars, but they seem to be no longer available. There should be many used ones out there if you lo0k for them.

The green bars generally have smaller nose tips than the yellow bars, resulting in less kickback. However, I think the larger tip bars generally have less rolling resistance. While E bars in 20" are green rated, the 24" ones were yellow rated.

You won't notice the difference in the weight of a saw from a lighter piston, but it will run smoother and (all other things being equal) will last longer. Usually, the OEM pistons are the lightest out there, but there are exceptions. Some of the Meteor pistons are also very light but may have heavier wrist pins. Often you can reduce weight by using an OEM wrist pin, but be careful, some pistons have a different length pin. OEM piston pins are generally tapered (on the inside) toward both ends, while AM piston pins are usually uniform thickness.

Is it fair to say that it's really more about chain than bar, though? When trying out Stihl B&C gear this past year, I can't say I noted any difference in their bar but the RS33 chain is worlds above anything I've used (and I use it exclusively on full-tooth chains...are any of their climbsaw chains as-big an upgrade as their RS33 is for big saws?)

Piston weight....I was surprised to find zero #'s on piston weight in-relation to rotation speed, I mean in a fixed setup where you make the only variable piston-weight you should be able to demonstrate just how significant it is, but instead it's just "yes of course less weight = less rotating force at TDC&BDC = faster operation & more efficient operation" but by how much??
There's also a serious gain in bottom end displacement, seems 660 pistons are around 100g and I've seen videos of guys simply removing casting flash & creasing and reduce weight ~5g....that is ~2CC's!
For the 660 though the lowers are fed, in part, through the windows of the piston especially at BDC so opening them up is almost a necessity in some contexts (ie if you're trying to feed larger ports, like if you just over-ported things ~15% )

Had 'slop' in between the wristpin bosses on the piston I ended up using, would be interested in hearing 'max acceptable slop' because of the 3 pistons I had I used the one w/ most slop (not for that reason, obviously, in spite of that) and have been using the saw, figure the nature of the engine would basically 'force' symmetry here (for instance even a "tighter fit" still has 1mm+ of play, it's hard to fathom a saw running with the pin 1mm off-center at operational RPM's!)

 

[MustangMike]

Bar weight will make a big difference on some saws. For example, heft a 362 Ver II with a 20" ES bar and it will be very nose heavy ... heft the same saw with an E bar (or ES Light) and it will balance well.