Paul Bunions
ArboristSite Member
Wait...a 72 cc saw uses more gas than a 92 cc saw?
Bar Size for Chinese MS660 Clone?
- Thread starter Paul Bunions
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camel2019
ArboristSite Guru
Something ain’t right there
I've never really timed the 660 and it does have a bigger tank but the 372 is a gas hog. It has a big bore kit in it so it's more like 75-80 cc. It runs very well.
My G660 definitely uses more fuel than my G372XP, which has also been an awesome saw. I run a 24" Forester pro bar and fc chain on it and it pulls nice.
Well now I'm curious. I'm going to have to do some kind of fuel consumption test. I just know when I use the 372, I put gas in it more often than any other saw I have.
Novice4Rent
ArboristSite Lurker
I have a similar experience. My first saw was an Echo CS590, which worked flawlessly for about a year until I made the mistake of trying used, synthetic 10W-30 in the oiler system when bucking a 28" oak on our property. The oiler self-disassembled; I was able to get it fixed under warranty, but still needed to deal with the oak. The Blue saw maker had a Black Friday sale on pre-assembled 92cc powerheads, so I bought one to deal with the oak. Once I realized the incompatibility of Echo and Stihl bar attachment designs, I purchased a 28" bar for the Blue saw (and a skip chain). It made bucking the oak child's play.
In the three years I have used the clone, several things have indeed failed. The muffler spontaneously loosened, dropping hardware. (I found blue loctite holding the bolts on, not the red stuff.) It got replaced with a dual-port unit. It also developed air leaks between the cylinder and case when pushed hard in bucking applications. While repairing the base gasket the first time, I swapped in a Duke's high compression piston, and got good results- the saw seemed to run more cleanly. But the second time, I replaced the PC assembly with a Hyway 56mm Nikasil cylinder and a popup piston. This worked well enough, with serious torque, until the cylinder hold-down bolts sheared off during a dieseling-runaway while bucking an ~30" tulip poplar. I replaced the apparently defective bolts with Grade 8 hardware from my local Ace (at $0.85 each, I find it hard to understand why anyone would use inferior bolts in this application!!) This machine also suffered from a bar alignment issue, and the chain adjuster mechanism was terrible- and the case was machined so that it wouldn't accept a Hyway adjuster replacement! I replaced the clutch with a Hyway unit as a precaution. (The advice came from afleetcommand on Youtube.)
It hasn't been all bad, however. The clone ripped through a 36" hickory and bucked >70 rounds from it, before doing the same with a similar white oak last summer. Other bucking duties were routine for it. Were it not for the metallurgical failures, I would plan to keep using the thing- it starts well enough now that I use a Husky (not Stihl) decompression valve. But the bolt failures made my family beg me to bury it in the compost pile. In contrast, the Echo has been more reliable, especially when pushed to what should be it's limits, and beyond. If Echo still made a 90-cc class saw, I would be first in line to buy it! In short, look at afleetcommand's videos if you are committed to this line of action. While a decent mechanic, I am stopping before I get maimed.
Huh. I've run saws for a number of years, and never used any Loctite (blue or red or green) on the muffler bearings.
Never had that happen either, but I don't "push hard." The saw should self-feed. If not, I generally check the chain for cattywampus...
Novice4Rent
ArboristSite Lurker
Sorry for the poor wording on my part. By pushing hard, I meant WOT in 30+" hardwood (nearly always hickory) beyond the point that I saw smoke rising from the chain, for round after round in the summer heat. I had an issue with the wood possibly swelling and trapping the bar/chain during cutting. Wedges helped, but didn't 100% fix the problem. Getting a chain grinder for better chain prep later helped in subsequent efforts. And the worst issues came when using a full cutter, not the skip chain I mentioned earlier. The saw motor seemed willing, but the chain itself often stretched with the heat, hanging below the bar at times despite apparently correct tensioning before cutting. (My notes tell me that these efforts preceded the development of air leaks each time. And as ever, YMMV.)
Eventually, better technique, chain prep, and allowing the chain to cool between rounds helped dramatically reduce the multiple issues.
HansFranz, what saw(s) are you using?
Jason1980
ArboristSite Member
I have one I ported I can pull a 52inch bar with a ripping chain on mill
A (mostly) Chinese 660 and a real MS361, mainly, though I do have some others currently.
Charlie Coyote
ArboristSite Member
As to the bolts shearing after you replaced the cylinder and piston; did you torque to factory spec or just rife on them? Expansion of the metal alone can shear a bolt that's out of torque specification.
Charlie Coyote
ArboristSite Member
My new G660 PRO has about 8 tanks of fuel through at 40:1 straight hitest/VP Racing 2 stroke full synthetic and it's coming into its own with each refueling. Right now I have an Oregon PowerCut .063 bar and chisel full comp and installed the Farmertec high output oil pump that's necessary t run longer bars. It pulls strong through 40" knotty pine rounds. It's a heavy package that uses waaay lots of fuel; like twice as much as my Echo CS620PW 27" that's my go to for almost everything. I got the G660 PRO to be dedicated to milling big logs, not as a firewood saw. I think that it's set in and it's now my mill saw for the big logs. My 52" bar for it arrives today. That's needed to maximize the 36" mill to produce 32"-33" wide boards and slabs. I like the 27" (28") on the 620, as it's a lighter package, pulls strong even when buried and uses half of the fuel. I like a bar slightly nose heavy, but as heavy as the G660 PRO powerhead is, with the 36" it's too heavy for me to use for long for a firewood saw. The 28" or 24" would be more suitable IMHO. I bought the Echo early Spring this year after I toasted my old Husqvarna 359. I considered the 590 at first, but after extensive reviews and videos I decided to up my base $220 more for a truly professional quality and I'm glad I did; though I'm not bucking hardwoods and that will up the ante.
Novice4Rent
ArboristSite Lurker
I was playing "Monkey See; Monkey Do" when following Afleetcommand's youtube videos. No accurate torque spec taken, but red loctite employed, with a good twist. The bolts had loosened up spontaneously "as delivered", so I assumed anything I did would be an improvement. The Ace Hardware Grade 8 bolts seem to be holding up pretty well. I still intend to replace this Blue saw with a white and orange unit.
Charlie Coyote
ArboristSite Member
Well, I can see you're bound to learn by your experience, then you'll know. Good luck on removing any threads when fixed with red LocTite; that is permanent thread locker. You'll read in the torque spec attached that the cylinder bolts are to be 7 ft lbs. That's not as tight as they can be rifed down. As the saw comes up to operating temperature metal expands. If the cylinder bolts are too tight, then something has got to give. Best to always use new bolts and if you're really worried about them loosening blue LocTite will keep it fixed. I've not had a bolt loosen with LocTite 243 and it takes some effort to remove. Good luck on the learning. I've found trial and error to be wasteful of time and money. There's a lot of information available to me when I search. It saves me both.
I've had my G660 since May and I've run around 7 gal of mix through it at this point. Most of that was done while running a 42" bar with full skip 3/8 chain while milling some large (+48") oak logs in half so that I could get them winched up on a trailer and hauled to a mill. The rest was either running the same bar while bucking some of those logs that didn't got to the mill, or with a 28" bar and full comp chain while noodling the large rounds down so that I can lift them onto a splitter manually. The stock oil pump was week so I replaced it with a hi output pump from Hyway pretty early on. Stock pump struggled to keep up with the 28" bar which is uncommon even for a Farmertec. The hi output pump keeps up with the 42" bar. Not sure I'd want to go longer though. If I were going longer on a mill, I'd probably opt for adding a DIY auxiliary oiler out at the tip. Keep in mind that I have absolutely ZERO experience with a chainsaw mill. I only say this based off of the vast wealth of infallible knowledge I've gleaned from the internet....
General rule of thumb, if the screw has loctite on it, go to your dealer and get an OEM replacement. Same goes for any nylock nuts. Also throw away the stock e-clip on the drive shaft, or at least check that it has the right temper and flexes during removal/install instead of bending. Skipping this step can cost you a clip, drive bearing, clutch, and potentially an oil pump.
General rule of thumb, if the screw has loctite on it, go to your dealer and get an OEM replacement. Same goes for any nylock nuts. Also throw away the stock e-clip on the drive shaft, or at least check that it has the right temper and flexes during removal/install instead of bending. Skipping this step can cost you a clip, drive bearing, clutch, and potentially an oil pump.
