084 milling saw .... er, I mean, PROJECT saw

[mtngun]

The software you are using, is it really expensive?

MOTA is spendy. The current version doesn't support stratos, either.

Red is the anticipated build with the incorrect 1.69 case compression

Blue is the anticipated build with the correct 1.58 case compression. At least, it's correct going by the way that MOTA measures case volume.

As you can see, lower base compression is good for low end power. Higher base compression is good for high end power.

If I wanted to, I could regain the "lost" peak power by adding a couple of degrees intake duration, so it's not really lost.

 

[Mastermind]

The main reason I was wondering about the software is the Husqvarna 2101 I'm building. I can build a "normal" worksaw, or a screaming cookie cutter without any worries. I build one for torque, the other for rpm, by the difference in intake timing and/or raising the exhaust port, etc.....

As you and others have found, for a saw intended for milling these rules my not apply.

 

[mtngun]

Got the 084 mostly buttoned up but not quite done with chain brake, etc.. In the meantime, I checked timing with a full size degree wheel and here is how things ended up:

96 ATDC / 168 duration exhaust

122 ATDC / 26 blowdown transfer, measured with a thin wire. The thickness of the wire has to throw off the measurement a bit, I suspect blowdown is actually 25 or 24.

282.5 ATDC / 155 duration intake. For once I hit my target number. :msp_thumbup:

0.025" squish, exactly as planned.

6.47 : 1 swept compression ratio -- it might blow 145 psi ?

The piston top received a ceramic coating.

Then I found a big typo in one of my MOTA files, oops. Here is how it comes out with the typo corrected and with the actual build numbers.

Red is the actual build.

Blue is stock with muffler mod.

Violet is stock with restrictive stock muffler.

That is not much more peak power than my hi-comp 066, but more power in the mid range where you need it most.

Weather has not dried out nearly enough to go woodcutting, so no hurry on this build. Pic from my deck yesterday.

 

[Hddnis]

Looking good by the numbers. I standing by for the in the wood numbers too. Should be a real good milling saw with a long bar in wide fir.

As to your picture from the deck...
Gotta love all the snow we're still getting.



Mr. HE

 

[mtngun]

She's running ! Woohoo.

36" Carlton closeout bar from Bailey's. Not a beauty queen, but hopefully the old gal will be a workhorse.

It wouldn't idle worth beans when I first started it up, and just didn't sound right. Turned out the flywheel was on the wrong keyslot. It's hard to make heads or tails out of this tech memo, but I think it is saying that coils with 3 bolts use the B slot. My coil is the 1124-400-1308 with 3 bolts. Anyway, I moved it to the B slot and now it runs and sounds better.

Cold after 10 minutes run time. I had guessed it would blow 145 psi. Maybe it will eventually. If I hadn't done the pop-up, it would have only blown 120 - 125. Very low compression ratio in stock form.

The state won't sell me a woodcutting permit for another month yet because the logging roads are muddy, so for now all I can do is speed test it on a cant like I do with all my milling saws.

3/8 chain ground 40 hook, 0 tilt, and 2 top plate, similar to what Malloff recommended. 6.1 degree raker angle, 8 pin rim.

In case you are wondering why the nose rivit is missing..... this clearance bar started out as 404, but I had no intention of running it that way. I'd like to run 325 chain eventually, but there's no money in the budget to buy 325 chain right at this moment -- this project is already way overbudget. :msp_unsure: I had 3/8 milling chain on hand, so for now the 3/8 nose is held in place by chain tension. I don't think it will go anywhere, but if it does, I'll put a bolt in there, so the bar can be easily swapped from 3/8 to 325.

I've got to mill up new cants, so the speed results probably won't be in until tomorrow.

 

[Macclay]

Outstanding, great work:msp_thumbup:

 

[mtngun]

Made three 12 1/4" wide pine cants for speed testing. :msp_sneaky:

The 084 had been tuned by tach to 11,500 rpm WOT, but once I started cutting, it was obvious it was still pathetically rich, so I turned the H screw in 1/16 turn, without checking rpms. It was still blubbering a little in the cut, but not too bad.

This is with an 8 pin rim, which I assumed the 084 would pull easily.

1st pass -- 0.75 inch/sec

2nd pass -- 0.086 inch/sec

3rd pass -- 0.086 inch/sec

Average -- 0.82 inch/sec

That's exactly the same speed as my hi-comp 066 did with the standard WP 3/8 milling chain, plus I'm pretty sure the Malloff grind should cut faster.

Revs were only 7000 - 8500 in the cut, and it was surprisingly easy to bog. I'll retest with a 7 pin.

Today's test was disappointing, but bear in mind it's only got 15 or so minutes run time on the new rings, and it's still tuned a bit rich.

 

[mtngun]

Which should mill faster, my 084 or my 066 ?

Blue is the as-built 084.

Red is the as-built 066.

Peak power is the same (at 10,000 rpm, ignore the 12,000 rpm stuff cuz you can't cut at 12,000 rpm).

If you believe MOTA, the 084 has a broader powerband. Indeed, the 084 seemed willing to lug the 8 pin rim down to 7000 rpm, while the 066 - 7pin is useless below 8000 rpm.

But if the operator can keep them in their powerband, cutting speed should be about the same with either saw. If you believe MOTA.

 

[blsnelling]

I haven't followed the whole thread here so may have missed something, but your compression sounds way low. My 084 has a .042" popup and 170-175 compression. I have a MS880 here with no popup making 165 PSI compression and a squish of .023".

 

[Andyshine77]

My stock 084 has a bit over 150 psi.

 

[blsnelling]

Low compression would explain why it feels weak.

 

[RiverRat2]

Pulling jug tonight, pics to come.

Not sure about the filter screws, need to find an IPL and see exactly what is missing.

Send me a PM with your email Addy and I'll send you the IPL!!!

 

[mtngun]

Low compression would explain why it feels weak..... My 084 has a .042" popup and 170-175 compression. I have a MS880 here with no popup making 165 PSI compression and a squish of .023".

140 psi @ 4500' = 165 psi @ sea level

Compression will depend on compression ratio, which depends on chamber volume, which varies from jug to jug. This jug had a huge chamber. Even with the pop-up, the compression ratio was still modest.

Thanks for the offer RiverRat, but I found the IPL last year. :cool2:

 

[mtngun]

As mentioned in post #123:

6.47 : 1 swept compression ratio -- it might blow 145 psi ?

 

[mtngun]

Forgot to say thanks for the compression data, guys. You make me jealous.

Most of the time, after porting and popping, the best I can hope for is that I'll be able to cut as fast as a stock saw can cut at sea level.

 

[Andyshine77]

Mt I didn't know you were a mountain man lol. My 084 seems to be a good runner, some of the 084/880's I've ran were unimpressive. Do you use the trapped method to get your compression ratio? I hear it's the best way for piston ported 2 cycle engines.

 

[RiverRat2]

Thanks for the offer RiverRat, but I found the IPL last year. :cool2:

LOLOL!!!! wow I just read through this whole thred,,, and I just noticed it was started a year ago after readin this post,,,,

Im goin back to sleep!!!! Duhhhh!!!!!

 

[blsnelling]

140 psi @ 4500' = 165 psi @ sea level

Forgot to say thanks for the compression data, guys. You make me jealous.

Most of the time, after porting and popping, the best I can hope for is that I'll be able to cut as fast as a stock saw can cut at sea level.

Well that's a bummer. That stinks how elevation kills power like that. Glad that there's nothing wrong with the saw though.

 

[mtngun]

Retest with 7 pin rim.

0.87 inch/sec with 7 pin vs. 0.82 inch/sec with 8 pin.

Speed in cut was still only 7000 - 8000, though, and it still required a light touch to avoid bogging.

I tried leaning it out a bit more, and it sounded perfect to my ears, but there was no speed improvement.

For some reason it just doesn't want to rev in the cut. I'll try pulling the muffler screen and retesting. Can't think of any other simple fixes at the moment.

 

[Mastermind]

These are your numbers as of now. What were the stock numbers?

168° duration exhaust
155° duration intake
26° blowdown