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

[parrisw]

So far, I haven't widened the ports. I could, but bear in mind this will be a milling saw, not race saw. I want to enhance power at 8000 - 10,000 RPM, not 13,000 RPM.
That's as far as I got tonight.

The bar, which was supposed to ship separately, still has not arrived. For a while, the seller was saying he had simply forgotten to ship it, but kept promising he would ship it. Today he said he shipped the bar shortly after shipping the saw (2 1/2 weeks ago). He seems to have a hard time keeping his story straight. :censored:

Wide ports are good, just don't raise the port. You'll want low and wide for a good torquey saw.

 

[little possum]

Very nice work

 

[Jacob J.]

Thanks for the backup. Yes there is allot of air going in and out of that big bastid. I don't know how the theory totally works, you'll have to ask TW maybe, he's the one that told me once, he told me what might happen with my 395 with how much compression it has, and well he was totally right.

I've seen the bigger saws break the mounting ears off the cylinder more often when they're pumped up to high compression than the littler saws. It comes down to volume and the amount of stress being laid to the components (and the amount of material in those components) in the saws.

 

[mtngun]

I've seen the bigger saws break the mounting ears off the cylinder

Wow. I wish I had a saw that had that much compression.

 

[parrisw]

I've seen the bigger saws break the mounting ears off the cylinder more often when they're pumped up to high compression than the littler saws. It comes down to volume and the amount of stress being laid to the components (and the amount of material in those components) in the saws.

Wow, that's allot of stress. I'm a little worried about my 395, it was at a hair under 200psi before breakin. Its ever so slightly slow to come to idle when its hot, but hardly noticeable. But it sure runs!!

 

[mtngun]

I ground the lip off the roof of the exhaust port, except at the peak of the arch, which was left alone so as not to increase the exhaust duration.

No widening, either, just polished. I've got a ways to go to catch up to TW in the polishing department, but it's an improvement over OEM.

You know I was tempted to to port it, but ....... it's an expensive jug to experiment with, and porting usually shifts the power band to higher RPMs, so I took the conservative approach and merely cleaned up the ports a little.

Back later with a port map and the predicted timing numbers.

 

[mtngun]

Now that the crank is out of the case, it's easier to measure the con rod length. I'm calling it 75 mm.

The port map after the very minor mods.

Intake floor is now very flat, as per your suggestions. Plus, removing the protruding lip lowered the floor a few degrees.

Exhaust roof used to have a pronounced arch, but now much less so after removing most of the protruding lip. I have nothing against arched ports, I just didn't like that lip.

The numbers for the lightly modded cylinder and pop-up piston:

Con Rod length = 75 mm (previous calculations assumed 80 mm)
Deck height (center wrist pin to top of piston) = 24 mm
Piston height = 46 mm
Exhaust duration = 167 degrees (same as OEM)
Intake duration = 143 degrees (versus 133 OEM)
Blowdown = 23 degrees

As always, port map predictions may be off a few degrees compared to degree wheel measurements.

That's pretty much how I expected the timing to fall out. Intake duration still seems conservative, but...... you can always take off more metal later, but it's hard to put it back.

 

[luvsaws]

Looking good

 

[Andyshine77]

Stock my 084 has 155 psi I'm betting your rings were worn, I bet you'll see 165 psi or better.

 

[blsnelling]

My 084 has 170-175 PSI with a .042 popup. That left me with .097" above the top ring.

 

[mtngun]

Stock my 084 has 155 psi I'm betting your rings were worn, I bet you'll see 165 psi or better.

That's the best I've heard so far on a stock 084.

I'd love to have 165 psi, but don't think it is going to happen with the low (9.1:1) compression ratio.

I never tested this one stock since it was not in running condition when it came into my hands -- rings were frozen, starter would not engage, etc..

This is what I am going by to estimate PSI, based on only a few data points.

 

[Brmorgan]

The 084 I picked up a while back hits just a bit over 150, and it's barely broken in - the horizontal mill marks on the piston are still plainly visible. If I were at sea level it might get around 160.

 

[mtngun]

Parts are starting to trickle in. The Caber rings showed up, so I was able to CC the chamber with the pop-up piston -- 11.2 CC pop-up vs. 13 CC OEM.

That, plus setting the squish, will put the UCCR at 9.3:1 and could, in theory -- if the rings seal well -- produce 145 - 150 psi. That would be great.

The oil output hose was brittle and cracked. I have the replacement -- but how on earth do you get the old hose out ? Is there a trick ? It seems to be stuck in there pretty good.

 

[blsnelling]

The oil output hose was brittle and cracked. I have the replacement -- but how on earth do you get the old hose out ? Is there a trick ? It seems to be stuck in there pretty good.

Heat is your friend.

 

[mtngun]

Heat is your friend.

Oven and dental pic ? How hot ?

 

[blsnelling]

Oven and dental pic ? How hot ?

I'd use a heatgun.

 

[leeha]

I'd use a heatgun.

+1
Heatgun is the way to go.


Lee

 

[mtngun]

I wish I had a heat gun, but that's pretty far down the wish list at the moment, well below the ultrasonic cleaner.

A little hit with a propane torch softened the old hose enough to pry it out with a small screwdriver.

The propane torch didn't seem like a good idea for installing the new hose, though. Instead, I used lots of lube, pounding, prying, and cussing. It finally let me have my way with it.

Also made a 60mm sleeve for the modular mandrel.

Not much else I can do until more parts show up, not to mention the missing bar.

 

[mtngun]

As mentioned previously, the starter wasn't working when I received the 084. The rotor had wallowed out where it holds one pawl, letting the pawl get cockeyed, and creating just enough friction to jam things up.

A new rotor 1124 195 0400 was ordered from that ebayer in Everett, but I actually received 1124 195 0401. It was similar, but not quite the same. Good thing I have a lathe, because I had to open up the rotor's bore.......

......the new rotor was also thicker than the old one. Good thing I have a lathe ! ! ! (sorry for the crummy pic)

At last, the new rotor fit my 084. But....... the old pawls didn't fit the new rotor. The fit was too tight and created too much friction. What to do ? I ended up swapping my 066's pawls into the 084, and the 084's pawls into the 066. Both sets of pawls fit perfect in their new home.

So ends another simple task that should have taken 15 minutes but actually took 3 - 4 hours. :hmm3grin2orange:

 

[parrisw]

As mentioned previously, the starter wasn't working when I received the 084. The rotor had wallowed out where it holds one pawl, letting the pawl get cockeyed, and creating just enough friction to jam things up.

A new rotor 1124 195 0400 was ordered from that ebayer in Everett, but I actually received 1124 195 0401. It was similar, but not quite the same. Good thing I have a lathe, because I had to open up the rotor's bore.......

......the new rotor was also thicker than the old one. Good thing I have a lathe ! ! ! (sorry for the crummy pic)

At last, the new rotor fit my 084. But....... the old pawls didn't fit the new rotor. The fit was too tight and created too much friction. What to do ? I ended up swapping my 066's pawls into the 084, and the 084's pawls into the 066. Both sets of pawls fit perfect in their new home.

So ends another simple task that should have taken 15 minutes but actually took 3 - 4 hours. :hmm3grin2orange:

ha ha. Nice work as usual. I think I have the proper rotor that would of worked out for you. But looks like you had more fun that way.