Olympyk 980 Woods Port

[mtngun]

Did the pin locations limit the intake port width -- or do the rings even enter the intake port ?

Was the OEM port timing conservative, like my 980 ?

How did you mod the mufflers on your Olys ? Did you gut the insides ?

I'd never seen a 999 until you posted your pics. Four Paws has it, eh ? If I ever bump into him .......

Thanks for the pics.

 

[Gypo Logger]

Did the pin locations limit the intake port width -- or do the rings even enter the intake port ?

Was the OEM port timing conservative, like my 980 ?

How did you mod the mufflers on your Olys ? Did you gut the insides ?

I'd never seen a 999 until you posted your pics. Four Paws has it, eh ? If I ever bump into him .......

Thanks for the pics.

The # I have on the stock figures of the 999 are as follows:
Ex 27mm
In 65 mm
Tr 32.5 mm
It's been so long since I had work done to them and 3 builders worked on them I don't recall.
If I was any kind of a builder, I would have wrote more stuff down than what I did.

Gypo

 

[mtngun]

Wow, that is a monster. The saw, I mean.

It's a shame we can't get them here. You'd think it would appeal to CSM'ers looking for an affordable alternative to 880's and 3120's.

 

[KMB]

How did you mod the mufflers on your Olys ? Did you gut the insides ?

I did a bit of a mod to the innards of my 970's muffler. I'd like to get rid of more of the pipe, but I can't get my rotary tool with the cutting wheel inside any further.

I'd also like to add another port/pipe. Maybe have someone weld a pipe below the existing one.

I'll be watching to see what you come up with.

Kevin

 

[mtngun]

Thanks for the muffler pics, Kevin, you saved me the trouble.

That is an interesting muffler design, is it not ?

The question is, did Emak actually "tune" the internal pipe, or is it just some random thing ?

Yes, it is very difficult to get inside the muffler and cut that stuff out.

I'm thinking to gut the muffler and add a second port. Or perhaps, a larger single port.

It would be nice to have spark screen, too. Right now my Oly is not necessarily legal on public lands.

Without a dyno, it's anyone's guess whether removing the internal pipe will be an improvement.

I wish Four Paws were still around so I could pick his brain.

 

[KMB]

mtngun, your welcome for the pics. I should have did some test cuts before and after I had cut the pipe too see if it made a difference.

If a fella really wanted to get at the innards of these mufflers, he could cut it in half (front and rear halves), gut it, and then weld it back together. I don't own a welder or know how to weld. I've thought about drilling a hole on the other side of the muffler and screwing on one of those Husky deflectors, but the clearance to the plastic cover is my concern (and I don't think I'd like the way it would look).

Yep, Josh (FourPaws) knew his way around these Oly's. A good guy to talk to.

Kevin

 

[Stihl Crazy]

Your right about cutting the cover. Had to do that on my 165 to clear the Husky deflector. The 165 does not have the louvers like your 970. Like your cover better.

 

[mtngun]

Each 0.010" squish is 0.54 CC.
.
.
.
Estimate UCCR to achieve 165 psi, compared to 140 psi at 9.2 UCCR.

UCCR/9.2 = 165/140

UCCR = 10.8

Chamber volume required for 10.8:1 UCCR is 7.4 CC.

OK, pop-up time.

I measured the chamber profile with solder, and wrote a CNC program to follow the profile. Let's see if we can meet our chamber volume goal with only a 0.020" pop-up, cuz I don't want to cut any more than I have to.

On my previous pop-up, I got dinged for having a sharp angle, so this time all angles are gentle. In fact, the pop-up is so gentle, it's almost invisible.

Using the 6-jaw to hold the piston.

Bird's eye view.

Gently sloping angle, following the profile of the chamber.

I was having a tough time operating the calipers and the camera simultaneously, but just take my word, the remaining land was 0.118" - 0.119".

Thrice I measured the zero squish chamber volume with the new pop-up -- 6 CC, compared to 6.7 CC stock.

Total chamber volume @ 0.025" squish = 6 CC + 2.5 * 0.54 CC = 7.35 CC

I needed 7.4 CC and got 7.35 CC instead.

Looks like that's as far as I'll get tonight.

 

[parrisw]

Nice work MR!! Looking real good.

I love the look of that 6jaw.

 

[Gypo Logger]

Sorry I didn't get out my 980 as I promised. I got a job yesterday as a diamond drillers helper, work 7 pm to 7am 7 days a week for 6-8wks and start tonight.
Will try to get it out though between shifts.
John

 

[mtngun]

As discussed in a previous post, it was decided to go with a 0.020" pop-up, and 0.025" squish.

How does that change the port timing ? I used the model engine news calculator to predict the port timing.

Here's a summary:

Here's the problem: tightening the squish decreases exhaust duration, while dropping the jug increases intake duration. The result is 151 exhaust and 153 intake -- that doesn't sound like a balanced combination.

I can't do a darned thing about the increased intake duration, but it's easy to increase exhaust duration by raising the roof of the port. The tentative plan is to raise the roof 0.7mm to bring duration back up to 156 degrees.

I am new to this port timing business, so I'm not confident about tweaking the timing. Anyone have any thoughts or suggestions, bearing in mind that this is a work saw that will sometimes see mini-mill duty ?

 

[blsnelling]

Isn't that a pic of Big Dave Neiger?

 

[Gypo Logger]

Isn't that a pic of Big Dave Neiger?

Yes, that would be Big Dave at Eric's place in Ohio.

I take it back, I had to go to the shack to get work clothes, so I took some pics of the 980.
Gypo
photobucket not working.

 

[mtngun]

Gypo's muffler mod.

Gypo's modded filter cover.

Looks to be in nice shape. What's with all the snow ?

 

[Gypo Logger]

As discussed in a previous post, it was decided to go with a 0.020" pop-up, and 0.025" squish.

How does that change the port timing ? I used the model engine news calculator to predict the port timing.

Here's a summary:

Here's the problem: tightening the squish decreases exhaust duration, while dropping the jug increases intake duration. The result is 151 exhaust and 153 intake -- that doesn't sound like a balanced combination.

I can't do a darned thing about the increased intake duration, but it's easy to increase exhaust duration by raising the roof of the port. The tentative plan is to raise the roof 0.7mm to bring duration back up to 156 degrees.

I am new to this port timing business, so I'm not confident about tweaking the timing. Anyone have any thoughts or suggestions, bearing in mind that this is a work saw that will sometimes see mini-mill duty ?

I found some addition numbers for the 999 if it helps for comparison.
The ex was raised 10 thou and the intake was lowered 2mm. The transfers were left stock at 32.5 mm. I'm assuming these were Dave's #'s but can't be sure as three builders were into it already.
Gypo

 

[mtngun]

In an earlier post, I discussed raising the exhaust port a little to compensate for tightening the squish and to complement the unavoidable increase in intake duration. The plan was to raise the exhaust 5 degrees, or about 0.7mm, for 156 degrees duration.

It ended up getting raised more like 1.3mm. Oops, my bad. It's also 15% wider now, but still has at least 0.100" of skirt on either side.

Exhaust before porting.

Exhaust after porting.

Here's the predicted timing, bearing in mind these computer calculations are sometimes a few degrees off.

If the timing really works out that way, I'll be content. 153 intake / 160 exhaust is quite sane compared to my 660 jug.

That's all I got done tonight.

Next task will be widening the intake. I haven't decided how much to widen it, but leaning toward 15%, same percentage as the exhaust was widened, to keep things balanced. Any thoughts ?

 

[Gypo Logger]

Looks to be in nice shape. What's with all the snow ?

We still got a bit of snow up here, but melting fast. You got me anxious to play with my 980. It's pretty heavy for an 80cc saw, but it's sure well made.

You're way out of my league with the math, but from what I see and understand you should have a good runner when you're finished.
Gypo

 

[mtngun]

We still got a bit of snow up here, but melting fast. You got me anxious to play with my 980. It's pretty heavy for an 80cc saw, but it's sure well made.

It's snowing here as I type.

Yup, the 980 is heavy and doesn't really have a niche. I plan to use mine mostly for mini-mill duty. It should be perfect for that.

 

[Gypo Logger]

It's snowing here as I type.

Yup, the 980 is heavy and doesn't really have a niche. I plan to use mine mostly for mini-mill duty. It should be perfect for that.

My 980 seemed to get up and talk. I took it to a GTG in Ohio. I'll try to get the times from that race.
Are you in B.C? near Falkland? there's a Snake and Salmon R there as well.
John

 

[mtngun]

My 980 seemed to get up and talk. I took it to a GTG in Ohio. I'll try to get the times from that race.
Are you in B.C? near Falkland? there's a Snake and Salmon R there as well.
John

Idaho.

I meant to ask you, besides adding the 2nd exit port, did you do anything else to your 980's muffler ?