Olympyk 980 Woods Port

[Meadow Beaver]

Snow? What's with this snow talk? It was 80 degrees here today.

 

[Gypo Logger]

Idaho.

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

Not that I can recall as it was 04 when I worked on it, but I did leave a screen in the second muffler port though.
It may look nice though with just a larger tube coming out the existing port such as 3/4 copper elbow. The 088 stock jungle mufflers were designed this way, but not available in North America.
John

 

[mtngun]

Width of the inlet port width was increased 15%, same % as on the exhaust. Inlet height was left alone.

OEM transfers were fine and dandy, so I'm done porting.

After supper, I'll make a base gasket and start on shaving the base down to set squish.

 

[mtngun]

Gasket made of manila folder, 0.011" thick.

Making 52mm sleeve for modular mandrel.

No place to put live center on jug.

Scrap piece of aluminum bridges spark plug hole.

Shaving jug to dial in 0.025" squish.

Port timing checked by degree wheel:

162 degrees exhaust duration
151 degrees intake duration
20 degrees blowdown

I'm mad at myself for raising the exhaust more than intended. I might drop squish down to 0.020" to drop the exhaust duration down to 160. I'll have to think about that.

Next big task will be modding the muffler.

 

[parrisw]

Gasket made of manila folder, 0.011" thick.

Port timing checked by degree wheel:

162 degrees exhaust duration
151 degrees intake duration
20 degrees blowdown

I'm mad at myself for raising the exhaust more than intended. I might drop squish down to 0.020" to drop the exhaust duration down to 160. I'll have to think about that.

Next big task will be modding the muffler.

Really nice work! I'd drop the jug to .020" squish, but I don't think 2° in duration will make much diff.

I like your idea of the mandrel. What kind of plastic is that?

 

[blsnelling]

If you want to go down to .020 squish, don't hesitate. My 084 is perfectly fine there. My 066 only has .017 with a factory gasket. Again, no problems.

 

[mtngun]

I like your idea of the mandrel. What kind of plastic is that?

UHMW. It's cheap, but very soft, and messy to machine. It does work OK, you just have to be careful not to let it get dinged up.

It's very slippery, too, but so far I haven't had any problem with the jug spinning on the mandrel.

If I had to do it over again, I would either use a harder plastic like perhaps delrin (more $$$$) or aluminum for the sleeves. Aluminum sleeves would still be cheaper than an all-aluminum mandrel because you only use 1/3 as much material.

 

[parrisw]

UHMW. It's cheap, but very soft, and messy to machine. It does work OK, you just have to be careful not to let it get dinged up.

It's very slippery, too, but so far I haven't had any problem with the jug spinning on the mandrel.

If I had to do it over again, I would either use a harder plastic like perhaps delrin (more $$$$) or aluminum for the sleeves. Aluminum sleeves would still be cheaper than an all-aluminum mandrel because you only use 1/3 as much material.

Ya, I may just stick to the solid alu mandrel's, so far I've made 2, now got to go another for the 371. How would you do alu sleeves? It would be a waste if ya had to buy solid alu to make a sleeve? Can you buy thick walled alu tube?

 

[mtngun]

If you want to go down to .020 squish, don't hesitate. My 084 is perfectly fine there. My 066 only has .017 with a factory gasket. Again, no problems.

+1

I normally set up my saws at 0.020".

This one I deliberately planned on 0.025", just so I'd have a little wiggle room to dial in compression, etc..

I'm glad I gave myself some wiggle room.

 

[mtngun]

Ya, I may just stick to the solid alu mandrel's, so far I've made 2, now got to go another for the 371. How would you do alu sleeves? It would be a waste if ya had to buy solid alu to make a sleeve? Can you buy thick walled alu tube?

Well, bear in mind the sleeves only need to be as long as the cylinder. I made my sleeves 4" long just in case I ever get a monster milling saw, but 3" long would probably suffice 99% of the time.

Point being, 48" of aluminum bar will make a lifetime supply of 3" sleeves.

I started with solid 2 1/4" rod. Set it up like an assembly line, cut them to length, drill the hole, bore to a snug fit on the steel mandrel, and then mill the key slot. The OD is not turned until the need arises.

Yes, it did take some time to make them, but you need some practice on the lathe, don't you ?

 

[parrisw]

Well, bear in mind the sleeves only need to be as long as the cylinder. I made my sleeves 4" long just in case I ever get a monster milling saw, but 3" long would probably suffice 99% of the time.

Point being, 48" of aluminum bar will make a lifetime supply of 3" sleeves.

I started with solid 2 1/4" rod. Set it up like an assembly line, cut them to length, drill the hole, bore to a snug fit on the steel mandrel, and then mill the key slot. The OD is not turned until the need arises.

Yes, it did take some time to make them, but you need some practice on the lathe, don't you ?

Yes. practice? ha ha ha. ya just a bit. I'm learning, getting ok at it, made some decent stuff so far, its all fun though.

 

[mtngun]

Port timing checked by degree wheel:

162 degrees exhaust duration
151 degrees intake duration
20 degrees blowdown

I'm mad at myself for raising the exhaust more than intended. I might drop squish down to 0.020" to drop the exhaust duration down to 160.

Shaved a little more off the base, aiming for 0.020" squish but ended up at 0.023" instead.

160 degrees exhaust duration
154 degrees intake duration
22.5 degrees blowdown

I'm happy with those numbers, but they are not explained by dropping the squish only 0.002". Perhaps yesterday the TDC wasn't dialed in perfectly and threw the numbers off ? Today I was extra careful setting up the TDC pointer.

Darned degree wheels -- too much human error. I like the computer method better.

 

[parrisw]

Shaved a little more off the base, aiming for 0.020" squish but ended up at 0.023" instead.

160 degrees exhaust duration
154 degrees intake duration
22.5 degrees blowdown

I'm happy with those numbers, but they are not explained by dropping the squish only 0.002". Perhaps yesterday the TDC wasn't dialed in perfectly and threw the numbers off ? Today I was extra careful setting up the TDC pointer.

Darned degree wheels -- too much human error. I like the computer method better.

Those numbers sound good for a work saw. That's about the numbers I'm going to use on the 371.

 

[mtngun]

Started on the muffler mod.

Port matched the muffler gasket and muffler entrance.

Removed the 5/8" ID pipe. Easier said than done.

The inner baffle does not appear to be restrictive so it stays.

Now there is a big rectangular hole where the 5/8" outlet used to be.

That's as far as I got tonight.

Next task is to make a deflector that will bolt on. Yes, bolt on, so a screen can be sandwiched between the deflector and muffler. That'll keep bugs and debris out and make this saw legal on public land.

 

[PLAYINWOOD]

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

ropes, switchback or mountain goats?
either way,impressive.

 

[Gypo Logger]

ropes, switchback or mountain goats?
either way,impressive.

Nice pics of Falkland. That's supposed to be the biggest Canadian flag in the west. I remember getting chased by a couple of bears there on my ATV! What a riot!
John

 

[PLAYINWOOD]

Didn't know about the flag bit, just thought it was cool at 70 mph. You can see it for 10 minutes but wasn't sure what the heck it was until I zoomed in at 12 power.
Should be a law about pic'n and driving.


a mile past Falkland all the mountains are burnt to a crisp,just brush. Must of been a fire recently.
Nice part of town, not very green because its still early spring but I love how it widens a few miles down the road into the city of Vernon.


I'm pretty sure the Okanagon could become home.We'll see

 

[Gypo Logger]

Didn't know about the flag bit, just thought it was cool at 70 mph. You can see it for 10 minutes but wasn't sure what the heck it was until I zoomed in at 12 power.
Should be a law about pic'n and driving.


a mile past Falkland all the mountains are burnt to a crisp,just brush. Must of been a fire recently.
Nice part of town, not very green because its still early spring but I love how it widens a few miles down the road into the city of Vernon.


I'm pretty sure the Okanagon could become home.We'll see

Ya, there was a big burn in 06 I believe. More in the lower elevations. There's lots of cedar, fir and pine still left though.
John

 

[les-or-more]

Is the combustion chamber centered or offset in the bigger saws?

 

[mtngun]

Crude homemade deflector. Spark screen from old 066 muffler.

Side view.

Testing fit on saw. Barely cleared brake lever, so had to do some more cutting, hammering, and welding.

Still a few minor chores to do -- paint muffler, carb kit, leak test saw. Otherwise, the major stuff is done and I'm just waiting on rings from the guy in Greece.