Been a minute

[cease232]

Took a break from chainsaw forums and tinkering. Still use saws everyday but had too many other things going on to play with them. Bought myself a new ms461 last week and got the bug again. Had this 026 I bought a couple years ago still on my bench. Top end was lightly scored so I decided to do some grinding.

Took .053 off the base

Set the squish with an OEM gasket

Widened the exhaust, intake and lower transfers.
Timing-
Ex 101
Tr 126
In 75
Now to cut the key, mod the muffler and reassemble.




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[drf256]

Did you cut piston and chamber flat, or did you just sand the shít outa the chamber with an old slug? Use a wood chisel to clean up the edge of the SB where it meets the chamber.

The lowers look good, but widening the intake side of them only added case volume for no real reason. That side won’t help flow.

Your exhaust roof is way too flat if I am seeing it correctly. Should be more of an arc and not a flat in the center with rounded edges kinda thing.

Bevel everything. I’d raise the uppers to 116-118 personally. If you don’t have a 90* tool you can use some type of disc.

 

[cease232]

Did you cut piston and chamber flat, or did you just sand the shít outa the chamber with an old slug? Use a wood chisel to clean up the edge of the SB where it meets the chamber.

The lowers look good, but widening the intake side of them only added case volume for no real reason. That side won’t help flow.

Your exhaust roof is way too flat if I am seeing it correctly. Should be more of an arc and not a flat in the center with rounded edges kinda thing.

Bevel everything. I’d raise the uppers to 116-118 personally. If you don’t have a 90* tool you can use some type of disc.

Thanks for the feedback Al.

I made a cutter for the chamber with the same radius as the piston.

I only widened the intakes a few millimeters and mostly on the exhaust side. Really just knocking off the corner.

Here is my exhaust. I pretty much left the factory shape. Just squared up the corners when I widened the port.

Move beveling [emoji3581]

I studied your RIchevy 026 thread and your transfers were at 123. Any insight on 116? That seems like a lot. I don’t have a 90* tool but have been wanting one for years. Maybe it’s time. I’ve never tried the cutoff disk method.




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[Nutball]

I'm not a fan of using a cutoff wheel.

 

[Lightning Performance]

I think the cutoff wheel works fine.

 

[cus_deluxe]

with a bunch of fartin around, the cutoff disc method sorta works on big cylinders. just gonna butcher that nice upper in ur pic doin it that way. ask me how i know...

 

[Sagebrush33]

I'll come here for my entertainment, before TV, any day.

 

[82f100swb]

Upper transfers are untouched in this one. 91/115/74, 0.0165 Squish. Base and band are cut.

Same saw, running the 3/8" 20" setup off of my 660, with the rakers way deep for this saw in some mostly frozen Poplar at -25c last winter:

https://youtube.com/shorts/n8rVp9sRo1w?feature=share

And in some not so frozen pine:

I really prefer the .325/16" setup, but I had to try the 3/8.

This saw also does not have a muffler mod. It has a stock 4 hole muffler cover, and a spark screen in place....

 

[drf256]

Thanks for the feedback Al.

I made a cutter for the chamber with the same radius as the piston.

I only widened the intakes a few millimeters and mostly on the exhaust side. Really just knocking off the corner.

Here is my exhaust. I pretty much left the factory shape. Just squared up the corners when I widened the port.

Move beveling [emoji3581]

I studied your RIchevy 026 thread and your transfers were at 123. Any insight on 116? That seems like a lot. I don’t have a 90* tool but have been wanting one for years. Maybe it’s time. I’ve never tried the cutoff disk method.




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Happy you didn’t take it the wrong way. Was meant to be constructive and not critical of your work.

If you kept the factory roof then you should be fine with it. On an 026, I widen and keep factory roof because it’s way too high already. The saw needs less exhaust duration. It does look like you cut into the roof, I kinda just blend it. I’ll look for pics.

I cut the chamber flat which allows me to drop the cylinder further than you did. Usually one can take around 65 thou out and just start to freeport. The bases on the jugs are usually around 240 stock, so they get real thin when you take some meat off. Never had one crack, even when I did 246 pistoned 026’s.

The 116 vs 123 question. It’s because of your numbers. I usually go with around a 78* intake floor on everything. So, keeping at least 40* of cranking compression, that puts me at needing a 118 or numerically higher upper transfer. Then there is blowdown, which I like around 15-18* on an 026 (and most other dual upper saw motors). So Jeff’s saw, IIRC, has a 105 ex roof and 16-18* 0f BD which probably is where 123 came from. I usually do 105/120 on these saws, and I can’t remember why I went 123. A bit more BD gives them a bit more torque, it could be why.

Being you’re at 101 ex and 75 int, 116-118 is where I think you’d have a sweet spot. If you want to mark the 118 on your jug and ship it to me, I’ll raise em for ya and ship it back.

 

[drf256]

Looks like you cut into the roof here.

Here’s one I did. The 2 jugs together are stock vs mofo. You should be able to see what I am talking about with blending the roof.

 

[drf256]

 

[cease232]

Happy you didn’t take it the wrong way. Was meant to be constructive and not critical of your work.

If you kept the factory roof then you should be fine with it. On an 026, I widen and keep factory roof because it’s way too high already. The saw needs less exhaust duration. It does look like you cut into the roof, I kinda just blend it. I’ll look for pics.

I cut the chamber flat which allows me to drop the cylinder further than you did. Usually one can take around 65 thou out and just start to freeport. The bases on the jugs are usually around 240 stock, so they get real thin when you take some meat off. Never had one crack, even when I did 246 pistoned 026’s.

The 116 vs 123 question. It’s because of your numbers. I usually go with around a 78* intake floor on everything. So, keeping at least 40* of cranking compression, that puts me at needing a 118 or numerically higher upper transfer. Then there is blowdown, which I like around 15-18* on an 026 (and most other dual upper saw motors). So Jeff’s saw, IIRC, has a 105 ex roof and 16-18* 0f BD which probably is where 123 came from. I usually do 105/120 on these saws, and I can’t remember why I went 123. A bit more BD gives them a bit more torque, it could be why.

Being you’re at 101 ex and 75 int, 116-118 is where I think you’d have a sweet spot. If you want to mark the 118 on your jug and ship it to me, I’ll raise em for ya and ship it back.

Thanks for the explanation. Really helped clarify the rational behind the numbers.

On the exhaust roof I just removed the plating. I find it easier to sand and polish that way.

I appreciate the offer but I decided to order the CC specialties right angle handpiece. Already got it all marked out. Got a bunch of other saws here begging to be ruined.


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[cease232]

Time to get to work


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[cease232]

Transfers at 118

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[drf256]

Did you lower the floor of the uppers also? They look huge.

I’d be interested to see where your piston crown is at BDC. Toss a ring in there and mark it or just take a pic if you can.

 

[cease232]

Did you lower the floor of the uppers also? They look huge.

I’d be interested to see where your piston crown is at BDC. Toss a ring in there and mark it or just take a pic if you can.

The top pic was my first attempt with the right angle. I put a little divot in the floor of the transfer so I just blended it a bit. The other side I was super careful and the floor was untouched.

Piston crown at BDC


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[Lightning Performance]

The top pic was my first attempt with the right angle. I put a little divot in the floor of the transfer so I just blended it a bit. The other side I was super careful and the floor was untouched.

Piston crown at BDC


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These pics even make them look like 110-112

 

[cease232]

These pics even make them look like 110-112

I triple checked it, checked the wheel and triple checked it again. I’ll go check again.


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[Lightning Performance]

I triple checked it, checked the wheel and triple checked it again. I’ll go check again.


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No bother... just don't see transfers that started out that low to begin with.
Nothing else looks out of whack.

 

[Lightning Performance]

Or high ports... depends on how you look at it.

What was your blow-down number?

Under 20?... I don't go digging for numbers and didn't check back again in the thread.