My 026 project

[brock1994]

Also how are you cleaning it?

 

[jeremyc]

Not finished with it but I’ve gotten most of the transfer off.
I am cleaning with acid on a q tip and sanding with 400 grit. When I started I could feel the ridges I. The cylinder with my fingernail but it is getting very smooth now. The pictures make it look worse than it is.

 

[blsnelling]

I see no transfer left in the cylinder, just scratches in the lining.

 

[jeremyc]

@blsnelling that’s what I though too. Do you think I should sand the cylinder more to blend the scratches or run it how it is ? Will I have issues with this much scratching in the cylinder ? Most of the scratches are below the exhaust port. I’ve done a few rebuilds like this before and usually just work it until the transfer is gone and it feels smooth.

 

[blsnelling]

As long as it's smooth, run it. Don't try to sand all the scratched out.

 

[RedneckChainsawRepair]

I just did one of them too that was lean scored.

This is cleaned by hand and flapper wheel. Smooth as can be and could run as is.

But I add a final step now. Crosshatching last pic.

 

[jeremyc]

Update on the project. Got my new meteor piston in today so I dove into porting the cylinder. I’ve done some minor port cleaning and smoothing on previous rebuilds but never been this aggressive.
So far I have just widened the exhaust port, blended the lower transfers down and toward the intake and smoothed the intake port. Just working on getting the ports shaped how I want them and then I will add the chamfer when I’m finished.
Also did the muffler mod the other day.
maybe @blsnelling will chime in with his expert opinion on the cylinder.
I am not sure what to do with the intake port. I smoothed it out but haven’t actually worked the cylinder opening area at all. Need to take some better measurements because the ring ends are really close to the intake port.

 

[blsnelling]

Make sure your exhaust port walls are flat from cylinder to flange.

Why did you widen the lower transfer ducts?

I recommend laying out all skirt widths and ring end locations before grinding on anything.

I like to make the floor and roof of the intake much flatter.

Have you measured port timing to know where you are?

 

[jeremyc]

Thank you for the input.

I thought I had read that widening the lower transfers was a commonly recommended thing to do along with smoothing out the lip, maybe I botched the job by doing that. ?

I don’t have a degree wheel to measure the port timing, and so far I have not touched the bottom or top of the exhaust port opening to prevent changing the timing.

I will try to figure out how to lay off the ring end locations tonight if I get some time.

 

[blsnelling]

The only thing typically done to the lowers is to remove the lip. I think you're getting confused with widening the uppers. You haven't killed anything though.

But you do have a degree wheel. Size it to your flywheel and glue it on with just a couple dabs of super glue. Make sure to center it.
http://www.tavia.com/free_degree_wheel.html

 

[jeremyc]

Ok you’re probably right about getting the Lowes and uppers confused. I have been reading the “porting 101” thread and most of the pictures don’t work so I was just trying to visualize what was being discussed there I pictured it meaning opening the lower transfers toward the intake port to help the intake charge flow into the transfer. Great info but it would be better with the pictures that’s were originally attached

I will set up the degree wheel tomorrow and see what my numbers are.
Is the wheel zeroed at tdc or bdc? Im assuming I should post measurements of exhaust/intake open, close and duration ?

 

[drf255]

Did you figure out why the original cylinder failed yet? The last thing you wanna do is run a saw with a new ported jug and make it score, all of that work will be in vain.

Have you figured out how you’re gonna adjust squish yet?

My guess is you’re at 96 Ex, 126 transfers and 72 intake. Around there. Software exists to use, in lieu of a timing wheel, and it’s pretty accurate.

http://www.torqsoft.net/piston-position.html

Don’t widen the lowers, and whatever you do, don’t grind out the intake side bump inside the tunnels.

Report back what you find.

 

[blsnelling]

You want measure where the exhaust and transfers open ATDC at the top of the port and where the intake opens BTDC at the bottom of the port.

 

[jeremyc]

Ok I will get the degree wheel set up at lunchtime today hopefully.
I installed the piston and cylinder this morning and without the base gasket it was hitting the roof and would not turn. I installed the base gasket and measured squish with solder/micrometer and it is right at 0.019-0.020 so that’s perfect from what I understand.
Thanks for all of the constructive advice guys!

 

[jeremyc]

Ok so i printed the degree wheel and glued it to the flywheel, removed the keyway from the crank and zeroed the wheel as best possible with a stop in the cylinder.
Here are my numbers

Squish 0.019
Exhaust 96
Transfer 118-119 but it’s kind of difficult to see
Intake is 68.

@drf255 about the reason why it scored in the first place, at the moment I am blaming that on the old carb that was replaced before I got the saw. I did a thorough inspection of the rubber parts and did a vacuum and pressure test and everything appears healthy at this time. I’m guessing the previous owner was running it with a poor tune or bad carb diaphragms when the lean condition happened. I will be able to tell if it’s not right when I get it running. I have rebuilt many saws and am familiar with carb tuning and what is right and what’s not.

 

[blsnelling]

That's not near enough intake for my liking.

 

[jeremyc]

Ok thanks Brad. I was reading some of the other 026 threads and some port timing discussion trying to find what guys are running.
I was reading where mastermind said he removed some of the piston skirt on an 026 to get the intake duration where he wanted it because it would require dropping the intake too much. Thoughts on that ?
Also, anybody have opinions on what I should do with the squish on this saw? Seems like some guys are sanding the band and dropping the base gasket to get more compression, but my squish seems pretty good at the 0.019 mark.?
I understand the way the 026 cylinder is shaped there are gains to be had by removing the rim around the edge and doing a gasket delete.

Any tips or tricks on how to layout the piston skirts and ring ends in the cylinder ?

Any numbers on what I should shoot for/stay within for the intake and exhaust ? I’m sure you get tired of newbs like me asking all these questions. Open to any input or opinions you guys have for me.

One more question guys... I have read some of you are just running a single ring for rpm gain... is that really a thing in a Work saw ?

 

[drf255]

You can scrape the small squish band out with a wood chisel, then apply adhesive backed sand paper to the old slug and sand the band area to match the piston.

You may be able to sand 20 out and lose your gasket. Watch for a ridge where the chamber meets the sidewall, this can again be scraped out with a chisel.

The only reliable way to measure the transfers is to drop a ring in the cylinder and mount over piston. Turn the saw over to what you think, remove jug and see where the ring falls vs the tranny. Use a pick. It takes trial and error.

I cut the squish bands flat on a lathe and take .060 out. I cut .043 off the piston dome flat and cut around .050 off the base. No gasket.

I’m usually at 105/126/72-4 that way (why my numbers were off above). You won’t get your exhaust that low without the extensive machine work, but you will still have a fine running saw.

Try Ex where it lands (likely 98), 118 uppers and 76-78 on the intake floor. Be careful on the intake floor, as a little goes a long way.

 

[blsnelling]

Cutting the piston skirt had perfectly acceptable. I would do that are re-shaping the intake port.

I almost always ruin a single ring. It makes a significant difference in power and has almost no affect on compression.

 

[jeremyc]

Thanks so much for the input!
I will try to scrape/sand the squish band and get the base gasket deleted. According to my research on these saws I should be fine with anything over 0.015 for squish... opinions?

@drf255 I don’t think I have the tools available to adjust the upper transfers unless you have some tips? Maybe a cutoff wheel on a pencil grinder?
76-78 seems like a lot of change for the intae floor?

Brad, for clarification you would cut the piston skirt after re shaping the port to achieve the desired timing ?
And you pretty much run a single ring in all sizes of saws or this one in particular? Just trying to learn what I can here...