Hacking a 046 together, I have questions, can y'all help?

[Stump Shot]

Cool, thank you.

The meteor piston will be here tomorrow and I can start working on this thing. I measured the squish with the stock piston and no gasket, it didn't squish the .025 lead wire I use. So, should I cut the squish band unit I have a certain amount of surface area? like a ratio that relates to the area of the bore? and then cut the base until I have the squish correct?

And this is assuming the new piston measures like the replacement. I will measure the new one first

I would recommend you do your figuring from the piston that you are going to use. Even a new OEM one could be slightly different, not often so, but it happens.

 

[drf256]

I would recommend you do your figuring from the piston that you are going to use. Even a new OEM one could be slightly different, not often so, but it happens.

Yup, good advice.

I had an odd oem 046 piston that was .008 shorter than any other 046 piston in my shop.

Meteor 046 slugs have wider skirts than oem. Around 4 grams heavier without and 6 grams heavier with the meteor pin.

You’ll have to trim the oem pin if you want to use it. It’s too long. Easy peasy on the lathe.

 

[Deets066]

I had an 066 piston that was .017 shorter in crown height.

 

[Stump Shot]

Yup, good advice.

I had an odd oem 046 piston that was .008 shorter than any other 046 piston in my shop.

Meteor 046 slugs have wider skirts than oem. Around 4 grams heavier without and 6 grams heavier with the meteor pin.

You’ll have to trim the oem pin if you want to use it. It’s too long. Easy peasy on the lathe.

If I remember correctly, the skirt changed the intake timing a tad as well.

 

[Stump Shot]

I had an 066 piston that was .017 shorter in crown height.

Had an 036 that was way different.

 

[Wisconsin Welder]

.022" with the new piston, no gasket. gonna make a degree wheel at some point today and take timing numbers, have never done that, I'm having fun.

 

[Wisconsin Welder]

Finally got time to make a degree wheel, this is with the new piston, no gasket........

Squish is .022"

Exhaust 104
Transfer opens at 118
Intake 73

The roofs of the transfer ports aren't parallel to the uh, anything, the intake side of the transfers opens, then 7 degrees later the exhaust side is showing. I don't know what I am looking at exactly here. I still want to cut the squish band for a compression bump, but it seems like the numbers are ok, and Im gonna lose that if I have to cut the base to get squish back after doing that.

 

[Wisconsin Welder]

Also, the skirt is clear of the intake opening 18* BTDC, would raising the intake gain anything? assuming it doesn't cause ring problems?

 

[drf256]

Finally got time to make a degree wheel, this is with the new piston, no gasket........

Squish is .022"

Exhaust 104
Transfer opens at 118
Intake 73

The roofs of the transfer ports aren't parallel to the uh, anything, the intake side of the transfers opens, then 7 degrees later the exhaust side is showing. I don't know what I am looking at exactly here. I still want to cut the squish band for a compression bump, but it seems like the numbers are ok, and Im gonna lose that if I have to cut the base to get squish back after doing that.

How did you get these numbers?

Only asking because there can be a tremendous variation in the numbers depending on how you’ve arrived at them.

The only true way is with a ring and a pick IMHO. After visually guestimating, I toss a ring in there and see where I’m actually at. I’ve been off with visual degree of trannys and ex by 10* at times.

If you truly have a 14* Blowdown jug, it should run very very well as is. Should have a D chamber as well.

Also, the skirt is clear of the intake opening 18* BTDC, would raising the intake gain anything? assuming it doesn't cause ring problems?

Never tried it. As long as you can keep the bottom ring pin tucked at BDC, you could raise the roof. On most Stihl’s, the ring gap was always too close for me to try. I usually keep the PTO roof corner rounded to keep the lower pin tucked, at least more rounded than the Fly side.

 

[backhoelover]

I had an 066 piston that was .017 shorter in crown height.

If I remember correctly, the skirt changed the intake timing a tad as well.

What kind of lathes do y’all have. Looking for one that’s good and on cheap side to mess around and try to learn something.

 

[Stump Shot]

What kind of lathes do y’all have. Looking for one that’s good and on cheap side to mess around and try to learn something.

Old 9" South Bend

 

[Wisconsin Welder]

How did you get these numbers?

Those numbers are from when the plane of the piston uncovers the port, not the bevel around it, not when I could see light with a flashlight etc. I used shim stock and four letter words, each port had about five numbers I wrote down and when I felt I was consistent enough thats where I ended up.

It is a D jug, and numbers-wise I am still just standing on shoulders here, but as far as the shape of the ports, the bevels around them and their size, this cylinder seems very nice already.

With that 18* on the intake port, I should probably just leave that roof alone, not much travel in
that 36* total rotation there, this is just a guess

What kind of lathes do y’all have. Looking for one that’s good and on cheap side to mess around and try to learn something.

Any machine work I do is at work.

 

[Wisconsin Welder]

Old 9" South Bend

Farmer down the road has one of those that hasn't been touched in forever, won't sell it, I'd love to find one of those. He said it runs on 110v, is that pretty common?

 

[Stump Shot]

Farmer down the road has one of those that hasn't been touched in forever, won't sell it, I'd love to find one of those. He said it runs on 110v, is that pretty common?

Yes, I believe so, they were built for a lot of years and last just about forever. There's lots out there to buy to refresh them as well.

 

[drf256]

What kind of lathes do y’all have. Looking for one that’s good and on cheap side to mess around and try to learn something.

I’ve got an OTMT rebranded Chinese lathe. It’s the same 8 x 16 minilathe that is made by multiple manufacturers. It’s got autofeed in both directions and serves its purpose for me. Some jugs are tough to cut on it.

The grizzly is a good lathe for the money.

And southbend is what I’d love if I had the space.

 

[Wisconsin Welder]

Cut the squish band with my home made B.S. thing and it worked ok, don't like the variation in measurements from the band to the base, I took about .015" out, but the aforementioned measurement varies by almost .010" in one spot :|

It was also a pain to get the corner between the band and cylinder wall to clean up, the first try at it, the cutter wasn't getting all the way out to the wall and there was a step.

 

[Wisconsin Welder]

Thanks to all the info I have found here and questions answered, I finally got time to get this together, I ended up cutting .025" off the base and re-cut the squish to .020". Ended up with 195 psi.

Cleaned flash out of transfers etc. widened the intake a little bit, made the exhaust huge lol. Shaved about .015" off the flywheel key and engraved the words
"This was stolen from my name and number" under the muffler. Put on a super sexy Tsumura bar Julian sold me and called 'er good.

This thing fricken screams, it makes my stock 462 feel like a toy. Tomorrow if I can find time I want to run the two head to head.

Thanks a lot guys, no *s-word, really cool of y'all to put all this info up here. I've bought that 2-stroke book and am learning more, hopefully I can figure some *s-word out one day and share that.

Next up is the very clean 066 I picked up a while back, this one is gonna take some time.