I'm casting another cylinder

I did a 50cc cylinder a decade ago:

http://team-nerdspeed.blogspot.com/2009/07/custom-cylinder-cast.html

And I've been working on a 75cc direct replacement for the Gilardoni cylinder, except more ports, bigger transfers and more aggressive port timing figures. I poured my first test on Sunday, which I thought was a total failure. I cracked the mold yesterday and it turns out it was a failure, but not by much. I'm going to make some changes to my burnout process and mold design and try again soon.

I mostly update my instagram @joshspaceman, but figured I should share here as well.

75cc Cylinder.jpg

Re: I'm casting another cylinder

Awesome! Please keep it picture heavy and up to date for non instas.

Re: I'm casting another cylinder

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

can't wait to see this rip

Re: I'm casting another cylinder

> Ryan Graeme Wrote:

> -------------------------------------------------------

> Awesome! Please keep it picture heavy and up to date for non instas.

That^ . Please .

Insta what ??? ;)

Re: I'm casting another cylinder

Jack Rutherford /

instagram users

Re: I'm casting another cylinder

> Jack Rutherford Wrote:

> -------------------------------------------------------

> instagram users

I know ... Just kidding . ;)

I don't use Instagram , like a lot of other sites I never visit .

Re: I'm casting another cylinder

Douglas Binder /

Looks pretty close to me. Will you plate it or use an iron sleeve? I tried plating mine but the plating failed so when I get back to that project, I'll just sleeve it and call it good.

Re: I'm casting another cylinder

Johnnie Distefano /

This is awesome!

Re: I'm casting another cylinder

Anonymous User /
scootertrash

Whuddup Josh, heck yeah I like those big fins.

Re: I'm casting another cylinder

That think will rip, and I'll be first in line. I have production conections in China. Holler at ya boi.

Re: I'm casting another cylinder

awesome!

cool to see this getting bumped

Re: I'm casting another cylinder

Thanks everybody. Doug - I'm going to have it / them professionally plated & honed. I know that nikasil is actually a somewhat simple process on paper, but I know there's finesse in getting it right. Same goes for honing, so I will be working with a Pro on those aspects when we get there.

Here's a bunch of pictures, but a note on process. I read everything, all the books, weirdo Kart / Snowmobile / Jetski / RC Forums , the undisputed 2-Stroke beast designer that is Jan Thiel & his lovely Aprilia RSA engine... and try to reverse engineer existing designs to see what actually works in reality. When In doubt, I crack open Two Stroke Performance Tuning 2nd Edition by A. Graham Bell for cheat sheets.

The first cylinder I made in Seattle was basically a one-shot only art project. Which was dumb, but now I know better. This current design was figured out with math and formulas and copycatting. I drew up a port map, designed the cylinder in 3D, then produced 3D prints of the model with mold registrations already built in. I made silicone RTV molds of the ports (insides) and the cylinder (outsides). The port internals are cast in a sand/plaster mix, assembled then plugged into the mold. The mold is closed up and filled with hot wax. Basically Lost wax process from here on out.

Port Map.jpg
Cylinder dimensions.jpg
Porting Image.jpg

Re: I'm casting another cylinder

more pics

Cylinder Model External 2.jpg
Cylinder Model External.jpg
3D Print and Gila.jpg

Re: I'm casting another cylinder

even more pics

3D print Port Structure.jpg
Port Internal Molds.jpg
Port Internals in plaster.jpg

Re: I'm casting another cylinder

yet more pics

Making Mold Early.jpg
Mold Halves with Core.jpg
Plaster Core in Mold.jpg

Re: I'm casting another cylinder

Re: I'm casting another cylinder

first cast test result

75cc Cylinder.jpg

Re: I'm casting another cylinder

Anonymous User /
scootertrash

A dab of JbWeld and run it! ;)

Re: I'm casting another cylinder

Have You thought about useing a Yamaha jog 100cc piston? They are 48mm!

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Douglas Binder /

You probably know this but getting the sprues as high as possible improves the fill and detail. Good luck. It's really great seeing someone else doing this. Alex and I had trouble with porosity (tiny holes on the cast that show themselves when you machine the bore). Please let us know if you solve that one. Because I plan to go with an iron sleeve, it doesn't matter to me but I would like to understand it. I won't get back to my cylinder till my airplane is done and that might take years!

Re: I'm casting another cylinder

> Douglas Binder Wrote:

> -------------------------------------------------------

> You probably know this but getting the sprues as high as possible

> improves the fill and detail. Good luck. It's really great seeing

> someone else doing this. Alex and I had trouble with porosity (tiny

> holes on the cast that show themselves when you machine the bore).

> Please let us know if you solve that one. Because I plan to go with an

> iron sleeve, it doesn't matter to me but I would like to understand it.

> I won't get back to my cylinder till my airplane is done and that might

> take years!

Are you talking about an airplane that u will be piloting? Plz say yes

Re: I'm casting another cylinder

>>>taykoff [s2m] /

Inspiring work. Even more impressed that you did this in Sketchup...look forward to seeing this rip!

Re: I'm casting another cylinder

Yo, you know they sell Gila kits on Treats right?

Kidding, badass work.

Re: I'm casting another cylinder

Douglas Binder /

Rocco, yes. Kitfox II.

Re: I'm casting another cylinder

All you people chiming in how you want one... a eurokit and a dio reed adaptor will have you ripping your god damn dong off.

Re: I'm casting another cylinder

For those playing at home, shrinkage is running about 2% in the thinner parts and 5% in the thicker sections. I may make some changes to the mold if improvements in the burnout process don't yield better accuracy.

Also here's a side by side look of the first test with a trashed Gilardoni I have laying around.

Gila Comparison.jpg

Re: I'm casting another cylinder

> Josh G Wrote:

> -------------------------------------------------------

> For those playing at home, shrinkage is running about 2% in the thinner

> parts and 5% in the thicker sections.

videotogif_2019.11.19_08.22.15.gif

Re: I'm casting another cylinder

wow it’s a lot of work .. time you get it right all 3 girls you ever dated will be on social security...

D2BF5B8E-19EA-4AAB-9D9A-E451576BA5A7.png

Re: I'm casting another cylinder

Overpriced Parts /

You are a true trooper/purpose but you’re wasting your time, By the time you think of it 100 people think of it when you think of anything it already has been done

Re: I'm casting another cylinder

This is crazy to me that people are saying it is a waste of time. It seems he is more into this for the process then an easy way to get an end result. I think it has been fun just watching him post his results.

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