Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

You need to put it in a metal flask, I use soup cans with the top/bottom cut off

Mine were all cracking before I started putting in a flask. Maybe a paint can?

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I notmaly used an oven barrel, but the cylinder didn't fit in there thats why I welded the sheet metal thing around it.

But next time its gonna be round.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Russell Huddy /

I’d also recommend using commercial investment powered instead of your plaster mixture. Mix according to instructions.

This should help it hold together better through burnout. Your also not burning out long enough or hot enough. PLA needs approx 1300f (730c)

This is really fun to watch, I really miss casting

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

The problem with the investment plaster is that I don't get in in germany it is almost impossible. There is basically no one that imports it and if there is one it is to expensive to get.

But if anyone got a suggestion where yo get it it would be appreciated!

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

I understand this problem well enough. Hit me up in a direct message. The problem is likely a combination of your investment as well as the burnout.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

I have not had good results from the commercial investment, waste of money.

I also run like 10% infill, I can't prove it but I think the pla expands a little before it melts and helps crack the plaster.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

> Josh G Wrote:

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

> I understand this problem well enough. Hit me up in a direct message.

> The problem is likely a combination of your investment as well as the

> burnout.

Also, discuss that shit here! That's what the forum is for, I'm working my way up to a cylinder but I'm getting close

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

10% infill seems like a good standpoint.

Thats what I am using to and it normally have me good gesults.

So next time a round flask

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Yeah the problem I'm having now is that the pla melts and soaks into the plaster. When the molten metal hits it, it outgasses and creates bubbles in the small features.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Ľ̷̝̽͒i̶̛̼͑͠ȁ̸̧̛̽m̵̻̟̯̀̅ ̷͎̙̽̊F̶̲̺͑̓ F /

Have you seen the wax filament yet? It’s a bit expensive but may be what you are looking for

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Ehhhh, I don't see any advantage to it, the pla almost burns out better than wax, you are printing it hollow so it's not like doing lost wax where there is a bunch of material to get rid of

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

Pla burns out quite well. But i have hade the problem withe the pla soaking into the plaster as well. The only work around I found was to burn it out longer.

I have seen the wax filament but I don't think that it would give me an advantage over the pla.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

I'm hoping better mold design cures it, I've been trying to pour them from the top but I flipped it now so it's bottom fill and much better vents.

I'm going to try this one more time then I'm buying a vacuum pump and doing vacuum cast.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I have been filling from the bottom to much better result in the end.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

You can dissolve PLA with certain industrial solvents. Anything containing Methylene Chloride or Tetra Hydro Furan would work:

http://www.vinland.com/blog/?p=68

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

Quite nice nice idea with the dissolving.

But I need to burn the mold either way

To fully dry it and covert the plaster.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Yeah I think I have things working pretty well with the burnout right now, it's a good idea but I don't want to add more chemicals into the mix and potential issues.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I have a new cylinder ready for burnout.

Hopefully I will get to cast it on this weekend

16075231399213387929761130659865.jpg

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Looks great!

Also I learned another lesson recently, can't let the mold cool down then heat it again. I had to pause burn out and leave for a few hours, came back and plugged the oven back in and when the plaster heated up again it crumbled.... Try again!

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Good Luck Kilian & take your time with the burnout!

I'm considering giving up on lost wax for my cylinder project & going to 100% cope & drag plaster assembly. ¯\_(ツ)_/¯

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Why such low timing?

50cc is very limited as far as torque even with decent aux ports and good transfers.

Are you going to run a high rpm pipe on it to get some big revs with low blowdown for a wider band? It’s just a curious way to go for a racer

I love the idea of a wide reaching power band ripper tho

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

The engine is going to be used in offroad moped racing were most of the winning cylinders are ported polini or athena i forgot zündapp cs25 cylinder which have only a single exaust port. But the ported cylinders often have quite the high exaustport timing. As there are a maximum of 3 gears allowed you need to have quite the wide powerband to have a chance of winning.

I am hoping to achieve that with a large blowdown time area but low timing. The exaust port is extremely wide and shaped for best flow (picture). And yes that limits power, but that isn't terribly important as most other racers have "only" 12hp and with that portlayout and exaustport I am hoping to at least get 14hp but with a exactly as wide or even wider powerband. The pipe is going to be in resonance at quite high rpms somewhere between 12.500 and 13.500 rpm. Also the exaust opening on which the exaust bolts on is an elliptical constriction which helps to keep blowdown velocity high which should also help. Than the constricted ellipse goes over to a normal circular opening.

16077169391867560136371932871902.jpg

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

And also I am not running good transfers I'm running the best transfers, which is an overstatement but they are really good (good controll over the angle of incoming gas because they only bend in one dimension and the layout has ben proven to be very good to (aprillia rsa) There are some duds getting 25hp+ out of that portlayout of corse with higher timing but you get the idea)

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

I didn’t know it was off-road or I forgot.

Should be great

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I have just casted the cylinder and its looking pretty good. I will open the mold in 20 minuts

16078606722755404480338177703869.jpg

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Is it 20 minutes yet?

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I have waited a bit longer to let it cool. But i will open it right now.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I have got it out partially and it looks quite nice its definitely usable i will need to use a lot of jb weld and some welding because on some faces there is a lot of inclusion but they are only on the surface so its not that big of a deal

16078666000102653736145314718556.jpg

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Looks great!

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Looks great! congratulations!

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