The Bucket Foundry

**Flettner** · 26th October 2015, 15:43

Beads with hot glue

**husaberg** · 26th October 2015, 15:45

Originally Posted by Flettner

Beads with hot glue

Wee gem there Neil.

**WilDun** · 26th October 2015, 16:41

Originally Posted by husaberg

Wee gem there Neil.

What are you really thinking Husa?

Quite imaginative colour scheme I reckon!

Neill,
I was going to try and make something just for practice but all the work involved would be wasted so I'll try and design a relatively simple experimental engine which is actually going to work so i can follow your lead in doing this sort of stuff, it will be dull and unimaginative of course, but a means to an end - I'll leave the more imaginative artistic stuff to Husa!

I was thinking that you could use the same gear cluster contained in a "cartridge" with a corresponding cavity in whatever engine you were experimenting with, (giving you a "one box does all" type scenario). Royal Enfield did that with their GT250 ?

My cousin got driven off the road by a truck the other day (he was driving a tractor) and is likely to end up a quadriplegic, - you need to enjoy every day doing what you would like to do, (as opposed to what others think you should do for enjoyment), cos you just never know!

This casting lark will do me just fine I think.

**Flettner** · 26th October 2015, 18:09

Originally Posted by husaberg

Wee gem there Neil.

Ha Ha, I wondered who would spot that, should have known

Anyway see the beads are on a string, much easyer and faster to apply.
And we are all happy with the number of exhaust ports?

**Lightbulb** · 26th October 2015, 19:28

No wonder those patterns are so expensive. Pearls are not cheap. Maybe that is why he has Pearls of wisdom.
More tricks revealed, well done Flettner.

**WilDun** · 26th October 2015, 20:35

Originally Posted by Flettner

And we are all happy with the number of exhaust ports?

Yes of course (3?), but speaking for myself I think I'll just wait and see how it all pans out before commenting on the number. - reminds me on a couple of model aircraft engines I had (ie before they went over to the Schneurle system of scavenging) but I suspect this one isn't quite as simple!

**Lightbulb** · 26th October 2015, 20:40

Yeah this is really neat to see in person. Nice to see it taking place.
Neil

**Frits Overmars** · 26th October 2015, 21:51

Originally Posted by Flettner

And we are all happy with the number of exhaust ports?

You won't have to worry about getting sufficient blowdown angle.area and even less about cooling any exhaust bridges. But I wonder where you are going to put the pipes on the bike. Fortunately you're building a single and not a V-8

.

**Flettner** · 26th October 2015, 23:20

Originally Posted by Frits Overmars

You won't have to worry about getting sufficient blowdown angle.area and even less about cooling any exhaust bridges. But I wonder where you are going to put the pipes on the bike. Fortunately you're building a single and not a V-8

.

Yes, let me worry about the pipes, three into one tail section (with a trick inside). This cylinder has more to it than you can see yet, I don't have to worry about casting a water jacket as this cylinder will have more of a water bath

And don't let the head be attached to the cylinder

Athough it will have a ring ( probably two rings) and a piston (and they will touch but not touch the head).
This cylinder it destined to bolt onto the same bottom end as the sleeve engine just have a much tighter crank case (because of all the transfer port volume).
There is a second cylinder (same but different) that is designed to bolt on to the "High Pressure Crankcase" but uses a different induction system with the reeds being spread around the cank case transfers so as to use augmented flow, carbs connected to these reeds / transfers.
It's good to have a few cylinders on the go at once as while one is glueing you can be working on the other. Thats what I tell myself anyway.

**ken seeber** · 26th October 2015, 23:28

Originally Posted by Flettner

Yes, let me worry about the pipes, three into one tail section (with a trick inside). This cylinder has more to it than you can see yet, I don't have to worry about casting a water jacket as this cylinder will have more of a water bath

Fletto, how about having the three tailpipes all terminating together, but side by side. It'd just be interesting or vexing if they all blew different levels of smoke.

**Flettner** · 26th October 2015, 23:37

Originally Posted by ken seeber

Fletto, how about having the three tailpipes all terminating together, but side by side. It'd just be interesting or vexing if they all blew different levels of smoke.

You make the pipes and I'll run with that

They will be short as this should rev all to hell, I don't know perhaps 15000 / 15500 (100cc)

**Frits Overmars** · 27th October 2015, 03:39

Originally Posted by Flettner

You make the pipes and I'll run with that. They will be short as this should rev all to hell, I don't know perhaps 15000 / 15500 (100cc)

That's not hell; it's not even purgatory, just common practice. Lemme do some thinking on how to present this. I'll be back!

I'm back, with a couple of assumptions to keep things surveyable.
First assumption: bore and stroke are equal; it's a square engine. This means the stroke is proportional to the cubic root of the cylinder capacity.

The average piston speed is inversely proportional to the stroke.
The admissible rpm is proportional to the average piston speed.
so
The admissible rpm is proportional to 1 / (cubic root of the cylinder capacity)

Second assumption: maximum rpm is 14500 rpm for a regular 125 cc engine (based on the Aprilia RSA; may be a bit optimistic for any particular engine).
so
maximum rpm for your engine is cubic root (125 / cylinder capacity of your engine) x 14500 rpm

for a regular 100 cc engine that would yield a maximum rpm of 15620

But a FOS engine has 20% more angle.area for both the exhaust blowdown and the transfers, so your 100cc could rev to 1,2 x 15620 = 17182

Third assumption: rpm of maximum power is 0,9 x maximum rpm.

**Flettner** · 27th October 2015, 07:16

Originally Posted by Frits Overmars

That's not hell; it's not even purgatory, just common practice. Lemme do some thinking on how to present this. I'll be back!

I'm back, with a couple of assumptions to keep things surveyable.
First assumption: bore and stroke are equal; it's a square engine. This means the stroke is proportional to the cubic root of the cylinder capacity.

The average piston speed is inversely proportional to the stroke.
The admissible rpm is proportional to the average piston speed.
so
The admissible rpm is proportional to 1 / (cubic root of the cylinder capacity)

Second assumption: maximum rpm is 14500 rpm for a regular 125 cc engine (based on the Aprilia RSA; may be a bit optimistic for any particular engine).
so
maximum rpm for your engine is cubic root (125 / cylinder capacity of your engine) x 14500 rpm

for a regular 100 cc engine that would yield a maximum rpm of 15620

But a FOS engine has 20% more angle.area for both the exhaust blowdown and the transfers, so your 100cc could rev to 1,2 x 15620 = 17182

Third assumption: rpm of maximum power is 0,9 x maximum rpm.

Yeah but not but, I'm building it so I'm not expecting anything too special, in my world that is all to hell. If I saw over 15000 rpm I'd be doing back flips (I can now with this new hip)

The new hip is going to "get it" this week end, Acerbis four hour.