ESE's works engine tuner

[peewee]

i hope by the weekend ill be able to start on engmod. still i need to get to the local machinist and have the bore skimmed of all the excess weld so the piston can fit. assuming the rsw drawings are still up to date then i figure i could just make some templates of those transfer wall radiuses and use that somewhat as a guide ?

[Frits Overmars]

A bottle of Nitrous with a T, one line into the carb the other into Frits helmet.

Love you too, Wob. But like you, I prefer a single malt to a draught of N2O.

[husaberg]

Yes it's all gone a bit quiet. But lets recap, for charge to flow from the crank case to the cylinder at speeds that would normally stall the transfer charge (not enough blow down time) there must be a method of "super" charging the crank case (I don't suggest mechanical) crank case pressure must be increased before transfer takes place. How is this done? That is the key, suggestions anyone.

I also think it must pre-compress the inducted volume to a larger degree, which allows for more actual mass of flow to occur.
It might also allow for some direct flow into the cylinder driven by the inertia and speed of the inrushing pre compressed mixture.(think venture or ram jet)
I still muse it has a variable crankcase size

[Frits Overmars]

I still muse it has a variable crankcase size

With a crankshaft at one end and a reciprocating piston at the other, I dare you to mechanically connect the two without having a variable crankcase size. I don't see a way.

[husaberg]

With a crankshaft at one end and a reciprocating piston at the other, I dare you to mechanically connect the two without having a variable crankcase size. I don't see a way.

Yes very true I was meaning being able to vary the size beyond these actual parameters. Thus to be able vary the initial size according to the engine speed.

[m4r]

Yes it's all gone a bit quiet. But lets recap, for charge to flow from the crank case to the cylinder at speeds that would normally stall the transfer charge (not enough blow down time) there must be a method of "super" charging the crank case (I don't suggest mechanical) crank case pressure must be increased before transfer takes place. How is this done? That is the key, suggestions anyone.

It actually can't be the crank case, because it runs on fuel only, no oil mixed. The crank is probably lubricated by that dry sump oil can with the filter on top mounted at the side.

[Frits Overmars]

I was meaning being able to vary the size beyond these actual parameters. Thus to be able vary the initial size according to the engine speed.

That's possible.

Wobbly will no doubt recognize this patent drawing from his hero Helmut Fath. But compared to a conventional two-stroke I would not really call it simple.

[husaberg]

That's possible.

Wobbly will no doubt recognize this patent drawing from his hero Helmut Fath. But compared to a conventional two-stroke I would not really call it simple.

I was musing something less mechanical more pneumatic as a side note. More in the reed cavity area, more a bypass.
One of the guys that used to work with Helmet was Ferry Brouwer (not sure of the spelling) he allegedly used to remove so much of the rear skirt of the piston on the (I think TR2) that the inlet closing became simultaneous with the transfer opening, this was pre reed days of course. Not sure what would make of the inlet duration or the primary compression on piston ports.

[Frits Overmars]

One of the guys that used to work with Helmet was Ferry Brouwer (not sure of the spelling)

My old mate Ferry spells his name the same way you do, but I doubt if the late Helmut Fath would trade his first name for a headgear description.

Ferry allegedly used to remove so much of the rear skirt of the piston on the (I think TR2) that the inlet closing became simultaneous with the transfer opening, this was pre reed days of course. Not sure what would make of the inlet duration or the primary compression on piston ports.

Ferry and I did a lot of silly things. With about 134° transfer timing his piston shortening would give an inlet timing of 226°.
It was not uncommon in those days; Bultaco did it too on their TSS250. Remember: back then the carburettors were tiny by current standards.
A more drastic mod by Ferry was raising the inlet ports until they opened at BDC. That's right: C-transfer ports directly connected to the carbs; no reed interference (but quite a lot of Read interference; dear Phil MBE was not the easiest person to get along with).

[seattle smitty]

Just catching up here; FWIW, the new, supposedly eco-friendly brake cleaner (comes in a green can, naturally), is acetone: highly flammable, but no chlorine and evaporates fast. Traditional brake cleaner (which is much better for brake work IMHO) still comes in, usually, red cans. Appreciate that link, Frits; hope the poor guy has fully recovered.

Also, somebody commented on my metric system rant quoting my crack about Euro-socialist-yakkety-yak. Hope it was understood that the rant came from occasional minor irritation at mixed measuring systems, and that the crack was made in jest. To be serious, I rather admire the French in particular, as contrarians by nature, and I wish our recent idiot leader from Texas had taken French advice instead of getting us into a two-front war, creating new terrorists by the thousands (and now ISIS) and putting this country deeply in debt to the Chinese . . . (end serious rant).

Foundry story from decades ago: Paid a visit to a tech school where I had taken a couple of quarters of basic machining classes. The instructor said, "Come take a look, we're just getting ready to start a metal casting section and we did a test-pour last night." We went into a side room with some shiny new gear and he handed me a chunk of aluminum. I couldn't even tell what they had been trying to make; the metal was utterly shredded and distorted. I handed it back and went over and picked up a handful of the casting sand. With no experience one might have considered the sand to be dry, but by foundry standards it was soggy! "Steam," I said. This was a classic case of how if you know a very little when the others know even less, you can appear to be a real tech-whiz and cover yourself in glory.

[AndreasL]

A more drastic mod by Ferry was raising the inlet ports until they opened at BDC. That's right: C-transfer ports directly connected to the carbs; no reed interference (but quite a lot of Read interference; dear Phil MBE was not the easiest person to get along with).

I have tried to get my head around what happens when having a C-transfer in a non reed engine but cant get any further then its not good...
Or does it have some kind of benefit at all?

[AndreasL]

Talking about brazing cast iron cyliders.

What do you think is the best method and rod for the job?

A welder I have spoken to was thinking about "TIG brazing" with https://www.castolin.com/product/castotig-45703-w

Pros and cons are welcomend.

[husaberg]

My old mate Ferry spells his name the same way you do, but I doubt if the late Helmut Fath would trade his first name for a headgear description.

Ferry and I did a lot of silly things. With about 134° transfer timing his piston shortening would give an inlet timing of 226°.
It was not uncommon in those days; Bultaco did it too on their TSS250. Remember: back then the carburettors were tiny by current standards.
A more drastic mod by Ferry was raising the inlet ports until they opened at BDC. That's right: C-transfer ports directly connected to the carbs; no reed interference (but quite a lot of Read interference; dear Phil MBE was not the easiest person to get along with).

Bill Ivy wasn't a fan of Phil.I guess that was mutual though.
I was musing the inlet would have been more degrees with such drastically shorterned skirts.
So according to your last post the conventional reed inlet was not opening until?

The flow velocity from the crankcase to the cylinder will increase as long as the crankcase pressure is higher than the cylinder pressure.
At max.torque rpm the flow velocity reaches its maximum at roughly 10° to 20° after BDC; then the crankcase pressure and the cylinder pressure are equal, and they are also roughly equal to atmospheric pressure. The reed will only start to open when the crankcase pressure drops below atmospheric pressure, so it won't even begin to open until after BDC.

[Grumph]

Talking about brazing cast iron cyliders.

What do you think is the best method and rod for the job?

A welder I have spoken to was thinking about "TIG brazing" with https://www.castolin.com/product/castotig-45703-w

Pros and cons are welcomend.

I've not used that method personally but I'd guess that better control of just where you're heating and a cleaner working area would make it better overall.
Better than oxy acetylene at least...

[Yow Ling]

Frits, on the Ryger facebook they write this
"and yes ! we do have 70 bhp and 30k rpm and 80% less emissions....it is the result of 10 years of development and a lot of hard work.
BUT ! it is NOT about rpm or horsepower it is about a clean twostroke engine with superb characteristics !"

Are you able to confirm these are all from the same engine or from several different engines