ESE's works engine tuner

[Niels Abildgaard]

Some pictures

First is a conventional crankshaft for those who belive that a common crankvolume is OK.
For those who do not have true faith, I offer a compact mid bearing/seal solution shown in next two.


https://imgur.com/fk2c5Kh
https://imgur.com/qERR8Ec
https://imgur.com/kLlORzK

[Nath88]

I think have confirmed some ARC/HCCI operation of the injected YZ. I have a lean island on the fuel map, 15.5:1 AFR, centred around 8% throttle between 3300-5300rpm, in this area combustion goes from sporadic to very smooth and quiet, bike gains a little torque (accelerates a little), and the kill switch stops working. I can hold the kill switch as long as I like provided I don't move the throttle into the richer area. It doesn't 'feel' good though, the response is not linear when transitioning through the lean area, it feels like the engine is trying to run away. The throttle response is also pretty dull when it's running so lean.

[Flettner]

Niels, we are building a V twin using two of my cylinders but cylinder patterns modified somewhat. Its a rotary valve twin with variable housing/throttle technology, mark two TPI.
I'm building the crank with a center section having one bearing and a labyrinth seal. Connected via I believe what is called a Hirth coupling, I didn't know there was a name for this system, I just build a I see fit. This engine has been designed with a balance shaft of sorts. The big end pins are at 360 degrees but by making different crank centers can be what ever we want.

Cylinders are 350cc each.

[peewee]

Riding in sand requires a broad powerband and a close-ratio gearbox because the rpm-drops during upshifts are far greater than you would expect from just looking at the gear ratios.
With a spinning rear wheel your crankshaft may be doing 8000 rpm but your riding speed may only correspond to 4000 rpm.
During an upshift the spinning stops and after the upshift your crankshaft rpm wil have dropped well below 4000 rpm, where no-one is home, power-wise.
MX-practice is to grab the clutch and send enough torque to the rear wheel to get it spinning again. MX-sidecars with 800cc two-stroke singles are the worst:
some riders cover the whole track in third gear.

your right frits. to have any chance at success in sand racing, a close ratio gearbox is required and I would even like to try a super close ratio gear set as it may work better still. lets not forget the huge value of seemless up shifts as well. quick loss of speed and the massive rpm drops (where no one is home) could be all but avoided. its a shame such a gearbox would probly cost 4x more than my whole bike is even worth . hey that reminds me, since the hot topic now days is emmisions and fuel consumption, wouldn't a seemless gearbox help somewhat in those categories ? it must have crossed ktm's mind a few times I would think. unless the engineering and manufacturing costs are far to high for a simple dirt/enduro bike

oh ya heres the ratios of my latest sand hill racer. incase your wondering, the exh opens at a measly 84* atdc . three useable gears out of a total of five aint bad i suppose

15:33
16:24
18:21
20:19
27:21

[Grumph]

Niels, we are building a V twin using two of my cylinders but cylinder patterns modified somewhat. Its a rotary valve twin with variable housing/throttle technology, mark two TPI.
I'm building the crank with a center section having one bearing and a labyrinth seal. Connected via I believe what is called a Hirth coupling, I didn't know there was a name for this system, I just build a I see fit. This engine has been designed with a balance shaft of sorts. The big end pins are at 360 degrees but by making different crank centers can be what ever we want.

Cylinders are 350cc each.

Radial serrations and clamped up via a bolt through the center ? How'd you cut the radial teeth ?
Historically Hirth couplings have only been used where someone was prepared to pay a big bill....

[Niels Abildgaard]

Niels, we are building a V twin using two of my cylinders but cylinder patterns modified somewhat. Its a rotary valve twin with variable housing/throttle technology, mark two TPI.
I'm building the crank with a center section having one bearing and a labyrinth seal. Connected via I believe what is called a Hirth coupling, I didn't know there was a name for this system, I just build a I see fit. This engine has been designed with a balance shaft of sorts. The big end pins are at 360 degrees but by making different crank centers can be what ever we want.

Cylinders are 350cc each.

A picture of an Adler crank with Hirth coupling in center

http://www.motohistory.net/images/Twostroke14a.jpg

My proposal can maybe make a narrower enggine

[husaberg]

A picture of an Adler crank with Hirth coupling in center

http://www.motohistory.net/images/Twostroke14a.jpg

My proposal can maybe make a narrower enggine

This may interest you Niels

https://www.kiwibiker.co.nz/forums/a...p?albumid=4834

And this one
https://www.kiwibiker.co.nz/forums/a...p?albumid=4835

Plus as Frits mentioned the JBB
https://www.kiwibiker.co.nz/forums/a...p?albumid=4836
the Swissauto v4 was a hirth coupling.

There is a process that is used that fractures shafts used in production engines i am not sure how it differs or how it is done.

[Flettner]

Radial serrations and clamped up via a bolt through the center ? How'd you cut the radial teeth ?
Historically Hirth couplings have only been used where someone was prepared to pay a big bill....

Not that bad to build, I just used a tapered cutter in 4140 and some bearing blue. Machined the diameters oversize then once all fitted up, finish machine. I use a larger dia bearing in the middle so as to have plenty of contact area.
When finished I get everything nitrided.

Niels, I want a very ridgid crank, only one rod per set of crank webs and I want two separate crank cases. Weight is important but it must be robust enough to handle a hiding first.

[TZ350]

I think have confirmed some ARC/HCCI operation of the injected YZ. I have a lean island on the fuel map, 15.5:1 AFR, centred around 8% throttle between 3300-5300rpm, in this area combustion goes from sporadic to very smooth and quiet, bike gains a little torque (accelerates a little), and the kill switch stops working. I can hold the kill switch as long as I like provided I don't move the throttle into the richer area.

HCCI that is very interesting.

I got a "new to me" twin channel oscilloscope off Trademe today, the old one had died on one channel. So now I can see what is going on I am looking forward to having some time to get back to exploring the EFI 2T swapping maps issue.

[SwePatrick]

Reedpetals.. Has there been any more development to them?

I read somewhere on the web that someone has experimented with tapered petals.
Thinner at the end, and thicker at the base.
Say 0.5mm thick under the screws, and 0.3mm thick at the other end.
This to get high tension but low inertia.

Rgds
Patrick

[Frits Overmars]

Are there any classes for racing where a twincylinder two stroke is wellcome?

Superkarts.

First is a conventional crankshaft for those who belive that a common crankvolume is OK.
For those who do not have true faith, I offer a compact mid bearing/seal solution shown in next two.

I'm afraid faith and physics do not have much in common, Niels. In my experience engines are not very religious, but they obey unquestioningly to the laws of physics.

[WilDun]

Radial serrations and clamped up via a bolt through the center ? How'd you cut the radial teeth ?
Historically Hirth couplings have only been used where someone was prepared to pay a big bill....

Ariel decided to do a "cheapie" version of that centre coupling on their two stroke twins (ask TZ) and made theirs with a tapered shaft and woodruff key, as in ignition flywheels - It wreaked havoc with the ignition timing when it decided to move!
Don't think the Hirth arrangement would move (so long as the bolt remained tight).
Guess the "key" to machining the Hirth Coupling is as Flettner says, ie turning it to size and of course true, (after fitting up).

BTW does anyone know how the centre disc/common pin arrangement discussed before affects the flow into the transfer passages in a "V" engine?

[dtenney]

Superkarts.

I'm afraid faith and physics do not have much in common, Niels. In my experience engines are not very religious, but they obey unquestioningly to the laws of physics.

For Niels.......In addition to superkarts...check out outboard hydroplane race motors at www.grmracing.com. Plenty of 1, 2, 3 and 4 cylinder motors to look at.

[Frits Overmars]

does anyone know how the centre disc/common pin arrangement discussed before affects the flow into the transfer passages in a "V" engine?

It shouldn't. Seen from the inside of the crankcase the left and right flywheels appear identical. You can't see from there if one flywheel is much narrower than the other.

[Flettner]

Anyone here know about Mikuni oil pumps, can the drive shaft run either way? I see inside they are just a worm drive and an adjustable cam. I think I remember the valves are just spring loaded balls. It's not a rotating drum with ports is it or something like that? I don't want to pull this unit I have here apart if I can help it. It's out of a KE 175, reed version. By chance someone may know.
I guess I could just test in in the lathe.