ESE's works engine tuner

[husaberg]

I guess pulse jets bathe their reeds directly against the fire.

Pretty sure jet engines were the reason stainless and austenitic steels were invented like nimonic 80 as made famous for its nicker dropping properties on BSA Goldstar clubmans exhaust valves.

[ceci]

I guess pulse jets bathe their reeds directly against the fire.

Hi Flettner
On the left, the sheet at rest, allows an exit of burned gases through the pipe and blocks the outlet of the supercharging gases.
On the right the sheet is flexed due to the pressure of the supercharging gases.
The two previous drawings correspond to how the sheet have to behave in the mechanism, in a FEM study they do not behave like this, because there are different lengths (shorter in the center than at the ends)

[ken seeber]

UHV 2

Can see a couple of questions / points re this, but maybe if you could hold off for a couple more posts, it might become more clear and self-explanatory.

How to feed the reeds? Down thru holes in the head, maybe with an initial design something like this.




Cool, but how is the mixture going to get up there? Well, despite another alternative, I went for crankcase scavenging. So I blocked off the cylinder transfer ports and set in 2 aluminium tubes that were flush with the top deck of the cylinder





More to come..

[lohring]

The expanded gas at the exhaust port should be at a lower temperature than in the head. The temperatures would be even lower in the pictured setup. I bet steel reeds could work. My question is; would that be better than a straight FOS cylinder with a tuned pipe? Maybe at part power and low rpm, but I bet it would reduce peak power. If you're thinking about a supercharged engine, it would help. However, tuned pipes work really well on small engines.

Lohring Miller

[Tim Ey]

Anyone seen or plotted the ignition curve for a late model KTM125.

I have strobed and reverse engineered a
125SX 2017

RPM \ Spark timing (°CA bTDC) \ ExhaustValve Opening (%)

5000 \ 15
5500 \ 17
6000 \ 18
6500 \ 19
6800 \ 19 \ 0
7000 \ 19
7500 \ 19
7600 \ 18,8
8000 \ 18
8500 \ 17 \ 50
9000 \ 16
9300 \ 16
9500 \ 16
10000 \ 15 \ 100
10500 \ 14
11000 \ 13
11500 \ 10
12000 \ 8,5
12500 \ 6
13000 \ 20


I ported a little, tested a few pipes and got to 40HP at the backwheel in combination with an ignitech. 1500rpm powerband were also on the menue.

Looking from today, an 3° offset key or rotating the pickup a few degrees might hav been the KISS Version of that Ignitech installation.

[wobbly]

Wow , a total surprise there with the ignition timing.No advance at all in the mid range compared to what we think is " normal".
Thank you so much.

[ken seeber]

UHV 3

One obvious question is what could it offer? Given the somewhat (the combined hole size area and escape curtain area) limited port area it might not be high performance thing. For me the thinking is that if one could arrange the total fuel/air charge to come down from the head as a compact, tangentially rotating, increasing in size, “pancake” type slug, then maybe it might not escape out the exhaust, as is the Achilles heel of current engines. A sort of uniflow. If successful, this could then offer an improved fuel consumption and significantly lowered unburnt HC emissions. So, lower power and clean might see its application in say generation sets and other stationary units.

Could be total bullshit as well, but for me it was worth a go.

In all this and other ideas, we are competing with the time proven Schnurle scavenging principle and also the proven Husqvarna X-Torq scavenging system (a neat approach to eliminate the short circuiting losses via the A ports).

Hope these pics help. The reed was wire cut from 0.2 mm stainless “spring steel”. To do this, multiple blanks were sandwiched between 2 * 3 mm alum plates. Look at the detail of one of the wasted centre pieces. A beautiful process, just so handy to have a friend that has access to one of these.
To create the head, I made a 3d printed pattern to sand cast the blanks. Then a touch (?) of time on the lathe and mill, manual. The barrel was dowelled to match the location holes in both the head and reed. All interfaces are metal to metal, no gaskets or O rings.



More to come.

[dutchpower]

I have strobed and reverse engineered a
125SX 2017

RPM \ Spark timing (°CA bTDC) \ ExhaustValve Opening (%)

5000 \ 15
5500 \ 17
6000 \ 18
6500 \ 19
6800 \ 19 \ 0
7000 \ 19
7500 \ 19
7600 \ 18,8
8000 \ 18
8500 \ 17 \ 50
9000 \ 16
9300 \ 16
9500 \ 16
10000 \ 15 \ 100
10500 \ 14
11000 \ 13
11500 \ 10
12000 \ 8,5
12500 \ 6
13000 \ 20


I ported a little, tested a few pipes and got to 40HP at the backwheel in combination with an ignitech. 1500rpm powerband were also on the menue.

Looking from today, an 3° offset key or rotating the pickup a few degrees might hav been the KISS Version of that Ignitech installation.

Tim what a difference !!!!!!!!

[speedpro]

I can see the incoming streams circulating around the outer circumference of the cylinder and possibly not scavenging the centre so well. If the reeds are in the squish area they may not even get all that hot. Very interesting though, and wide open for a plain bearing bottom end and pressure feed to the reeds from a supercharger.

[speedpro]

Maybe even a Ryger style bottom end to separate the plain bearing bottom end from the cylinder

[Pursang]

I can see the incoming streams circulating around the outer circumference of the cylinder and possibly not scavenging the centre so well. If the reeds are in the squish area they may not even get all that hot. Very interesting though, and wide open for a plain bearing bottom end and pressure feed to the reeds from a supercharger.

Some of the Initial flow would be sideways, away from the wall and towards the centre.
One or more of the ports could be angled, to help scavenge the combustion chamber, but the curve of the reed might do that anyway..

Definitely cool, putting them in the in the squish, even more so in the Mk2, water-cooled head, big port version.

cheers, Daryl.

[Tim Ey]

Wow , a total surprise there with the ignition timing.No advance at all in the mid range compared to what we think is " normal".
Thank you so much.

Oh yes! That bugger totaly woke up with an ignitech. My guess was, that KTM wanted to ensure that this bike may also be used with russian potatoe booze...
Just short: Droppin' in "usual" advance of odd 29° in the low end, did not gain much.
That was, what I ended with a slightly modified ignition curve 8R of my Overrev CDI.
3 000 23
4 000 26
7 000 26
8 500 24
11 700 16
12 500 10
13 000 5
14 800 3
15 400 2
Here is a excelsheet to play with Here is the excelsheet of the different curves to play with

Tim what a difference !!!!!!!!

Indeed! Did you got an SXS CDI by chance? Or did I one of us mess it up badly?

[dutchpower]

What HP you start whit Tim (std .bike )


SXS till 2008

[wobbly]

The particular race KTM I am modelling made peak power at 11500 , so simply adding 5* of static advance would give the " usuall " 15* at this rpm.

[jonny quest]

What did you guys do with porting on the SX125?