ESE's works engine tuner

[andreas]

Re the cooling of the spigot.
As we already know that wrapping a header will instantly cause deto from overheating the slug, then the heat uptake in that area for sure
has enough time to wreak havoc.
So by inference a cool duct would also have time to cause a positive effect.
But I well know assumptions are errors waiting to be revealed, so hard evidence is needed.
I just happen to have that, as I have been drilling holes and cutting slots into the flange faces of KZ2 castings the results are easily seen and repeatable.
On track the simple mod reduced the egt by around 30*C - a jet size spot on.
So now we run 1 jet leaner over the original dyno baseline weather corrected RAD, and can run all day at 640C with no deto.
Absolutely impossible previously.
The bulk cylinder water temp is the same as before at 45*C exit, but on the dyno it is now possible to touch the flange bolted to the cylinder,after a hard all
gear run up.
Previously it was way too hot to do this.
At the time I didnt recognise that I could have leaned it down on the dyno - and make more power, but on track the data log was immediately conclusive.

I am sceptical about cooling the header with heat radiating plate fins or whatever, as this would be detracting from the pipe heat energy available - BUT, it may be a workable
compromise if the duct cannot be kept cool enough - for whatever reason.

Maybe a thermal barrier, like a gasket where possible, to the spigot/header? A volume/port size reducing contraption bolted to the floor will do more harm than good , because of it's insulating effect?

[pete376403]

I have it saved somewhere ........

Thanks for posting that. I used to subscribe to Cycle, from about 1969. Sometime ago, in a fit of madness I traded all the boxes of back copies for some space in the attic, save for the very last issue they published.

Reading that bought back memories of all the things I wanted to do to my F9, but ignorance, life, etc., got in the way.

Good luck with your search for an f5/f9 - or, if you are determined for it to be a 250, find an F8 Bison

[husaberg]

Thanks for posting that. I used to subscribe to Cycle, from about 1969. Sometime ago, in a fit of madness I traded all the boxes of back copies for some space in the attic, save for the very last issue they published.

Reading that bought back memories of all the things I wanted to do to my F9, but ignorance, life, etc., got in the way.

Good luck with your search for an f5/f9 - or, if you are determined for it to be a 250, find an F8 Bison

Two Stroke Fridge

Flet i think made a mold for the heads already.
I think i remember from somewhere the gearbox is the same as some other Kawasaki.
So he really only needs a bottom end as i are assuming hes making a cylinder.
Flet even has a period Lake injector he made

[Flettner]

F9 stuff, reporting for duty TZ.😆

[breezy]

hope its good game

[F5 Dave]

Please. Not here. Team sports are for school kids.

[Frits Overmars]

Frits, don't know if I have to congratulate you or ask you, looking at this graph:
is from my excel, entered all the RSA data (cylinder and head, and then calculated your FOS pipe.
Red is standard FOS as by your fomulas with 57.5 BHP at crank and a speed of sound of 587 m/s to get the same length as the tubo102.
Green is a copy as good as I could get it within the limitations of my sheet (max half a milimeter here and there, and without the last baffle) with a Wobbly-duct at the front.
So: did you derive your FOS from the RSA pipe ? If, so, you did an excellent job
Or is it an everlasting fine-tuning of your exhaust concept from the seventies, and than it is a outstanding-out-of-this-world job

Thanks for the flowers Jan .
The development of my pipe concept has been a continuous process, from the seventies, as you noticed, until now.
I tried to understand what happens in an exhaust pipe and I tried to develop a theoretical pipe shape that would promote the desired physical events. This resulted in equations that gave fairly good shapes, which however were quite complicated to produce in sheet metal.
Next, I tried to distinguish between fundamental details and details that, though theoretically correct, had little influence on the end result, which allowed me to simplify the pipe concept into what it is today.
Most of the recent work went into making the concept universally applicable, from a 2cc model engine to a 700cc MX single.

Of course there have been interactions between the physical theories and the measured results, like you did, when you juggled the speed of sound in order to match the pipe length to your chosen RSA example. Incidentally, that is exactly the recommended way of using the concept.

[KKT]

I apologize if this is the wrong place to ask, i have been a member on here for quite some time and have been working my way through this thread, but this is only my second post.

I love twostrokes, and i am in many ways stuck in the late 70's - 1980, i'm old enough (51) to remember watching the 50cc and 80cc GP races on TV and they still amaze me.

The 50cc bikes are coming back strong in the Freetech class, and in classic 50 racing, but otherwise they seem like a forgotten era, many bikes are retired to museums and private collections.

I've spent many hours looking for more info, especially about the Garelli 50gp from the last years they raced ( I believe they all had Jan Thiel's engine design) Kreidlers, Minarellis, Derbi 50 and so on, google does come up with nice photos of the bikes, but that's about it. It looks like it's a deep secret of how the cylinders looks like inside, what the portmap looks like, and all the technicall stuff like disc valve timing, port sizes and durations i would love to see and read about and learn what made them so incredible fast.

Can anyone help directing me to where to look ?

Thank you.

[JanBros]

Thanks for the flowers Jan .

Frits, but can you share some of the flowers with Wobbly ?

perhaps I should have expalined it more : not only is FOS very very close, also Wobbly's exhaust duct is spot on with it's length and starting diameter of the pipe !

just wanted to show this graph to everyone, that with some simple calculations like Wobbly's duct and your FOS pipe, how close you can get to a factory pipe when you have enough correct data

[TZ350]

F9 stuff, reporting for duty TZ.��

I am off to see Flettner today for a frame and engine. He is about an hour and a half's drive away, so pretty handy.

I would still like another spare Kawasaki Bighorne or Bison engine and I am not kidding, I can pick it up easily from anywhere especially the USA.

I once won five good Suzuki T500 engines and spares on Ebay. A half tones worth and the price was reasonable. They were picked up and shipped out of Ohio no problem. They are now doing duty in three Senior post classic racers. Not ours, after a bit of thought. Chambers and I sensibly decided that we did not need to ride bikes that frighteningly fast so we passed the engines on at cost. Junior post classic looks more our level. If anyone in the US has a Kawasaki 350/250 F9, F8 or F5 engine or two they might sell I would be very interested.

[wobbly]

I too must thank Jan for the flowers , but as I have just reread some posts I must apologize to Andreas if i gave incorrect info about the Motoplat - its been 30 years
is my excuse.

[adegnes]

Mockup of my new engine in the frame.
Green is small carb with reed intake, blue is big 24/7 intake with a slide valve for opening at WOT.
The case is pretty much ready for machining.



Constant rpm/load/throttle opening(WOT, no throttle)

Questions:
- Anything wrong with mounting injectors where I've marked in the drawing?

- Been thinking I should use two and have one open as the other closes to minimize "gaps" in delivery - necessary? One would be preferable, less parts.

- Injector size? (19k rpm, 70/30 methanol/nitro by weight, 30ish hp}
Here's my crude calculation

(50cc x air mass 0.00129gcm3) x 20000rpm = 1290g Air
1290g / 3:1AFR = 430g fuel

(0.7 x methanol 0.792gcm3) + (0.3 x nitromethane 1.14gcm3) = 0.896gcm3

430 / 0.896 = 480cc

480 / 0.8 duty cycle = 600cc

600 x 50% safety factor = 900cc

Does one 900cc/two 450cc injectors sound sensible? (two 900cc if I want them to alternate on/off)


Picture of Moped Dick Experimental Test Vehicle #1 in front of what should have been salt flats.

[Frits Overmars]

I love twostrokes, and i am in many ways stuck in the late 70's - 1980, i'm old enough (51) to remember watching the 50cc and 80cc GP races on TV and they still amaze me.
The 50cc bikes are coming back strong in the Freetech class, and in classic 50 racing, but otherwise they seem like a forgotten era, many bikes are retired to museums and private collections.
I've spent many hours looking for more info, especially about the Garelli 50gp from the last years they raced ( I believe they all had Jan Thiel's engine design) Kreidlers, Minarellis, Derbi 50 and so on, google does come up with nice photos of the bikes, but that's about it. It looks like it's a deep secret of how the cylinders looks like inside, what the portmap looks like, and all the technicall stuff like disc valve timing, port sizes and durations i would love to see and read about and learn what made them so incredible fast. Can anyone help directing me to where to look ?

Sure we can, KKT. Take a look here: https://drive.google.com/drive/folders/18l2ShH-MzrnTO0uEk9rNTk89_KgwgWof

Frits, but can you share some of the flowers with Wobbly ?
perhaps I should have expalined it more : not only is FOS very very close, also Wobbly's exhaust duct is spot on with it's length and starting diameter of the pipe !
just wanted to show this graph to everyone, that with some simple calculations like Wobbly's duct and your FOS pipe, how close you can get to a factory pipe when you have enough correct data

I'll be glad to share, Jan. You may have noticed that my method of starting at the blowdown area and gradually expanding it, and Wobbly's method of starting at the total exhaust port area and gradually reducing it, can lead to identical exhaust duct shapes. Here you go Wob, although I suspect you would prefer a single malt .

[andreas]

I too must thank Jan for the flowers , but as I have just reread some posts I must apologize to Andreas if i gave incorrect info about the Motoplat - its been 30 years
is my excuse.

No worries Wobbly, I havn't staked the route just yet.

[husaberg]

I apologize if this is the wrong place to ask, i have been a member on here for quite some time and have been working my way through this thread, but this is only my second post.

I love twostrokes, and i am in many ways stuck in the late 70's - 1980, i'm old enough (51) to remember watching the 50cc and 80cc GP races on TV and they still amaze me.

The 50cc bikes are coming back strong in the Freetech class, and in classic 50 racing, but otherwise they seem like a forgotten era, many bikes are retired to museums and private collections.

I've spent many hours looking for more info, especially about the Garelli 50gp from the last years they raced ( I believe they all had Jan Thiel's engine design) Kreidlers, Minarellis, Derbi 50 and so on, google does come up with nice photos of the bikes, but that's about it. It looks like it's a deep secret of how the cylinders looks like inside, what the portmap looks like, and all the technicall stuff like disc valve timing, port sizes and durations i would love to see and read about and learn what made them so incredible fast.

Can anyone help directing me to where to look ?

Thank you.

http://www.classic50racingclub.co.uk...the-bikes.html

https://www.elsberg-tuning.dk/50ccroadracing.html