ESE's works engine tuner

[husaberg]

Husa , na , the 56 bore compromised the transfers even more.
All to do with corporate pride and who was in charge of R&D at the time.
The dual boost port , big bore was a cockup in every direction , but untill managment changed in 99 and they bought a Czech CNC anemometric flow visualizing rig , suddenly they
went square and changed to 5 port designed on the new machines results.
Susan , as was his nickname at the time , the new head of the race dept told me they could accurately predict a Hp curve shape purely off the flow results , and didnt need to dyno dozens of
cylinders anymore - and his new 5 port design was easily way better than anything else they tested.

Schumae , if you really want to look at a positive direction re rod length then as I said before look at historical results.
The RS125/250 Honda had a short rod forever , untill Honda finally got serious as they wanted desperately to win the final season of GP racing.
Suddenly the new bike appeared with 109 rods and beat the Aprilia due to being just fast enough with Aoyama on board , and the Italian boys all stealing points off each other..
Jans RSA went to 120 , as part of getting a really big case volume , that RVs work well with.

The short rod KZ Modena has won nothing - the TM has always had a 109.8 ( an old mistake in CNC programming they never rectified ) very close to 2:1 and has easily the best record over time.
I wanted to go to 113 with the new homologation R1 but Franco flattly refused , and told me to shutup and stick to pipe design.
The 115 rod Vortex does make more top end power ( probably due in main to reduced bore friction ) but the issue with a reed engine is that you have a catch22 regarding case volume and the reed thickness needed.
Big cases under 1.3 ratio ( due to a longer rod ) do work better with aggresive pipes , but the bigger case has a Helmholtz trend that needs thinner and thinner stiffness petals - these quicly loose control due to
the first harmonic frequency - and thus power drops.

In my opinion people raving on about short rods , powerjets and incomplete burn , are trying it on with techno babble rubbish.
The heat transferred into a pipe is completly dependant upon the combustion variables of compression and ignition advance being optimised to suit the Ex ports interaction with the pipe length being used.
Yes , short rods dwell at TDC differntly than long ones , but both can be optimised to give the best result for that set in stone design variable.
And yes a Powerjet can make it easy to reduce the natural tendency of a venturi carb to go progressively rich over the top of the powerband.
But we have a whole bag of tricks to achieve the same effect in a KZ without one - easily able to hit 680*C in the header at 14800 , if the fuel will allow it.

In 2000 the Yamaha France crew-chief Guy Coulon copied the Honda cylinders, I don't know if this was done with permission of Yamaha or not
Later Yamaha-Japan did the same with the 500cc fours.
They even published a SAE paper about it, incredible!!!!!!!
In 2003 a longer stroke was tried at Aprilia: 53mm bore
The result was less power and more detonation----
Then 52 bore was tried, even less power, and after some tests the piston oin was found, inside the carburetor.
That was the end of Aprilia's long stroke experiments....

Oddly the most successful model of Cagiva 500 GP campaign te V594 ended the season at least as 54x54.
looking at some pics I have they also had models in this period with Honda like bridged Ex ports and flapper ex valves.


What's odd is the Cagiva was known to so very close to the Yamaha YZR500 that parts could be substituted.
but yes maybe just like the 5 valve head and honda with reeds, maybe pride keep them from changing.


I am still not sure that Yamaha had the room for decent transfers and suspect that this might be why they stuck with 6 main transfers
the spacings compared to Hondas single crank were so close they couldn't even fit in the reeds properly.


it seems later yamaha were wider bore centers.

Edit okay Yamaha went bridged in 1997 I did not know this.

[wobbly]

All the Stock Honda spigots as well as a few aftermarket ones I saw had a step at the exit - I knew from my testing on KZ that you get a good top end increase by eliminating that step
such that the spigot end is a sharp edge. I spent most of one night in the tent at Vegas with a drill and a round file modifying one for morning warm up.
The data showed near on 300 rpm extra down the shute - the result was the first Stock Honda win for us.
By the next year I had my own CNC made ones with no steps at all.

Haha Jan - I wonder who the clever dick was at Aprilia who thought long stroke was the way to go.

[jamathi]

All the Stock Honda spigots as well as a few aftermarket ones I saw had a step at the exit - I knew from my testing on KZ that you get a good top end increase by eliminating that step
such that the spigot end is a sharp edge. I spent most of one night in the tent at Vegas with a drill and a round file modifying one for morning warm up.
The data showed near on 300 rpm extra down the shute - the result was the first Stock Honda win for us.
By the next year I had my own CNC made ones with no steps at all.

Haha Jan - I wonder who the clever dick was at Aprilia who thought long stroke was the way to go.

It certainly wasn't me!!!!

[Schumae2]

All the Stock Honda spigots as well as a few aftermarket ones I saw had a step at the exit - I knew from my testing on KZ that you get a good top end increase by eliminating that step
such that the spigot end is a sharp edge. I spent most of one night in the tent at Vegas with a drill and a round file modifying one for morning warm up.
The data showed near on 300 rpm extra down the shute - the result was the first Stock Honda win for us.
By the next year I had my own CNC made ones with no steps at all.

Haha Jan - I wonder who the clever dick was at Aprilia who thought long stroke was the way to go.

Wobbly; thank you for the clarification on the spigot step (I will look into its match up to the pipe).

[wobbly]

I knew that Jan , would love to name and shame the specific idiot , not that it matters to anyone except afficionado 2 stroker historians.

[Frits Overmars]

I wish I could use a carburetor with a power-jet but, the rules say that all fuel must enter the carburetor through the main jet, so that has limited my options..

You've got quite a useful option left: instead of reducing the total fuel cross flow area, increase the air flow to the emulsion tube. Take a look at a Suzuki RGV250 engine (also used by Aprila in their street-250) where solenoids control this air flow in order to keep the exhaust gases cleaner at part-throttle. On more than one occasion it has been an engine killer when these solenoids stuck open, so I advised to disconnect them, but in your case they may come in quite handy.
Mind you, the rules may object to any form of kart engine electrification; it's already a miracle that they don't force you to use flint ignition.

Haha Jan - I wonder who the clever dick was at Aprilia who thought long stroke was the way to go.

That would have been the same dick that reluctantly approved experiments with smaller bores, provided that the original piston forgings could still be used in order to save money. So the possible steps were very limited and the piston skirts became paper thin.

[katinas]

Then 52 bore was tried, even less power, and after some tests the piston oin was found, inside the carburetor.
That was the end of Aprilia's long stroke experiments....

Jan, very interesting to hear this.
Perhaps Aprilia follows Honda s young group engineers experiments with longer stroke, on the first two crank version of NSR 250 ( 52 mm x 58 mm) in 1998. Looks like, idea was to minimize detonation, with unleaded fuel, but max power decreased although acceleration was better.
Interesting, how smaller bore and longer stroke scheme influence mass flow through engine.

[Schumae2]

Thank you Frits! I had not thought of this method of controlling the carburetor, and was unaware of its use in production. Yes; there are rules limiting electrification......Plainly read it seems as long as air fuel ratio and/or ignition timing changes cannot be made by the driver during operation its permissible to have such components / systems that can make those adjustments, but its murky about making those changes on the fly. I have seen KZ engines have a fuel flow valve, that restricts return flow from the diaphragm pump, thats mounted to the steering wheel (driver adjustable / on the fly) at the super-nationals, which would breach the previously described rule.....I will look into methods of controlling a solenoid like described, and scrutinize the rules a bit.

[husaberg]

I posted a pic of the 97 cylinder map above her I the model changes the year before
OWJ1 (1996)

- Adoption of a 54mm bore piston
The major new feature of the OWJ1 spec YZR500 introduced in 1996 was the new engine with a 54mm bore. By squaring off the bore x stroke at 54mm x 54mm, compared to the previous 56mm x 50.6mm, this engine succeeded in boosting top speed through a better balance of power and torque character based on total intake/exhaust efficiency rather than simply raising rpm. This model was also characterized by its forged "powder metal" piston with excellent heat resistance qualities and a new frame design that eliminated the seat rail. Riding this machine, Norick Abe shaved an amazing two seconds off the fastest lap time at the Japan GP preliminaries and went on to win the race for his first GP victory. Loris Capirossi also won a round this year on the OWJ1 at the Australian GP.

https://global.yamaha-motor.com/race...s/yzr500_0wj1/

The year before clearly the triple port.

[TZ350]

Older video but a great shot of Alex Degnes's bike.

[breezy]

so,
Adegnes has got his engine running (you tube) what are the benefits of having a larger exhaust port? just more blow down? being able to raise the exhaust port causing less short circuiting? more area for losses due to size? upsetting scavenging? or is this unknown , as its not been done before.

[TZ350]

Alex Degnes's new motor. First startup.

[wobbly]

I am finishing of the sim results for a 20,000 rpm 35cc RC boat engine and was asked if it was possible to turn the cylinder 90* such that the small end pin faces the Ex on one side and the boost port
on the other . This would give a dead straight pipe out the back of the hull , making a very tidy package .
The new engine design has a reed box added on one side pointing upward under the cylinder like a KZ.
I know there are various pro's and con's with turning the cylinder , but I am most concerned about the ring bulging into the Ex port - sideways, not on a thrust face , but the ring pin
could still be positioned opposite the Ex port.
Plus then the inlet flow will be asymetric , a bit like a RV on one side.
But there will be no small end port linking.
What have I missed as being a good or bad technical reason if doing this .

[TZ350]

Team ESE NSR/GP100 110cc engine well into the "Two Hour" endurance race and leading suddenly could not find a gear.

Darn, .... Blair and Nathaniel could have won that race. Congratulations to Team GPR who took the win.

[TZ350]

Sick Dyno. The Team ESE Dyno has become sick. Apparently there is a keeper battery inside the WinPEP electrical stack that keeps everything alive.

According to DynoJet the battery needs replacing and the firmware re flashing. But they no longer support this legacy model.

Replacing the battery looks straight forward.

But ... Help Needed. Has anyone faced this firmware problem before and can help with advice about getting the stack going again.
.