ESE's works engine tuner

[wobbly]

Constantly amazed at learning new stuff every day.
Who would have thought that Yamaha's $300 road bike 1990 TZR250 3XV cylinder was capable of far superior performance than even their super trick rocking horse shit Sugo special 4TW versions worth 500,000 Yen.
The 3XV has 5 " normal " transfer ports that when configured to the Aprilia layout along with the rotary drum PV that closes all 3 Ex ports , it blows the last and best 1999 4DP - 20 out of the water.
This instantly responds to a 75% duct exit , but likes a very different pipe approach - and yes I swallow my narcissist's pride in stating wrongly that convex rear cones dont work.
In this instance to gain some very hard won overev , all hamstrung by the idiot short stroke - the shallower second section helps to the tune of 2 Hp past 12500, looses a little peak - but giving
a much fatter power band where it matters .

[Pursang]

Nice flat torque curve! Be happy to see that in a high performance 4 stroke.

[jbiplane]

Use a method that YAMAHA patented and is now available. It's very simple

Please give more details what you meant - any link?

[wobbly]

Getting a race 2T to generate a flat torque curve is very much a function of pipe and inlet tuning - all it takes is attention to detail in the results seen in every sim iteration
from EngMod.
Having this in a racebike gives superb " throttle connection " - riders love it when " x " throttle results in "x " power increase over a wide band of torque.
Here is the same result with the CPI 400 Cheetah in a RS250 Cup chassis - it hauls like a train from 8000 out of 2nd gear hairpins and revs hard to 12,000 , blows Superbikes out of the water.
It would be easy to go well over 100RWHp but would then sacrifice all the mid power.

[skako]

Super power band.
The wide power band that is required. Such an engine is easy to drive in city traffic because it has a wide reserve of power under the throttle. The torque characteristic can comfortably satisfy a gearbox with only 4 gears.

[ceci]

Please give more details what you meant - any link?

Tip goes to SwePatrick, who uses a mechanical fuel pump driven by a belt from the TZR250's crankshaft.
The particularity of this system is that it works with variable pressures, in the Aprilia RWS 500 it uses the same pump system (in this one there are no reeds in the intake, since it is by disc, a fuel pressure gauge is used and the CPU needs a mapping with reference to the different "airbox" sensors).
When the intake is by reeds, you do not need a mapping, a fuel gauge, or a pressure sensor in the airbox. Since the injection pressure is given by the rpm and the injection time is given by the reed sensor.
The patent is from Yamaha and it expired years ago.

[ceci]

Please give more details what you meant - any link?

https://worldwide.espacenet.com/pate...g=en%3Ade%3Afr



What I propose is to make a transformation of this method, to adapt it to an injection with a mechanical pump (the working pressure is variable depending on the engine speed). How do you know that the reed valve is open and the spray goes to the engine, or on the contrary, the reed valve is closed and what you do is paint the reeds with gasoline?

[Pursang]

..... How do you know that the reed valve is open and the spray goes to the engine, or on the contrary, the reed valve is closed and what you do is paint the reeds with gasoline?

Modern solution (rather than "strain gauges") A coil is laminated into the reed matrix. A stationary magnet is mounted in reed block wall. Movement of reed, in relation to magnet, changes the inductance in the coil.
Simple microprocessor can then determine position of the reed and whether it is opening or closing. Timing and duration of injection can be managed by mapping.
Fuel pressure "bleed off" can also be used for fine tuning things like high speed 'cruise' conditions.

[ceci]

Modern solution (rather than "strain gauges") A coil is laminated into the reed matrix. A stationary magnet is mounted in reed block wall. Movement of reed, in relation to magnet, changes the inductance in the coil.
Simple microprocessor can then determine position of the reed and whether it is opening or closing. Timing and duration of injection can be managed by mapping.
Fuel pressure "bleed off" can also be used for fine tuning things like high speed 'cruise' conditions.

Good solution.
My suggestion is to make the injection as simple as possible, without the need for maps.

[wobbly]

I think trying to create an " analogue " injection system is ignoring the huge advancements we now have in microprocessor speed and reliability.
Sure , modern auto injection systems still use MAP to control regulated fuel pressure , but as you need an ECU to control so many other variables ( everything from ignition to injector PWM to IAT compensation )
is the mechanical system control going to be fast or reliable enough.
Honda spent a huge amount of R&D on a largely mechanically controlled 2T injection system , as the available processors were not fast or sophisticated enough - but abandoned it as it was no better than a normal carburetor
for most of a race lap.
Its only advantage was fuel efficiency ( irrelevant for racing ) - and outright top speed due to the intake geometry.

[ceci]

I think trying to create an " analogue " injection system is ignoring the huge advancements we now have in microprocessor speed and reliability.

The advances are infinite if we compare them with those that had the Motobecane 350 injection

Honda spent a huge amount of R&D on a largely mechanically controlled 2T injection system , as the available processors were not fast or sophisticated enough - but abandoned it as it was no better than a normal carburetor
for most of a race lap.
Its only advantage was fuel efficiency ( irrelevant for racing ) - and outright top speed due to the intake geometry.

Honda has done a lot of research on injection in two-stroke engines (in all its forms "direct, pneumatic, indirect") and it is she who is accused of being against 2S.

[TZ350]

Looks like I may have got it wrong again. The tongue on the closing side of the rotary valve is maybe more pronounced then it needed to be. Just a sharp edge or at least a smaller tongue, just enough to stop the RV being pushed into the port when closing. Suzuki GP100 (now 110cc) fitted with the much larger Kawasaki KE175 rotary valve cover.

[TZ350]

The other challenge today has been figuring out how to wire an Ignitec ignition to a power valve actuator. It was very straight forward once I understood what to do.

[wobbly]

TeeZee , I must have explained this a hundred times to many people. The simple way to do PV programming is to disconnect the servo power , and just have the 3 feedback position
wires connected to the ECU. With all the cables positioned and adjusted , wind the servo to the down position till you just feel resistance. Read the position voltage.
Then wind the servo to the full up position - read this voltage on the screen.
Program in the two voltages and the up/down rpm and its done.
Make sure to leave the servo in the down position , turn off the ECU power , reconnect the servo wires.
When you fire up the ECU it will cycle the servo full up , then back down.
If you have the tension and voltages correct you can use 50mV for the hysteresis ( Off ) and around 300mV for the I/P, if its not correct the servo actual Vs servo program box will error in red.

[Frits Overmars]

The advances are infinite if we compare them with those that had the Motobecane 350 injection

I remember that Motobecane approach well. What looks like a harddisk was a transparent disk whose light transmittance was variable over the angular rotation of the disk and over the distance from the light-sensitive cell to the center of the disk, comparable to the read/write head of a real hard disk.

Honda has done a lot of research on injection in two-stroke engines (in all its forms "direct, pneumatic, indirect") and it is she who is accused of being against 2S.

The Honda technicians were quite inventive. It was the Honda board that was against the two-strokes and therefore blocked several promising developments. ​