ESE's works engine tuner

[TZ350]

- our slow tracks (kart tracks) have some very tight corners, the four strokes drive out of these corners much better making them very hard to beat.

Now that my friend, sounds like an excuse of some sort.

My motor, Dave's bike, and currently Gary riding it. Despite the power it makes, currently less than 30hp, it seems to not have any real advantage over a lesser 4 stroke. It takes a moment to get up and boogy even when well into the powerband revs if the throttle has been closed.

In a similar situation the 150 4 stroke has a more immediate transition to power. The result is that in between corners where you could give it a little squirt the 4 stroke pulls away a bit.

I have noticed the same thing with my stroker, a 4-Stroke that was behind when we are apexing a corner can just get a wheel in front when we both start turning the power on again.

Frits has talked about the wave action in the 2-Strokes pipe collapsing when the throttle is shut and the revs drop and when you open the throttle again you get the sound back straight away but it take a few moments more for the wave action and power to build up again, I guess its that, that is allowing the 4-Strokers to edge a wheel in front exiting corners and is most evident on a cart track.

[TZ350]

Ok ... I have machined the cylinder up for the injectors and now figuring how to mount the common rail. The piece of common rail was cut from a Vtec Civic.

The current plan is to use three IWP048 215cc/min injectors, the ECU will fire the middle one only until it starts coming onto the pipe then the ECU will swap over to the out side pair untill peak torqe when it will bring the middle one in again.


http://competitionsystems.co.uk/product.php?id=145



Maximum fuel flow is about 250cc/min but as we have to deliver it in 120 deg or 1/3 the time available we need about 750cc of injector flow. This set up will have a variable common rail pressure, as the power goes up so does the pressure in the expansion chamber and with the fuel pressure regulator connected to the chamber the common rail fuel pressure will also go up during peak demand.

[richban]

I have noticed the same thing with my stroker, a 4-Stroke that was behind when we are apexing a corner can just get a wheel in front when we both start turning the power on again.

Frits has talked about the wave action in the 2-Strokes pipe collapsing when the throttle is shut and the revs drop and when you open the throttle again you get the sound back straight away but it take a few moments more for the wave action and power to build up again, I guess its that, that is allowing the 4-Strokers to edge a wheel in front exiting corners and is most evident on a cart track.

Anyway enough of the four stroke banter rubbish. Whats the best fuel pre mix for me to run my new un restricted RGV 250 on. Stock everything at the mo. Just un restricted controller. Aprilia version.

[speedpro]

This set up will have a variable common rail pressure, as the power goes up so does the pressure in the expansion chamber and with the fuel pressure regulator connected to the chamber the common rail fuel pressure will also go up during peak demand.

I'm not fond of that idea. You have introduced a variable that is outside the control of the ECU.

[richban]

I'm not fond of that idea. You have introduced a variable that is outside the control of the ECU.

Ahh ok. I just figured I should not rely on the oil pump. Save weight and all that. OK then best oil to use?

[Frits Overmars]

As i see the cooler running 85% ethanol to be a huge advantage on the thermally inefficient air cooled 125cc 2 stroke vs the liquid cooled open carbed 100cc 2 stroke. I base this on the 85% ethanol mix (using my maths) to have a assumed latent heat of evaporation of around 368 BTU/pound (ethanol is assumed to be 410 BTU/Pound with petrol being around 135 BTU/pound.
The may not seem significant, but the correct E85 mixture will end up burning 1.53 times as much fuel. So it will be removing the EQ of 4.17 times as much heat as petrol Yet only adding from its burning 8.5% more heat than petrol.

I cannot find anything wrong with that, apart from you forcing me to think about air-cooled racing two-strokes, which I intended to avoid forever .

[Frits Overmars]

.... This set up will have a variable common rail pressure, as the power goes up so does the pressure in the expansion chamber and with the fuel pressure regulator connected to the chamber the common rail fuel pressure will also go up during peak demand.

What if the engine has one single misfire?

[Frits Overmars]

I have noticed the same thing with my stroker, a 4-Stroke that was behind when we are apexing a corner can just get a wheel in front when we both start turning the power on again.
Frits has talked about the wave action in the 2-Strokes pipe collapsing when the throttle is shut and the revs drop and when you open the throttle again you get the sound back straight away but it take a few moments more for the wave action and power to build up again, I guess its that, that is allowing the 4-Strokers to edge a wheel in front exiting corners and is most evident on a cart track.

Scooter riders have a similar problem: when they close the throttle, the transmission goes into a longer ratio, so crankshaft revs drop. My advice to them: do not close the throttle completely, keep the engine pulling, and take engine power away by using the rear brake. Not every rider can master it, and not every rear brake can endure it, but it does give better corner exits.

[Flettner]

Frits, whats the real reason twostrokes have been pushed out? I don't bother watching GP any more.
Same in MX, now same at trail rides, the twostroke is becoming an endangered species! All the young guys now only ride fourstroke and subsequently have no idea how the engines work because they just pay someone else to rebuild them, perhaps the rules should be that the rider must rebuild their own bikes. Soon twostrokes would be back. Where are we headed? Or am I just old and got my head stuck in the sand?

[Flettner]

I pipe my pressure reg to the chamber, just don't misfire!
Just like the in a car where the pressure reg is connected to the inlet manifold, which is influenced by the turbo exhaust pressure / load.

[TZ350]

What if the engine has one single misfire?

Not a lot I expect, I expect any pressure variations can be damped out.

[TZ350]

Had Buckets4me's RG50 on the dyno today.



14 rwhp at 13,500 rpm.

[jasonu]

Fuel isn't really gonna change much
Well at the gp the bike with the least amount of power out of the top 7 bikes won so I think we other things to worry about than fuel I think nathaniel has 20hp maybe 21hp
Which out off these engine types has the biggest hp advantage in a tuned form for road racing.

125 Air cooled 2 strokes (24 mm carb max)
100cc Liquid cooled 2 stokes (open carb)
158cc Air and Liquid Cooled four strokes (open carb)

[/QUOTE]

It is not all about the hp numbers. Nathaniel and his bike have a combined weight of around 50kg less than the opposition. Nathaniel rides pretty good too.

[Flettner]

Use a pressure wave modifier.
A small hole out of the chamber.

[TZ350]

Good idea, thanks.