ESE's works engine tuner

[diesel pig]

It was later superseded by a Keihin solenoid valve. Keihin just used it as an open/close valve but with some electronics of their own Aprilia turned it into a pulsating valve (13 Hz). The picture shows those Keihin valves on Simoncelli's Gilera RSA250.

What is the advantage of pulsating the valve? actual I am very interested how power valves are used on modern two strokes, I understand that the ignition timing has to be changed to get the best from the system.

[Frits Overmars]

What is the advantage of pulsating the valve? actual I am very interested how power valves are used on modern two strokes, I understand that the ignition timing has to be changed to get the best from the system.

Imagine the valve passes 60 cc of fuel per minute, but the engine only needs 30 cc. How would you go about that? You could open the valve for 30 seconds and then shut it, but by that time the engine may have drowned.
Open it for one second, close it during one second, open it for one second, sounds more sensible, doesn't it? That is why I quoted the valve's frequency: 13 Hz.
That means it can open and close up to 13 times per second. This again means it could open for 1/13 of a second and close the rest of the second, or open for 12/13 of a second and close during 1/13 s, or everything in between. And of course it can stay completely open or closed; enough possibilities to govern the mixture.

The ignition timing does not have to be changed when you use an electronic power jet. But both the ignition timing and the powerjet timing are means of influencing the exhaust gas temperature. A late ignition and/or a lean mixture both cause a higher EGT, so you can match the exhaust resonance frequency to a rising engine rpm.
And if you have that power jet available, the ignition does not have to do it all by itself anymore, so you can search for a timing that gives a better overall result.

[TZ350]

If you get such a huge difference in power by changing the main, then it was well wrong in the first place.
And yes, an electronic powerjet will add at least 800 rpm of free power to that graph, if switched correctly with the right jet ratios - blowing Speedpro of the planet, unless of course he does what I told him.

The big main was wrong at the top but good in the midrange.

The way the carb has been modified it has greatly increased the signal strength at the main jet. It will take full throttle at about 5000rpm and run all the way out to 13,000 and has cleaned up the area that I made the flappy valve thing for, but don't need it now with this carb.

If I can richen up the mid range I hope to get the mid range power back. But just fiddling with the needle won't do it so I guess an adjustable needle jet from a model aero engine for the power jet adjustment and some way of turning the fuel flow off at higher rpm will be the go.

Because I have an RGV air solenoid, for turning the fuel off to the PJ I am thinking of having a "T" in the power jet fuel line and opening that to atmosphere to kill (stop) the bell mouth vacuum thats drawing the fuel up to the PJ thereby effectivly turning the PJ off.

[Frits Overmars]

To give you an idea of the main jet / power jet ratio: typical RSA-values are main 220, power 120. That means the flow area of the power jet is about (120/220)^2 = 0.3 times the flow area of the main jet. And don't shut the power jet until well past the rpm of maximum power or you will risk a maximum seizure.

[speedpro]

.3 is a large portion of fuel supply to be turning off. I thought it would be a lot smaller like 5% maybe. Or does the valve get pulsed? They use that technique of pulsing a valve to vary boost on turbo engines.

[Frits Overmars]

And now for something completely different: I happened to notice this erection sign ^ . I went back a couple of pages to check and almost everybody appears to have it, except 2T Institute and Grumph. But neither of them are Sheilas, are they? What's the meaning of this?

[Frits Overmars]

.3 is a large portion of fuel supply to be turning off. I thought it would be a lot smaller like 5% maybe. Or does the valve get pulsed? They use that technique of pulsing a valve to vary boost on turbo engines.

Yes, the power jet flow is turned off gradually. And no need to ask for the rpm/flow graph; I do not have it at hand here at home in Holland.

[husaberg]

And now for something completely different: I happened to notice this erection sign ^ . I went back a couple of pages to check and almost everybody appears to have it, except 2T Institute

2t institute is a Aussie you will have to post a pic of one of a farm animal.
Sorry in advance 2T. Thats for the "why is there so few trees in the south island" jibe yesterday he asked if it was "because it is too cold."

yes the symbol means a bloke and they both allegedly are. They possibly are shy, or uncommitted?
Most likely they didn't fill it in as they didn't notice it.

Ps i noticed on the Rumi engine the FCR carb. Any hp advantage or just suited as it was a downdraft?
Also the Uno carb solenoid was unable to be pulsed is that correct?

[dinamik2t]

Hi guys, happy new year!
You have posted very interesting stuff in the last few pages.

My tuning has nothing to do with your races, but I hope my thoughts can be a good influence.
I used to have a manual powerjet Lectron 34 carb and an Ignitech CDI-P unit, which I put on sale last year (not too distant a time ).
I managed to sell them and bought a nwe carb and the Race unit of Ignitech, able to control a TPS and a PJ.
TO be honest, I cheated a little on the carb choise: I had searched once for wobbly in ebay and checked his purchases. There I found the YZ/KX250 Keihin 38 carb, which is about 1cm shorter than conventional PWK, has a TPS sensor and an electronic PJ! Actually, this carb is more similar to their PWM design, I don't know why they named it PWK. Perhaps "k" brand is more established in the community... Anyway.

Here it is:


With its shorter length, I can properly tune inlet length according to Wobbly's advices, at 135mm total, using a 30mm manifold and achieve falling case pressure over rising inlet at the 3rd harmonic! Furthermore, as I measured my case comp ratio at ~1.3, it performs better than the 'small' 34 carb!
It's powerjet solenoid says "Shindengen". I don't know whether it's the same one with rsa's.



I assume that with Ignitech I can only control open/close state over RPM. No pulsating operation as Frits explained above.
Now, I have a question.. Ok, in GP's there's the pulsed PJ. I can only choose where to open/close it and Ignitech supports up to 4 power outputs. The first thing that comes in my mind is to add a second powerjet/solenoid to gain more control over the mixture.
Would that be futile?? Left aside corrections, there is only one point to big-lean mixture and gain EGT/power (at overrev), but if I could bo it more gradually would it better?
Perhaps it would be very troublesome to tune in the end...

As for EndMod now..
Not of importance, but here is the curve I have so far from my 118cc engine. I am somehow pipe-limited, so top-power rpm can't rise any further.
This is pretty much my limit, before detonation. I cannot find any way to improve power with this setup.



It only remains to see whether I can properly tune the mixture to get this power and see how much loss there is.

And now it comes to TZ's results. I believe that the difference in crank and RW power might not be a product of the sim's inaccuracy, but perhaps one of the input data or user predicted input data used for the sim. Such as the Comb. Efficiency, as Wobbly said!
I was once very intrigued by that SAE paper "Simulation of a two-stroke". All those sensors on the pipe.. I love sensors! What a room to be in!
Back in 2011, I also thought that I could do my own testing for some of the sim inputs, mostly temperatures and afr. Use sensors to monitor those variables. For me, it is out of curiosity or passion or whatever, but since you guys RACE, you could do it and use it professionaly! Plus, you have your own dyno!

What I had in mind is this:
I obsiously needed a lambda sensor and an EGT sensor. I got both at low prices from ebay. I might add a couple of temp sensors for head/cylinder monitor in the future too.
Now, I know a few stuff of electronics and both the EGT sensor and the lambda** sensor (or any other sensor), that works with the bikes' CDI, produce voltage signals.
So what I need is a unit to record those signals. That unit is called DAQ in electronics, ie data acquisition. Obviously I also need the proper function to translate voltage data to usable afr ratio or temp values. The second one is no problem, I found over the net. The DAQ, I found some units on ebay too, but my income was short this month to purchase this one too :P
Here's a couple of them:

http://cgi.ebay.com/ws/eBayISAPI.dll...ht_3168wt_1270
http://www.ebay.co.uk/itm/USB-I-O-Da...#ht_651wt_1037

And here's a cheap o2 sensor (they also have with 2/3/4 wires):
http://www.ebay.com/itm/New-DENSO-Un...#ht_500wt_1054

Ah, forgot to mention. Last month I also found a great deal of 4 NGK 6254E plugs from KX125 and one 7376! The second one has a significantly thinner ground/side electrode compared to the KX ones!
And they both have very thick washers compared to conventional B-plugs. Or is it threaded length? I haven't really measured.





** I wonder why there is the B between 'a' and 'd'.. The word describes the greek letter for L, which we pronounce lamda. No b!
And sorry, huge post!

[2T Institute]

And now for something completely different: I happened to notice this erection sign ^ . I went back a couple of pages to check and almost everybody appears to have it, except 2T Institute and Grumph. But neither of them are Sheilas, are they? What's the meaning of this?

It flags who's been purchasing Viagra online.

[2T Institute]

2t institute is a Aussie you will have to post a pic of one of a farm animal.
Sorry in advance 2T. Thats for the "why is there so few trees in the south island" jibe yesterday he asked if it was "because it is too cold."

yes the symbol means a bloke and they both allegedly are. They possibly are shy, or uncommitted?
Most likely they didn't fill it in as they didn't notice it.

Ps i noticed on the Rumi engine the FCR carb. Any hp advantage or just suited as it was a downdraft?
Also the Uno carb solenoid was unable to be pulsed is that correct?

Stray dogs would have go a long way to find a tree to piss on ! Was a serious question BTW


Dynos, I look for a flat as torque curve possible with the power roughly a 45deg line upwards hold peak for as long as possible and 45deg down on the over rev. Makes it an easy bike to ride fast. All has to match the gearbox though

Dyno v's Sim, even with the rickety old Mota sim the shapes of the curves matched which told me the data I input was correct, With EngMod if you can expect sim -15% that's s hell of a good start, if you don't get that look jetting and ignition.

[Frits Overmars]

Ps i noticed on the Rumi engine the FCR carb. Any hp advantage or just suited as it was a downdraft?
Also the Uno carb solenoid was unable to be pulsed is that correct?

Your yellow text makes me think you chose a dark background, huh? Mine is white; thanks for the headache .
Yes, the FCR carb was chosen because it enabled us to use a dead straight inlet tract on the Rumi engine.
The Fiat Uno unit was not a solenoid; it was a stepper motor; a rotating device. And stepper motors only function when pulsed.

[dinamik2t]

The Fiat Uno unit was not a solenoid; it was a stepper motor; a rotating device. And stepper motors only function when pulsed.

It's like this I imagine..
Lots can be found under the name 'idle control valve' (not necessarily fiat).

[Frits Overmars]

Lots can be found under the name 'idle control valve' (not necessarily fiat).

When in Italy.....
Makes me wonder: what automotive industry have you guys got in NZ?

[dinamik2t]

Eh, yes. Obviously Aprilia used Fiat's due to nationality. I would proudly do exactly the same!
I wanted to point out that one shouldn't search solely for a fiat motor, as there are also renault, mitsubishi, rover etc etc. And italians' are a little spicy in prices.