ESE's works engine tuner

[FastFred]

Attachment 320857

A fuel injector has a tuning range just like this jet kit has. And just like when you get down to the smallest jet in the kit and still need to go leaner you need a smaller jet kit or injector to move to the next lower tuning range.

That is my problem with the current small injector, it is just not small enough to give me the tuning range required to handle the minimum fueling requirements on high rpm over run on a closed throttle. I need the next smaller injector.

May I ask why you're not using a wideband O2 to tune this area? It would be relatively straight forward with a wideband and a brake dyno.

TeeZee's has been saying, as he sees it, the problem is he needs a smaller injector, the one he currently has can't be turned down enough for the minimum fueling required.

And from what I have seen on here an O2 sensor is better at reflecting the engines "trapping efficiency" than the correct A/F ratio. As I understand it, anywhere away from peak torque a lot of correct A/F mixture escapes a two stroke engine un-burnt and the O2 sensor registers this as a lean mixture because of all the O2 in it.

[Cheesy]

Dont some injectors partially use the fuel pressure to increase the closing speed? If so dropping the fuel pressure may not be that useful. That said if it would work does the ECU have a programmable PWM output that you could use to drive the fuel pump and run it with no regulator?

[TZ350]

Dont some injectors partially use the fuel pressure to increase the closing speed? If so dropping the fuel pressure may not be that useful. That said if it would work does the ECU have a programmable PWM output that you could use to drive the fuel pump and run it with no regulator?

There is no PWM option available on my Ecotrons EFI unit.



But car fuel rails have these sort of fuel pressure regulators. The small pipe goes to the inlet manifold. When the regulator sees less pressure in the inlet manifold it changes the fuel rail pressure so that the relative injection pressure seen at the injector nozzle stays the same and is constant. Whether the motor is in a high vacuum on over run situation or near atmospheric pressure near WOT wide open throttle or maybe even positive pressure in the inlet manifold with turbo boost the injectors are working with a constant relative pressure differential.

I am going to try one of these because currently my fuel rail is constant 3 bar but the injector nozzles see a differential of 3 bar and crankcase vacuum or pressure. So effectively although the fuel rail is a constant 3 bar my injector nozzles are experiencing widely fluctuating injection pressure differentials so I guess the fuel amounts being injected are fluctuating wildly too.

[dmcca]

Why a brake dyno? Then you would be developing an engine for a set of circumstances that it will never see on a race track.
Going through the revs on an inertia dyno and registering revs, torque and lambda simultaneously is an excellent way of establishing an injection map.
Besides, running constant revs on a brake dyno with too little fuel or too much ignition advance may kill your engine, whereas it might survive on an inertia dyno.

When i say brake dyno i mean an eddy current or similar that allows both constant rpm tests and normal 'runs'... Im sure that doing only constant rpm tests is not ideal. Personally I do a combination of both to tune an engine and so far it has worked well for me, especially when tuning the low throttle area that TZ was talking about... in saying that ive only ever had an eddy current dyno, never an inertia-only dyno, and have developed my own methods of tuning without ever seeing first-hand anyone else's process for tuning a two stroke... maybe its a case of ignorance is bliss, however i find my process to be very quick and very reliable for a wide range of engines.
I find that the lambda sensor is a little slow to react at low revs and part throttle. Its fine at higher revs and higher throttle. By holding the engine at a certain rpm point for 3-5sec at each throttle position it gives the readings time to stabilise and gives much better, more repeatable data. I start by doing a range of fixed rpm tests at different throttle openings, with the revs building higher each test... eg 4000, 6000, 8000, etc at 1/8, 1/4, 1/2, 3/4, full throttle ... By doing this you can easily see the areas that need changing (pilot, slide, needle diameter, clip position, needle taper, main jet, etc). If there is a serious problem with the tune you will always catch it before doing damage as youll see AFR's begin to lean out or detonation begin to show before you get too high in rpm. Once ive done basic tuning like this then i do full runs and constant load testing and fine tune if necessary, but these are normally only very minor changes.

TeeZee's has been saying, as he sees it, the problem is he needs a smaller injector, the one he currently has can't be turned down enough for the minimum fueling required.

And from what I have seen on here an O2 sensor is better at reflecting the engines "trapping efficiency" than the correct A/F ratio. As I understand it, anywhere away from peak torque a lot of correct A/F mixture escapes a two stroke engine un-burnt and the O2 sensor registers this as a lean mixture because of all the O2 in it.

Whether the AFR reading is showing true AFR or not doesnt really matter, the numbers can still be used to tune an engine... around full throttle and peak torque it is fairly reliable to use ~12.5:1 and leaner readings below that, down to around 13.5-14:1 at part throttle/low rpm. Of course you still need to use experience and 'feel' to do the fine tuning but the AFR numbers will get you close. Even if the engine is not actually seeing 14:1 at part throttle/low revs, its still a repeatable data point that can be used to tune an engine. Its certainly a lot better than guessing, especially when tuning the part throttle areas.

My main question to TZ though was why he wasnt using AFRs to tune his engine? Since he has employed a lot of technology so far it seems only a small extra step to be using a wideband O2 senor to help with the fine tuning as it will save a lot of the guess work.

[wobbly]

+1 the above.Adding that putting the Lambda in the stinger, seems to be way more stable and repeatable when logging the A/F data.

Using data this way is something that you really dont appreciate how good it is until actually doing it.
Hence TeeZees surprise when I related that every time you change a small item in the engines tune - the dyno result for sure is not telling you
really what you want to know, unless you rejet every time to hit a predetermined baseline.

As Jan Thiel said, most all of the pipe testing at Aprilia was a complete waste of time,when he finally realized alot of the power differences were down
to how the egt reacted to that pipe.
Not that the pipe was "better " for some aspect of scavenging, or trapping efficiency in making more or less power.

[crbbt]

Hey Wob,

I think you would be the man to ask. Is there much difference between a Keihin SPJ and PWK? (with tps and power jet)

I'm almost ready to bring my RS into the early 00's.

I'm tempted to go a dual "power jet" Lectron with one under solenoid control but I'm worried about control over the slow speed jet equivalent. having it set rich enough to not seizing into turn 1 at PI (again) because Im a girl and can't hold my kids bike flat there. then setting it lean enough when I go to a go kart track and burn through rear brake pads.

or is that just adjusting the metering rod length on the lectron?

[TZ350]

... putting the Lambda in the stinger, seems to be way more stable and repeatable when logging the A/F data.

Definitely going to do it this way if there is a next time.

My main question to TZ though was why he wasn't using AFRs to tune his engine? Since he has employed a lot of technology so far it seems only a small extra step to be using a wideband O2 senor to help with the fine tuning as it will save a lot of the guess work.

Already have please see below, I started out trying to get a 12.5:1 A/F everywhere on the map, as you do if you don't know any better. Things weren't going well and I gave it away when it was pointed out to me that it was the short circuiting fooling the O2 sensor into thinking the system was running lean when it was not. It really confused things and it looked like the O2 sensor was not going to be very useful so I discarded it.

But your experience encourages me and it looks like that with a bit more experience myself I might be able to get somewhere with it now I have a better idea of what is going on. But I don't really need it for finding max power now and my low throttle fueling issues seem to be related to injector size and not map adjustment. Don't really feel the need for going back to the complication of an O2 sensor at the moment, but that could change.



Below are my previous efforts with a O2 sensor and EGT.

Attachment 291873

Ok finally got the O2 and exhaust temperature sensors installed.

Ecotrons has been pushing me to do this, they need the Lambda info so they can better help me develop a good Alpha-N map.

No idea if they are in the optimum place but they will do for a start.

Had to change to un-leaded fuel but still have to drop the compression a touch to suit the 96.

Attachment 291872

The air fuel meter and Lambda controller/transmitter.

Attachment 291871

Using the cursors, with Cursor-1 I can see that at N_b 7206 rpm LamWO2 is rich at 0.85 and Cursor-2 lean at 1,247 Lam at 9120 rpm.

Attachment 291875

Now that it all seems to be working I am really looking forward to getting a bit of time on the dyno to play with this thing.

Attachment 292062

With Lambda at 0.76 its a little rich at 11.6K rpm, the Lambda (bottom line) hovers mostly around 0.9 - 1.0 so a little lean for best power every where else.

But look at the Lambda line, there is no big peaks and hollows now, Ecotrons recorded data and data analyzer software is sure a big help with sorting out the fueling.

I am now starting to make some headway with tuning the Beast and I am beginning to enjoy using the Ecotrons small engine EFI kit for two strokes and its 2T tuning softaware.

Attachment 291979

Recorded some RPM and TPS data along with the Lambda O2 sensor.

This is an expanded section of the recorded data with TPS at the top, RPM in the middle and Lambda at the bottom. The curser shows the Lambda is 0.86, rpm 6.5k and TPS 99%.

Attachment 291980

Exported the Alpha-N map to Excel. Using a spreed sheet makes it easy to manipulate the map and keep the steps between cells smooth.

Attachment 291981

The thick blue line is the Lambda and its max lean where its flat on top and the bottom of the dips is Lambda 0.8 - 0.88 ish. The red line is TPS and thin blue is RPM.

By printing out the Alpha-N map and studying the Lambda-RPM-TPS data I can see where to make changes in the table.

Its starting to feel like progress but I have not got so far as to have a worthwhile dyno graph to show off yet.

Attachment 292203

Ok, making progress, that's if you can call getting it wrong progress.

Attachment 292202

Ecotrons has a very clever self tuning feature where you tell the map what Lambda you want at what RPM and the ECU will read the ALM O2 sensor and adjust the mixture for you.

Attachment 292204

The green squares on the map are where the ECU has completed the tuning process and delivered the Lambda asked for.

But you do have to ask for the right Lambda value for the engine. And this is where I went wrong tonight, I made the lower end to rich and eventually after a lot of auto tuning work the motor could not pull the skin of a rice pudding and drag itself into the power band.

On a rolling road dyno you can only do this auto tuning at low RPM and light loads because the Auto Tuning function needs the throttle and rpm to be held steady for 10 seconds or so to work.

The auto tuning feature works better and you can cover more of the map if you can ride on the road and use the head wind as a load or better yet, use a dyno with a brake to hold the engine steady.

Attachment 292205

My mistake was asking for to rich a Lambda at low throttle settings, and having the bike struggling to pickup on the dyno. I had made the map 0.85 Lambda everywhere, I should have stuck with the default map that had Lambda 1 at low RPM and dropping to Lambda 0.85 - 0.82 at max power.

But being able to make planned mistakes is a step better than just making ignorant mistakes and not knowing why.

So .... its progress ...

[wobbly]

Having twin PJ with one solenoid controlled is a great idea.
But when running Avgas be sure to only switch on/off a small ( 35 ) jet.
The tuning with the Lectron needle length is only for what would be normally the pilot/airscrew and slide adjustments ( idle and transition only ).
From 1/4 throttle and up is set by the 2nd needle number.
A PWK is shit ( 3 Hp in 40 on a SKUSA Honda ) compared to an SPJ, but the SPJ is very similar in performance to a PWM as they are the same length.
A PWM is way cheaper, but then you have to add a PJ at then a TPS.
I thought the longer PWK would make better mid, but no free lunch there at all.

[crbbt]

Thanks for your response!

my only concern was parts availability into the future for the SPJ

Might look at modify a lectron for a uni project (and a 12v generator for a cr125)

[husaberg]

Having twin PJ with one solenoid controlled is a great idea.
But when running Avgas be sure to only switch on/off a small ( 35 ) jet.
The tuning with the Lectron needle length is only for what would be normally the pilot/airscrew and slide adjustments ( idle and transition only ).
From 1/4 throttle and up is set by the 2nd needle number.
A PWK is shit ( 3 Hp in 40 on a SKUSA Honda ) compared to an SPJ, but the SPJ is very similar in performance to a PWM as they are the same length.
A PWM is way cheaper, but then you have to add a PJ at then a TPS.
I thought the longer PWK would make better mid, but no free lunch there at all.

Wob the 1999 to 2007 ish Kx125 and KX250 plus a few KTM's and I think Suzukis of the same era (I will have to check the years) have a PWK shorty (PWK-S) is 75mm with TPS and solenoid PJ (36mm 38mm )
http://www.brokenmx.co.uk/media/cata...1/t109-_1_.jpg


Is the SPJ and PWM shorter again or just the same length.

05-11 YZ250 PWK carbs (with TPS)
02-08 RM250 PWK carbs (with TPS)
??-07 KX250 PWK carbs (with TPS)
2000 CR250 PWK (no TPS)

http://www.thumpertalk.com/topic/879...on-infomation/

As far as I know all the PWK bodies from 36mm through 39mm that are made to accept a throttle position sensor (TPS), are of the same length. They will be 75mm inlet to outlet. Some of them don't actually contain a TPS but use the same body, such is the case with the newer KTM's, most of which are 36mm but they used some 38mm's on certain models. I have a 99' KX-250 TPS PWK, and a 06' KTM 250 SX PWK which is the TPS body but doesn't actually contain a TPS. They both measure 75mm inlet to outlet, which is the same as my 03 YZ 250 TPS PWK.

[crbbt]

I just picked up a PWK with the tps and pj off a 1999 kx250 to put into my CR125.

the kx carb is 75mm but i was under the impression that the current PWK's on the ktm's and yamaha's were also 75mm but lack a power jet. at least on the yamaha's

[wobbly]

Yes I think there are versions of the PWK that are short like a PWM or SPJ, but the ones I have seen all have the so called " air striker " fences on the bellmouth
floor.
This may be fine for a MX bike but in every test I have done the power is well down with this system,can it be removed - probably.

[richban]

I just picked up a PWK with the tps and pj off a 1999 kx250 to put into my CR125.

the kx carb is 75mm but i was under the impression that the current PWK's on the ktm's and yamaha's were also 75mm but lack a power jet. at least on the yamaha's

YZ250 PWK's with tps and pj. I have a KX version as well only difference is the power jet connections and the needle in the KX carbs is richer on the tapper. Actually I think the KX version has a slightly leaner slid cutaway.

They work great at the moment on the 300. But really measure 37mm. I will bore them to 39 when I get the new engine mods done.

[KKT]

Hi.

I'm not allowed to start a new thread, so i will risk an eye..and ask here, if inappropriate please delete.

I have been looking in many books about twostroke engines. and also searched on google, but i never found a definitive answer.

Many gokarts run coolant temperatures around 50-55 degrees C, the same goes for outboard engines, and some run even colder.
I have read about many road race bikes, from 50cc to much larger bikes, that also seems to run at these same temperatures.

Why it is so ? Do twostrokes make most the power within this particular temperature ?

Best regards
KKT

[JanBros]

Do twostrokes make most the power within this particular temperature ?

This.
Jan Thiel has tested this at Aprilia, up to even running constant tap water through the cooling system.