ESE's works engine tuner

[Sketchy_Racer]

This isn't going to be a track bike. Bottom and mid are good advantage.

So do I press apart the centers and rephase for 180 firing. I wonder how bad crank harmonics would be, and how complicated it would be to change ignition to fire correctly

The crank would tear itself apart on startup I suspect. The NSR cranks are beautifully designed but only just man enough for the job from what I have learned.

[TALLIS]

are you running a tps on it?

From what I have seen of the throttle design, maybe not. Would it be worth testing with a conventional butterfly efi throttle body with tps, even if injectors are mounted elsewhere?

[ief]

Was looking at a friends setup today (yamaha fs1 rotary 65cc streetbike) whitch had some problems and made power to high in the revs so not to streetable etc etc...

Anyway, bin playing around, suddenly thought i'd try a whole different exhaust slightly inspired by Neels his example and...

I think this could be called a bell shape torque curve

Wonder how it would translate into the real world, as allways, haha.



(how it was and what I made of it)

[TZ350]

are you running a tps on it?

Yes. Running a TPS vis RPM ... Alpha-N map



The next step is to try this Ecotrons throttle body with its injector behind the throttle plate.

[wobbly]

No power below 7000, then it doubles from 6Hp to 12 Hp in 2000 rpm.
I think it may be even harder to ride than the other more linear curve, both sure arent ideal.

[mr bucketracer]

Yes. Running a TPS vis RPM ... Alpha-N map



The next step is to try this Ecotrons throttle body with its injector behind the throttle plate.

its like its fueling on the running down of the rpm of the engine and giving it fuel at rpm instead of cutting to a idel of the tps off the gas , need to get a A/F reading when running down

[ief]

No power below 7000, then it doubles from 6Hp to 12 Hp in 2000 rpm.
I think it may be even harder to ride than the other more linear curve, both sure arent ideal.

To much of a bell curve ai... indeed no change below 7000, better suited for a cvt then perhaps (?)

Back to it it is then.

[TZ350]

its like its fueling on the running down of the rpm of the engine and giving it fuel at rpm instead of cutting to a idel of the tps off the gas , need to get a A/F reading when running down

Yes I agree, there is something wrong with the fueling at high RPM low TPS.

This is a small part of a chart recording what the ECU is doing during a dyno session. It can be seen in the chart that the small injector responds Ok to changes in the TPS.



Inside the box.
Top line is RPM.
Blue is TPS.
White is maximum injection time available at that RPM.
Purple is the small injector.

At the left.
It can be seen a section of zero TPS with the RPM running down. The small injector can be seen at its minimum MAP value and the big injector is at zero output.

From looking at a lot of these charts I can see that the RPM trace becomes increasingly erratic when the injection time is less than a third of the maximum available injection on time. A third of maximum possible injection on time is about the same as the transfer open time so I am guessing the transfer period is heavily involved somehow.

Anywhere the injection on time is less than the transfer window open time the RPM trace becomes erratic and increasingly erratic the smaller the injection on time compared to the transfer window open time. This erratic RPM is most noticeable when the TPS is less than 20% and that is where the injection on time is very much less than the transfer window open time.

To a lessor extent this is also true for the big injector too. I think the low load problems are possibly about erratic fuel mixing and maybe the whole fuel charge being blown right through and out the exhaust port or not inducted at all and maybe even building up as a super rich puddle in some hidden corner of the crank case.



It has been a bit of a group effort, hopefully by injecting just behind the throttle plate we will get better mixing , smoother running and a better pickup from a closed throttle.

Anyway, here is hoping, the plan is to try this throttle body with the small injector for improved fuel homogenization, for better slow running and over rev pickup.

Thanks guys, I am looking forward to trying it but it will probably be next week before I get a chance. .......

[MotleyCrue]

And in the work I have done on the 180* 2:1 pipes the best result was with the Ex at 200*, so that limits its applications.
And then there was the idea of cutting the pistons short over the exhaust port.
This made a shit load of extra power - but would be impossible to jet without fuel injection or pumper carbs.

Was the jetting a problem at high rpm or midrange, too lean or too rich, or was there more to it than that ? If jetting was set good for max power and torque then at what other conditions would the mixture be all out of whack and would it be too lean or too rich under these conditions? Also too lean or too rich according to an EGT reading or according to a lambda reading or according to damaged parts?

[Flettner]

Yes I agree, there is something wrong with the fueling at high RPM low TPS.

This is a small part of a chart recording what the ECU is doing during a dyno session. It can be seen in the chart that the small injector responds Ok to changes in the TPS.



Inside the box.
Top line is RPM.
Blue is TPS.
White is maximum injection time available at that RPM.
Purple is the small injector.

At the left.
It can be seen a section of zero TPS with the RPM running down. The small injector can be seen at its minimum MAP value and the big injector is at zero output.

From looking at a lot of these charts I can see that the RPM trace becomes increasingly erratic when the injection time is less than a third of the maximum available injection on time. A third of maximum possible injection on time is about the same as the transfer open time so I am guessing the transfer period is heavily involved somehow.

Anywhere the injection on time is less than the transfer window open time the RPM trace becomes erratic and increasingly erratic the smaller the injection on time compared to the transfer window open time. This erratic RPM is most noticeable when the TPS is less than 20% and that is where the injection on time is very much less than the transfer window open time.

To a lessor extent this is also true for the big injector too. I think the low load problems are possibly about erratic fuel mixing and maybe the whole fuel charge being blown right through and out the exhaust port or not inducted at all and maybe even building up as a super rich puddle in some hidden corner of the crank case.



It has been a bit of a group effort, hopefully by injecting just behind the throttle plate we will get better mixing , smoother running and a better pickup from a closed throttle.

Anyway, here is hoping, the plan is to try this throttle body with the small injector for improved fuel homogenization, for better slow running and over rev pickup.

Thanks guys, I am looking forward to trying it but it will probably be next week before I get a chance. .......

On these low loads, muck around with the injection timing, I found it very important to have the small pocket of fuel delivered at just the right time. What time? I don't know, just adjust it around and see whats happening. You should find a sweet spot where the unusual exhaust noise (talked about both here and with my experiments) goes away. Large on times don't matter so much. On my 350 the difference was gutless to powerful (bottom third throttle) with no fueling changes, only timing.

[wobbly]

Cutting the pistons short over the exhaust made it blubbery rich at low rpm, then it would completely die on transition
off the idle circuit due to being lean.
Once this was fixed it became very rich in the mid band as it came onto the pipe,but at part throttle the same rpm was so lean it would die again,then it was super lean on top.
Getting all this dialed in was VERY hard work with pumper carbs, but as we had good egt and Lambda data from a " normal " running
engine prior to doing the mods we knew what numbers we should have been seeing.
This is why I have been banging on at TeeZee about getting some useable data for his engine, when it is running well, so you know exactly what direction you should be heading in.
The pumper carbs have such a huge number of variables that can be tailored specifically to affect a certain air flow and throttle opening - only
if you know exactly what you are doing, then even the most weird fuel curve can be achieved.
No way would I even attempt to jet a normal venturi carb to run using that piston mod.

[MotleyCrue]

No way would I even attempt to jet a normal venturi carb to run using that piston mod.

I don't think I understand technically why the mixture would vary so much with a cut piston when running a normal carb, at least for a reed engine. Was this a reed valve engine?



What if the engine had of been running on methanol, since there is good tolerance to being too rich, could a regular carb be made to work then?

Aren't all pumper carbs 4T carbs or are there some 2T pumper carbs?

[jonny quest]

TZ350, EFI is very sensitive to TPS setting. Do you have a standard you are sticking too?

[wobbly]

Yes of course running Methanol would make jetting any type of carb way easyer.
The mixture was being affected by pipe pressure when the piston was at TDC,exactly when the reeds are open and case inflow from the carb is highest.
And yes I think the reeds may have been helping some.
The engine I did the piston cut job on was a SeaDoo 951 running in a stock class at the World Champs in Lake Havasu - and yes we won, and no the trick was never detected.
Pumper carbs can be run on anything, but I havnt seen one with an accelerator pump so it may be difficult to get snap throttle response on a 4T - even with an aux venturi system.
Nearly all 2T engines ( sea,snow,kart,chainsaw ) use pumpers, and I personally have never seen one used on a 4T, but there may be classes I know nothing about like Briggs in USA that use them ?

[TZ350]

On these low loads, muck around with the injection timing, I found it very important to have the small pocket of fuel delivered at just the right time. What time? I don't know, just adjust it around and see whats happening. You should find a sweet spot.

Will do. Currently running 180 which seems to work for the big injector. I already have tried 0 - 90 - 180 - 270 for the small injector , but will try a series of much smaller steps.



I now have the Ecotrons EFI throttle body with TPS and Injector all setup to go. It is a conceptual test and if this works better with the small injector firing behind the throttle plate I will see how I can get an injector installed like this behind the ball valve throttle so I can put it back on, I like that ball valve throttle. Dyno is booked for the next few days, so maybe get to try it next week.