ESE's works engine tuner

[sispeed]

Ronax is doin very well with their EFI Stroker.
Saw them several times racing in classic events and compared to a Suter it is cheap. Ok, not really, but in comparison ;-)
http://www.ronax500.com/en/ronax_tech.php
https://www.youtube.com/watch?v=6qNcttBSw9Y

Regards Siggi

[karter444]

Hi Wobbly
can you tell me when detonation usually occurs in a kz engine . Three possible times could be.
1. pulling hard out of a corner at lower rpm ie 9800
2. when the engine pulls through peak HP ie about 13500
3, at peak engine rpm ie 14800.
it seems most people eliminate deto by lifting the needle so Im thinking it wont be option 3 , but this doesnt mean they are doing it the right way as I know most dont even change jets etc with changes in RAD
cheers Richard

[TZ350]

Ronax is doin very well with their EFI Stroker. Saw them several times racing in classic events and compared to a Suter it is cheap. Ok, not really, but in comparison ;-)

http://www.ronax500.com/en/ronax_tech.php

https://www.youtube.com/watch?v=6qNcttBSw9Y

Regards Siggi

That is great Suggi, thanks. The Ronax500 sounds great and sounds like it comes back on the pipe cleanly after shutting off for a corner. That coming back on the pipe is the hard part with 2T EFI and is where I am having my own problems.

Well it looks like I wont be the first to crack it so hopefully I will be able to post about how it's done so others can experiment with the technology too.

[TZ350]

Ok Kiwibiker, upside down .... why???

It's real easy to get a EFI 2T to run very well on anything over 25% throttle because the airflow is consistently predictable. Predictable air flow makes it easy to get a EFI 2T to drag race out of the corner once its on the pipe.

But because air flow through a two stroke is very much influenced by resonance and the more highly tuned an engine the more the symbiotic resonance waves reinforce each other and the more easily they are disturbed which greatly changes the air flow pattern through the motor and it all becomes much less predictable at reduced throttle settings. This is particularly evident below 25% throttle on a tuned engine. I think there has to be some way to see these air flow changes as they happen and I am looking for it.

The Ronax500 looks like its got the low throttle changeable air flow prediction sorted and the Suter is still struggling with it.

[Pursang]

And Lougher was saying that when he backed off into a corner, it took several seconds to actually " slow down ".

With Braking 'detection' and an electronic throttle it should be possible to cut the fuel and brake with Full (not restricted) engine compression.

cheers, Daryl.

[wax]

Another Blow down question.
Ok we know if you have not enough blow down you ended up with reversing the flow in the transfers and your engine will not want to rev.
I have read where Frits or jan said the more blow down you can get the better. SOOO the big question, how much to to much?
My cylinder clocks up at 204/ 126 so by my calculations thats 39 degrees of blow down. To much ?? I dont know, what is the effect from having to much.

[TZ350]

And Lougher was saying that when he backed off into a corner, it took several seconds to actually " slow down ".

I can only guess but my guess is that they have fueled it for the lowest common denominator of air flow. Leaned it down so much at low throttle settings that its running HCCI on some of the engines combustion cycles as it runs into the corner. They would have leaned it off to try and stop it getting over rich on randomly collapsing air flow cycles.

I think the wave action collapses or picks up unpredictably on closed/low throttle trailing through a corner and the leaning down is to help the engine to clear and pick up again in the drive out from the corners apex. My guess based on my own experience.

One thing I am sure of though, is that you can't apply four stroke fuel injection thinking to highly tuned two strokes.

[Frits Overmars]

I have read where Frits or jan said the more blow down you can get the better. SOOO the big question, how much to to much?
My cylinder clocks up at 204/ 126 so by my calculations thats 39 degrees of blow down. To much ?? I dont know, what is the effect from having to much.

Jan and I both said that, Wax. You can hardly have enough blowdown, but you can have too much exhaust timing, and that may be the case with your cylinder.
For efficient exhaust wave superpostion (read all about it on Kiwibiker somewhere) you'd want about 190° exhaust timing.
Yes, the Aprilias ran 202°, which was a compromise between insufficient blowdown time.area at over 23 m/s piston speed and imperfect optimum wave superposition.
Calculating the blowdown angle doesn't mean all that much; it's the time.area that counts.
The effect of too much exhaust timing can be threefold: loss of work stroke, an increased risk of transfer short-circuiting and the already mentioned imperfect wave superposition.

[husaberg]

I have posted several comments on Suter pages, where all they show is full throttle dyno runs - deathly silence every time.
My spies at the TT, say the thing sounds horrible on part throttle, just like last year.
And Lougher was saying that when he backed off into a corner, it took several seconds to actually " slow down ".
Man, I hope these guys get on top of it,they have had 12 months to test it to death, but all we see is wank pointless full throttle videos.

I can only guess but my guess is that they have fueled it for the lowest common denominator of air flow. Leaned it down so much at low throttle settings that its running HCCI on some of the engines combustion cycles as it runs into the corner. They would have leaned it off to try and stop it getting over rich on randomly collapsing air flow cycles.

I think the wave action collapses or picks up unpredictably on closed/low throttle trailing through a corner and the leaning down is to help the engine to clear and pick up again in the drive out from the corners apex. My guess based on my own experience.

One thing I am sure of though, is that you can't apply four stroke fuel injection thinking to highly tuned two strokes.

My thoughts as well, too lean on the pilot or idle screw can cause a hanging idle where the engine is slow to return to normal speeds in relation to throttle position
Frits mentioned Cagiva also had the overfueling problem on over run common on fuel injected bikes although for some reason they also suffered it even with carbs and they worked around the issue with spacers under the red petals so they never completely closed.

Several riders of the Cagiva 500-4 works racers experienced a painful demonstration of this stubbornness:
When closing the throttle for a corner (a 500-4 will need that from time to time) engine power dropped. But when they reopened at the corner exit.... nothing happened. The reeds had to be opened by the suction of the exhaust pipe, but when there is no combustion, there is no suction. So the riders opened up a little more. And a little more. And more.... And then, at some point, there was once more sufficient combustible mixture in the cylinder to be ignited. The pipe suction returned from its coffee break and the whole two-stroke resonance cycle was reinstated - with the four carbs wide open. That hurt....
The problem was solved by inserting thin strips under the reeds, so they never really closed completely. It messed up the carburation and cost over 10 HP, but it improved both the lap times and the mileage you could put on a rider.Later, because of those carburation problems, Cagiva was one of the first to switch from carbs to injection.

I have mentioned had the same issue occurs with diaphragm pumper carbs on a two stroke where it bogged before suddenly clearing and coming in with a bang.
The only race test of a Cagiva fuel injected bike mentioned the same thing as did Foggy when he tried it.
The KTM 250 GP bike had a fuel injector I believe that only worked on over run, I wonder how they triggered it and why it didn't cause them issues with over fuelling?

If I were Suter, I'd have the main throttles electronically controlled, but always open to 10% (or the lowest the engine can sustain without misfire), then have individual butterflies on each cylinder that snap open as the throttle opens. Say at 2%, 4%, 6% and 8% throttle. Once all cylinders are lit the main throttles open. Easier than trying to control the engine near the misfire limit, have each cylinder either constantly firing or not.

The problem with airflow measurement is the delay. You need to wait for the engine to start pulling the air before you can measure it, then do the ECU calculation routine, then it takes 1ms to open or close the injector. By the time you can make a change to the fuel quantity delivered, the air has already entered the crankcase and the cylinder so you've missed the boat. TPI helps but ideally you want some airflow prediction, be it cylinder pressure, exhaust pulse pressure, pressure as transfer ports open (KTM uses this). Carbs work well because they work in real time, the only delay is the inertia of the fuel in the passages.

Neat idea, The Motogp bikes use auto throttle blippers and they do the same with some throttle bodies not shutting completely.
At times on over run some like a single which I guess some effectively become one.
Its something that would be pretty easy with fly by wire throttles. (they do this to stop the bikes locking the rear wheel as a high tech sprag clutch)

Our new work utes have normal power and economy settings.
They feel hugely powerful in power mode, but very touchy on the throttle.
I suspect the power setting just opens the throttle wider for a given input of accelerator pedal.
much like a quick action twistgrip.

[wax]

Jan and I both said that, Wax. You can hardly have enough blowdown, but you can have too much exhaust timing, and that may be the case with your cylinder.
For efficient exhaust wave superpostion (read all about it on Kiwibiker somewhere) you'd want about 190° exhaust timing.
Yes, the Aprilias ran 202°, which was a compromise between insufficient blowdown time.area at over 23 m/s piston speed and imperfect optimum wave superposition.
Calculating the blowdown angle doesn't mean all that much; it's the time.area that counts.
The effect of too much exhaust timing can be threefold: loss of work stroke, an increased risk of transfer short-circuiting and the already mentioned imperfect wave superposition.

Thanks Frits. I understand that about the exhaust port timing. The issue with this cylinder is its a single exhaust port thats stuck between two studs and so they went high on the port timing to try and get them to run better. Its hard to make it lower so im using what i have. Thanks as always for your help

[guyhockley]

I can only guess but my guess is that they have fueled it for the lowest common denominator of air flow. Leaned it down so much at low throttle settings that its running HCCI on some of the engines combustion cycles as it runs into the corner. They would have leaned it off to try and stop it getting over rich on randomly collapsing air flow cycles.

I think the wave action collapses or picks up unpredictably on closed/low throttle trailing through a corner and the leaning down is to help the engine to clear and pick up again in the drive out from the corners apex. My guess based on my own experience.

One thing I am sure of though, is that you can't apply four stroke fuel injection thinking to highly tuned two strokes.

Carburettored 2 strokes were hard to jet on the island, too, because of the elevation and or weather changes.

[peewee]

Thanks Frits. I understand that about the exhaust port timing. The issue with this cylinder is its a single exhaust port thats stuck between two studs and so they went high on the port timing to try and get them to run better. Its hard to make it lower so im using what i have. Thanks as always for your help

frits is right. you can greatly reduce the working stroke when the exh roof is to high. my philoshepy is make the port as wide as reasonably possible and be sure the passage is of good design. a long time ago i think jan even said he improved blowdown by simply improving the passage. ive seen alot of people make a large window but their passage is crap.

[jonny quest]

https://www.racebikemart.com/adverts...1459369440.php

Perfect for someone's Bucket. Cheap too!

Oring's for cylinders.... shaped ones like Aprilia has in the pics above link.

How would you go about making some?

[F5 Dave]

A snip at 3000 Euro

[Haufen]

https://www.racebikemart.com/adverts...1459369440.php

Perfect for someone's Bucket. Cheap too!

That's about the level you'd pay at serviceaprilia, too, I think.

https://www.racebikemart.com/adverts...1459369440.php
Oring's for cylinders.... shaped ones like Aprilia has in the pics above link.

How would you go about making some?

Ideally, you don't. You just fit a round o-ring with the right length into the curved o-ring groove.

But if you must, o-rings are cast parts, so for about 7 of these RSA cylinders you can officially have molds made at some of the rubber companies and from then on get your custom o-rings for around 20ct a piece or so.