ESE's works engine tuner

[lodgernz]

Interesting discussion, thanks to all. Some of it makes sense )

A quick question Wobbly: Do Lectron carbs have a shroud?

[wobbly]

No, Lectrons have no shroud nor do they have any air correction.
The fuel curve is set entirely by the flat on the needle , and its that system that gives them incredible fuel atomization.
I tested this something like 30 years ago , using what was then a real trick VHS tape camera.
Pulling air thru the carb on the flow bench ,I videoed a Mikuni Powerjet off a TZ and a 38 Lectron.
Playing it back in Slo Mo you could see huge globs of fuel slopping out of the emulsion tube on the Mik ,but a real fine mist exiting the Lectron.
I always believed that the later model carb, called Blue Magnum was better as it had an air corrector jet.
But when you dyno a Lectron using Lambda ,the A/F ratio is all but perfect the whole time once the needle and powerjet are set correctly.
A " perfectly tuned " Mikuni is all over the place.
Smart Carbs use the same tech , but have cracked the huge issue of varying mixture with altitude as well.
We tested a winning Quad at Pikes Peak ,and the A/F was at 12.8:1 at the bottom, and 12.8:1 at the top - I couldn't believe it.

[tdc211]

Been playing on the new 105.
33hp and honestiy it's the easiest /best curve
33hp i have done. Not even pushing any port numbe6rs on it yet. Only 85 degree main ex port and 90.5 subs. Runs on pump.

Now the question is why? Tried 4 pipes. One was best by far
Has a good ex tunnel. And the new tranfers make my modified tranfers look big and pathetic in shape.
Tranfer volume is extremly small. Smaller than my modified cylinders by quite a bit
I can tell it less short circuit by alot.

Maybe some of you can use the chord or % on ex to tranfers to compare. I Can tell you the stock cylinder sucks here!

[peewee]

just a observation here. appears the large inner wall tea cup radius is all but gone. wonder what affect that had

[tdc211]

They flow way more than sta says.
I know wob probably give me grief on that statement.
But sta is from 1996 blair book far as i know

[peewee]

Saturday I finally got to take the old shitter to one of the largest sand hills in the united states. im still amazed this thing is holding together and hasn't given me a single problem ever. starts right up in two kicks everytime, tranny shifts perfectly even though the gear ratios are some of the worst ive ever seen, which meens theres only three useable gears. spending time sorting out the fuel flow into the carb really paid off, there was definatly enough flow to go up the hill . burned through 4.4L nitro and 8.1L methanol. unfortunately im not a pro camera man so youll have to click the full screen button

[husaberg]

No, Lectrons have no shroud nor do they have any air correction.
The fuel curve is set entirely by the flat on the needle , and its that system that gives them incredible fuel atomization.
I tested this something like 30 years ago , using what was then a real trick VHS tape camera.
Pulling air thru the carb on the flow bench ,I videoed a Mikuni Powerjet off a TZ and a 38 Lectron.
Playing it back in Slo Mo you could see huge globs of fuel slopping out of the emulsion tube on the Mik ,but a real fine mist exiting the Lectron.
I always believed that the later model carb, called Blue Magnum was better as it had an air corrector jet.
But when you dyno a Lectron using Lambda ,the A/F ratio is all but perfect the whole time once the needle and powerjet are set correctly.
A " perfectly tuned " Mikuni is all over the place.
Smart Carbs use the same tech , but have cracked the huge issue of varying mixture with altitude as well.
We tested a winning Quad at Pikes Peak ,and the A/F was at 12.8:1 at the bottom, and 12.8:1 at the top - I couldn't believe it.

Edmonson carbs
· 1968-1969: The Lake Injector prototype and final production model carburetor.
· 1970-1971: The Pos-A-Fuel prototype and final production model carburetor.
· 1971: The Pos-A-Fuel with remote float bowl production model carburetor.
· 1973-1974: The Lectron prototype and final production model carburetor.
· 1976-1977: The E.I. Prototype and final production model carburetor.
· 1978: The Blue Magnum production model carburetor.
· 1981-1982: The Qwik Silver prototype and production model carburetor.
· 1993: The Qwik Silver II production model carburetor (sold to Edelbrock)./size]

The red Edmonson story is here
https://www.kiwibiker.co.nz/forums/s...post1130160524

[Muhr]

The history of the Rotax is that they used the FN 4 stroke tube in the early model engine ( with a shroud as well ) then when the EVO kit was introduced the FN 266 was
dumped in favor of a " normal " DP 267 with a shroud - same setup as a KZ engines carb..
During the engines life various shrouds were introduced , and we mixed them up to get the best results ,but as I said Mr Tech finally got onto us and specific shroud heights are now fully specified.

At the time I ran around on euro challenge, modifications of the "shroud" were occurring, both shortening and even pulling up and twisting it a bit to adjust the emulsion air flow, like an air screw for main. the first time I saw that they checked it with a jig was in Angerville in 2011 after a qualifying if I remember correctly

[tdc211]

just a observation here. appears the large inner wall tea cup radius is all but gone. wonder what affect that had

Think as far as air flow thru a pjpe/duct. The new shape is superior. Not just the roof angles and inner radius, But the port floor ,by the bore as well.

[peewee]

Think as far as air flow thru a pjpe/duct. The new shape is superior. Not just the roof angles and inner radius, But the port floor ,by the bore as well.

oh the smaller vinamolds were better? i thought you meant the hogged out molds were better. misunderstanding

[tdc211]

oh the smaller vinamolds were better? i thought you meant the hogged out molds were better. misunderstanding

Yes. smaller is the new one. I have tried many attempts to make old cylinder better . But i never pushed the port floor angle as far as the new cylinder.

[husaberg]

I've often wondered how accurate is the long-accepted mantra surrounding carburettors.
Forever, we have been told that the main jet only controls the last 1/4 of the throttle opening, as shown in this widely-published diagram and others similar.
Attachment 338807


This doesn't seem to make sense. Is there some other secret fuel circuit that I'm missing, or is venturi action somehow massively variable throughout the opening?
I note that the needle jet tube has tiny holes in it, but these are in an area that is linked to the atmosphere in the bellmouth, so don't appear to be a fuel source.
Clearly the amount of fuel drawn through the jets by venturi action will increase as the air flow speed through the throat increases, but that doesn't explain why the needle/jet area continues to increase past the point where the main jet has apparent control.

Please discuss...

The answer is the the fuel circuits as marked on many diagrams are not cut and dry like the diagram show them to be.

they have massive overlaps in the area that they effect the carb size also has a dramatic effect on the fueling ie a smaller than ideal carb will readily enriches past peak revs While a bit too large carb one often doesn't.
Also other circuits effect the fueling as well as the shroud height does the stages of the needle tapper and the air control circuits effect areas hugely.
Thats without going into the volume and shape and length of the underside of the slide as well.

read through Robinson and Bell and have a look at cameron is the best i can say.

most i can say to start with float level then the needle jet and get that right first.
Pretty sure its even in the first post of the thread
I posted a nice tuning from scratch a while back. but i cant find it.
But as wob said the Lectron style carbs dont have such wide overlapping circuits
Plus as Flet sdaid neither does EFI you can change the fueling at any point rev or throttle opening you whish

[lodgernz]

Thanks Husa. Good stuff as usual.

[TZ350]

.

Plus as Flettner said, EFI you can change the fueling at any point rev or throttle opening you wish

I just love EFI.



Cross drilling my crank in preparation for the new be spoke crank pin and direct oiling for the big end. I cant wait to get this lot back together so I can get on with my EFI development. Very excited as the new Arduino based Speeduino EFI's CPU 2S software is coming along very nicely. Once it is up and running the next move will be pick and hold crankcase MAP reading.

NSR110 dyno curve.

Power valve curves. below is my NSR110 power valve curve. I have no idea what they should look like.

NSR110 PV curve.

Does anyone know what a PV curve should look like because I have made a better longer flatter fat torque curve with my 28hp air-cooled cylinder that was just a big gaping exhaust port without a power valve. And I expected the same sort of flat torque curve with the PV.

air cooled dyno curve.

I have cracked 31hp with my air cooled but 28 proved more thermally reliable.

[F5 Dave]

Just finished prepping dinner for tomorrow TexMex.
It will marinade in fridge. Won't put it on till 10am.

This is what I'm listening to.

https://m.youtube.com/watch?v=6HJGIhpsN5Y

With big dirt bikes it is incredible how much influence the needle has. On the bucket I need just off idle to be real progressive to control the front. Then transition to mainjet in 0.5 seconds.

Just put an AS2 carb on the GasGas 300 replacing the AS1 with NEDJ needle. Hesus what a stella difference. You've got to take up this dirt bike thing just for an excuse to ride more 2 Strokes. Fanbloodytastic.




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