ESE's works engine tuner

[TZ350]

Rode F5 at Tokoroa last Sunday. Great hopes of glory. Reality put paid to that ......

[pete376403]

I had a look. Very impressive bit of work.

Still using carbs, though - show him you EFI setup

[SwePatrick]

As sketched I would think the biggest difference impacting performance would be in the length.

Yes.
And going with Blairs variant makes my intake very long, i want to keep it very short as i had great luck with short intakes before.

[TZ350]

https://www.facebook.com/rimarmotors

I had a look. Very impressive bit of work.

Still using carbs, though - show him you EFI setup

Two Stroke EFI. https://www.kiwibiker.co.nz/forums/s...2T-EFI-Project

[pete376403]

Two Stroke EFI. https://www.kiwibiker.co.nz/forums/s...2T-EFI-Project

yabbut - i meant show that to the developer of the rimac

[Wos]

Rotax 124 rotary valve inlet

The crank web is camfered sharp.
Think bad for the inlet flow...

Better rounden that ?
If yes...

One complet radius?
2 small radiuses to keep volume of crankcase nearly untouched?

Bottom of inlet duct ending is sharp too...what to do there? What uses cranks rotation influences on flow in the best way...?

Thanks..Dankeschön

Grüße Wolfgang

[Frits Overmars]

Rotax 124 rotary valve inlet. The crank web is camfered sharp. Think bad for the inlet flow... Better round that ? If yes, one complet radius? 2 small radiuses to keep volume of crankcase nearly untouched?
Bottom of inlet duct ending is sharp too...what to do there? What uses cranks rotation influences on flow in the best way...?

I don't remember chamfers on the 124's crankwebs. But then it's literally half a lifetime ago.
I'd give the chamfers a radius, but not one complete radius, as that might remove too much material from around the big end pin bore. You do need stiffness there.
I'd leave the sharp bottom of the inlet duct alone. But you might radius the side walls of the duct.
Don't worry about increasing the crankcase volume. In fact increasing it may be a good thing.

[Wos]

I don't remember chamfers on the 124's crankwebs. But then it's literally half a lifetime ago.
I'd give the chamfers a radius, but not one complete radius, as that might remove too much material from around the big end pin bore. You do need stiffness there.
I'd leave the sharp bottom of the inlet duct alone. But you might radius the side walls of the duct.
Don't worry about increasing the crankcase volume. In fact increasing it may be a good thing.

Frits!

Many many thanks for yor answer and tips!

Crank is cleaer, that we dont should weaken it!...as there is not much Material round

But i am so so confused about my conclusion to your text now...and before text expertices...do not find clear conclusion for me...

Maybe read back would help...maybe your next help!
Or ask without shame

What to do with conrod length? Aiming to longer one to increase volume by length conrod?

Or better increasing case volume by taking off Material on crank webs or case inside?

Still confosed by the fact that there might be my missunderstandings...no clear view...read back...once more...eyeyey...

SOS Frits ! ��

Thanks wolfgang

PS...not only for frits Did Saturday testings for liedolsheim...gained "some" reves by ....... catch us!

[Wos]

Hello together ✋

My personal view now to the long intake duct of the Rotax 124.

Thinking about a subwoofer as my model to undersand

Verry simplyfied piston is the speaker...box vomume is case volume...reflex tube is long intake duct.

If i have a very long reflex tube, that i cant change, have to increase volume of box, to come closer to frequency of reflex tube

If case volume would be zero you can restore zero mixture.
In a big elastic volume you can store a lot more mixture and energy, the process of filling this is long...

Yes there is a next thing the pipe resonance...partly coonnected with case...this i left beside
The closing of the door too...

This is my personal simple picture in the moment now frits

Critics welcome✋ ��


Open to learn and understand better ��

Thanks

Wolfgang

[Wos]

Hello together

Rotax 124

Using crank spin better with halfside radiused bottom of inlet ducts end?

My idea

Inlet is in axe above of crank center
One half of webs intersetion is spinning towards duct, the other half downwards case.

Idea is only radius the downward side of duct end...to ease the downstream finding better down the case, by lower turbulence

Second effect could be, that inlet flow in inlet direction would be less disturbed ...lower turbulence too

Good idea?

Thank you

Wolfgang

[JanBros]

my opinion : don't (as Frits already said). you are rounding the crank web so it can flow better over the web. by rounding the bottom of the duct, Coanda-wise part of the mixture will follow it and as a result hit the web and cause turbulence, exactly the thing you were trying to avoid with rounding the web.

[Wos]

my opinion : don't (as Frits already said). you are rounding the crank web so it can flow better over the web. by rounding the bottom of the duct, Coanda-wise part of the mixture will follow it and as a result hit the web and cause turbulence, exactly the thing you were trying to avoid with rounding the web.

Hey jan,

What a pleasure! Yesterday used your fantastic Excel sheet in case of pipe! Thanks for this top!
And for your answer

My picture was that boundary layer will be scrapt from crank web surface by a sharp edge of duct...and this could be turbulent... clearance there is 1,2 mm there....

But on the other side if sharp as you and frits told... maybe the turbulence there could help the main part of duct flow surfing over the radius on web

Even when my picture is completely wrong...like just to understand what is happening in this scenario ...hungry for this

Grüße Wolfgang

[190mech]

Wos,
I am not a super tuner like a lot of this group, just a 2stroke nut so this might not be the best idea..
What about adding epoxy to the bottom of the intake duct to smooth out that stepped area allowing the mixture to flow smoothly into the crankcase??

[TZ350]

.


Happy to report that petrol in the carb bowl for the pilot jet and a separate methanol feed for the main jet idea works, or at least it appears so with an initial runup on the dyno.

Initial impressions. Idles and throttles Ok. Drank a surprising amount of petrol through the pilot jet. No stumbling when the throttle was quickly opened at any speed. Methanol fuel level stayed constant on heavy pulls. Power jet was suspiciously sluggish.

No dyno results yet, for some reason the PC has stopped talking to the Dyno electronics.

[Frits Overmars]

Power jet was suspiciously sluggish.

With 3/4 of the power jet supply line, including the control needle, above fuel level in the float bowl, the sluggishness cannot come as a surprise.
That Mikuni fitted their first power jet on top of the inlet tract 45 years ago does not mean we still have to do it that way.
Having said that, I love the way you use separate float bowls for separate fuels.