ESE's works engine tuner

[Gradella23]

Just get some raspberry juice, thongs and walk around for a bit....

https://www.youtube.com/watch?v=sKC2027ynMg

google FKM liquid. you will come up with products. Like below.
https://www.thermodynglobal.com/prod...ting-thp-2000/
Vitons a trade name. Like Vaseline

Thanks guys, i'll take a look.
This is what i'm working on: a 50cc Cagiva Prima racer.
This prototype reed valve is made to fit an Ibea 30mm carb on it, which has a 33,5mm exit diameter. It's a little bit large but i tried to arrange an acceptable internal duct.
This engine already has a nice inlet shape, and was born to also fit a 75cc so it has a 47mm large crankcase (bigger than a Minarelli or Derbi).
The cylinder base is with external studs so it's been possible to design a cylinder with proper transfer ducts.

[ken seeber]

Thanks guys, i'll take a look.
This is what i'm working on: a 50cc Cagiva Prima racer.
This prototype reed valve is made to fit an Ibea 30mm carb on it, which has a 33,5mm exit diameter. It's a little bit large but i tried to arrange an acceptable internal duct.
This engine already has a nice inlet shape, and was born to also fit a 75cc so it has a 47mm large crankcase (bigger than a Minarelli or Derbi).
The cylinder base is with external studs so it's been possible to design a cylinder with proper transfer ducts.

Being 3D printed, it might be possible that you don't need any coating at all, depending on the choice of filament. I was thinking of TPU, but not sure of its resistance to petrol.
However it sounds like you might know all of this. Another thought is that with a coarse Z height, say 0.28 (a Cura setting) that the voids in each layer, might offer some form of oil retention and subsequent dampening for the impact of closure of the reeds.
You can be our experiment. Looking forward to your durability test results tomorrow.:

[koenich]

I have a few PTFE CNC milled reed cages w/o FKM coating. I was worried at first but the reeds surprisingly last at least 15h racing in a 20HP 50cc before showing minimal signs of wear.

[wobbly]

I have printed around 30 reed inserts , the best have much more 1/2 moon rounded side fill volume than the one you show.
Here is an example with a thin divider added for a test.

[monkeyfumi]

I think he is looking at printing not just the stuffer, but the reed cage itself.

I'm not sure printed TPU would be stiff enough for a cage, PETG or Nylon would be a better material to try.

[skako]

Here is a calculation of the outgoing and return (reflected) waves acting on the opening port.
A return wave delay to the intake port can be seen.
I will try to put together a graphic for better understanding.


Here, after several hard days, I transferred the program. I put together a graphic where you can clearly see individual waves that are created during the process of "breathing" the engine.

[Gradella23]

Being 3D printed, it might be possible that you don't need any coating at all, depending on the choice of filament. I was thinking of TPU, but not sure of its resistance to petrol.
However it sounds like you might know all of this. Another thought is that with a coarse Z height, say 0.28 (a Cura setting) that the voids in each layer, might offer some form of oil retention and subsequent dampening for the impact of closure of the reeds.
You can be our experiment. Looking forward to your durability test results tomorrow.:

I'm investigating with my 3d printing expert colleagues to understand if there is something both fuel resisting and "soft" enough to avoid any additional coating.
the company where i'm working has an entire building of printers (they used to grant public money here for companies to invest in new tecnologies) so i'm trying to take advantage.. they also have a DMLS but unfortunately we can only print steel and titanium and no aluminium.

I have a few PTFE CNC milled reed cages w/o FKM coating. I was worried at first but the reeds surprisingly last at least 15h racing in a 20HP 50cc before showing minimal signs of wear.

this is nice to hear, i hope we'll reach the 20hp goal

I have printed around 30 reed inserts , the best have much more 1/2 moon rounded side fill volume than the one you show.
Here is an example with a thin divider added for a test.

thanks Wob, i have plenty of your works in my gallery. My cylinder is obviusly using a wobbly exhaust duct!
Regarding this reed cage, the problem is that is made to fit the Ibea 30mm carb (which i already have but i think it's too big for this duct) and that has a 33,5mm exit D.
To maintain a constant cross area i needed to enlarge the base section of the "insert" and i don't have any more room to create the 1/2 moon shape i was looking for (see pics). I guess the situation will improve a lot with the other carbs i plan to test (mikuni tmx30 and tm28ss).
The only way i have to reach that result with this setup is to squeeze the duct laterally but i don't know if it's worth...

[porttiming124]

Hello everyone.
A friend of mine set out to make a turbo methanol drag sled.
the original engine is a 2 cylinder 1000 cc
with a standard compression ratio of 12.5@1
the end goal would be to have about 15 lbs of boost.
Do any of you have experience with 2 stroke turbo methanol engines to line it up for starters?
compression, timing, air fuel, egt...
Thank you

[wobbly]

Just one more small detail re the stuffer to add. Even though Im dealing with a very small carb on a big reed ( 30mm/125 reed cage ) you would think that the carb bore was the limiting factor.
Not so , the best stuffers have a 2mm smaller venturi around 10mm into the block , where normally the area would be increasing or remaining equal.
This idea may work where your carb exit is " too big " ie neck the area down into a venturi within the stuffer.

[F5 Dave]

So it would go 30 at the carb slide, out to say 32 at the carb exit and back to 28 in the Reed? That is counter intuitive.

[wobbly]

Of course its counter intui it intuit , that big word.
Its a 2T , who would have thought making the Ex duct exit 75% would be WAY faster.
Or that too much Blowdown would wreak the scavenging due to LESS pressure at TPO.

[husaberg]

Two strokes were way more fun when we were just raising the ex port 2mm and cutting out 25mm of the belly...

[F5 Dave]

Look, I'm just going to keep my polishing mops primed up for max shine and be done with it yeah?

[husaberg]

The shorter old model straight rubber is best.
Here is a very old dyno test I did on a TM125MX motor we used to race in 125 National class karts, this was used with a VeeForce 2 and a bored SPJ powerjet carb..
Its a crap printout - used to be orange and red, but the short manifold looses no mid power, but is near 2 Hp up around peak.
The short rubber is obsolete and all but impossible to find.

https://italkit.com/epages/Italkit.s...ducts/TA.26.51
Not sure re the length it looks half way between

size is odd as well at 32mm and 36mm

[katinas]

So it would go 30 at the carb slide, out to say 32 at the carb exit and back to 28 in the Reed? That is counter intuitive.

Honda CR 125 2003 could hold the record for the biggest difference. For 2003 Honda made the biggest ever CR 125 reed cage ( 66 mm wide vs. 59 mm of 2002 ) with the smallest insert. Bigger air box, new carburetor 38 mm ( 36 mm 2002) huge reed cage and all this against 28 mm reed cage insert at narrowest point. Reports from testers:

"After a few hours riding the 2003 CR125R, we are happy to report that Honda has delivered a substantially improved motor, and that the chassis is just as sweet as last year. While last year’s bike required massive clutch abuse exiting corners, the ’03 model has a much broader, easier-to-use powerband. While “better breathing” might lead you to believe Honda produced a top end screamer with no low-to-mid power, this is not the case.

Indeed, the 2003 CR125R seems to pull harder from bottom to top when compared to the 2002 model (also available for our sampling at Carlsbad Raceway). For the first time in several years, Honda has a very competitive stock 125 motor to go along with its superb handling and suspension."

2004 same big 66 mm reed cage, but the insert dia. 38mm, same as carb .
From 2005 to the last 2007 CR 125, they return to narrower 59 mm reed cage with usual three petals and 38 mm insert.


Husa, other very short intake manifolds are used on the Yamaha YZ 125 from 2005 to 2022? Shorter could be to insert the carb directly to the plate that holds the reed cage.