ESE's works engine tuner

[lodgernz]

Thanks Dave, I do consider a modern ignition, gonna look in the link.

This is not cheap, but should be a big improvement.
https://www.hpi.be/item.php?item=210K176

[Tim Knopper]

I just wasted a couple of hours trying to keep up with all the rubbish that is written in a Facebook group called "2 Stroke research & development".
[/QUOTE]

Very strange reaction of Master Jan on Wobbly

[jamathi]

I just wasted a couple of hours trying to keep up with all the rubbish that is written in a Facebook group called "2 Stroke research & development".

Very strange reaction of Master Jan on Wobbly[/QUOTE

There is no reaction of mine on Wobbly at all!
All the contrary, I respect and admire him....
And I think he is the best 2-stroke tuner in the world at the moment!!!

[dutchpower]

Tim

Jan has a special way of humour if you understands his humour you know beter

[jamathi]

Tim

Jan has a special way of humour if you understands his humour you know beter

I REALLY mean what I say!!!

[andreas]

This is not cheap, but should be a big improvement.
https://www.hpi.be/item.php?item=210K176

Perhaps. The ignitech seems like a good option though.

[andreas]

I just wasted a couple of hours trying to keep up with all the rubbish that is written in a Facebook group called "2 Stroke research & development".

Very strange reaction of Master Jan on Wobbly[/QUOTE]

Now where is that Rabbit?

[peewee]

I was meant to post this ages ago i think i described the construction only at the time.
Notice the oval to round transition
This is one piece but would be pretty easy to fabricate out of a thick wall pipe and flange. Pipe turned down on outside afterwards.
Attachment 339993Attachment 339994Attachment 339992Attachment 339997
4 spring holes
3 turtle doves
two locating dowels
and two o-rings for belts and braces safety.

yes i plan to make the spigot like you describe. it will be fully round where at exit. four hold down springs, two at top and two at bottom. it will bolt on the cylinder with only sealer and no gasket as this method has worked good for me before. not sure yet if ill use steel or aluminum

[katinas]

[QUOTE=Frits Overmars;1131119962]No problems with big end lubrication Katinas?


[ATTACH=CONFIG]339990

Before first road tests I worry about this, but looks like reality is opposite. Every time when I take off cylinder, crank was much more oiled than usual with std. Maybe isolated crankcase space, when piston is at BDC, holds oil around crank ( with autolube, directly to crankcase would be really good). All summer tests was without any big end troubles.

From gas dynamic side with this configuration, I cant really understand whats going on in transfers ports and crankcase space, just try to imagine.

Tried every possible combination of holes in the piston (add pic piston with 210 and 245 duration), but power always was worse. So I try to eliminate all holes with block plates, screwed to the piston inside with bolts. I am lucky that one of the bolts broke just, when most tests was done with this piston.

[Frits Overmars]

Having gathered that a constant radius and a tapering port area are desirable I've been working with two offset circles to define a shape that meets this. So far I've been sizing the rest of it to give the desired entrance to exit area ratio. But depending on the length of the port this can result in a wide range in the taper.
So, is there an ideal taper that should drive the design? Or is the area ratio more important? Or is it a balance where both are important? Or does the smaller radius needs more taper to keep the flow attached?
To illustrate the point I've drawn two "ports" with the same area ratio but vastly different taper.
Attachment 339998

In addition to your drawing there is another factor to be considered: the axial exit angle. Together with the requirement of the largest possible inner radius that will fit between crankcase and transfer window, your choices are already fairly restricted. The geometry of the RSA A-duct, below, may illustrate what I mean.
If you google Helmholtz, you will find an explanation involving a volume and a cilindrical duct. A conical duct like a transfer duct makes things a bit more complicated.
Port length + taper comes down to the same thing as port length + area ratio. They offer me the opportunity to create a conical duct with the Helmholtz property that will work at a desired frequency in combination with a given crankcase volume and port timing.

[husaberg]

yes i plan to make the spigot like you describe. it will be fully round where at exit. four hold down springs, two at top and two at bottom. it will bolt on the cylinder with only sealer and no gasket as this method has worked good for me before. not sure yet if ill use steel or aluminum

The two orings are for the pipe sealing rather than Cylinder to spigot (lower 50mm in pic)

the locating dowels were a nice touch as well, bottom of pic about the size of needle rollers)



These pics of a Riley Will Spigot better illustrate the cutouts that merge the Aux ex ports.


The turtledoves are optional
I have a suspicion there is a ceramic coating on thre inner walls of the spigot of the DEA one
There is a pic in the Frits files of a Gen Aprilia one on a Cylinder (Flet has my dea one ATM)
Here is what i believe was the progression of the design from Rotax RSV to RSA

The bottom ones are BRC Riley Will but i think they follow the late Aprilia pattern
Interestingly the multiple overlapping spigot is how i did mine back in the day only i just used different pipe and only one lathe cut and the flanges were cut with handtools
Maybe Frits or Jan can correct any of the progression i got wrong

[peewee]

frits to have any chance of sucess, the facebook group has to be private. other wise every idiot on the planet is making comments of bullshit

[Frits Overmars]

frits to have any chance of sucess, the facebook group has to be private. other wise every idiot on the planet is making comments of bullshit

As far as I'm concerned, Facebook simply is not the right medium for any in-depth exchange of ideas. Forums are far more suitable for that kind of thing.
Kiwibiker is not a private medium either, but at least here we can have quoting, a timeline that does not get cluttered up three times a day, and some social control.

[OopsClunkThud]

In addition to your drawing there is another factor to be considered: the axial exit angle. Together with the requirement of the largest possible inner radius that will fit between crankcase and transfer window, your choices are already fairly restricted. The geometry of the RSA A-duct, below, may illustrate what I mean.
If you google Helmholtz, you will find an explanation involving a volume and a cilindrical duct. A conical duct like a transfer duct makes things a bit more complicated.
Port length + taper comes down to the same thing as port length + area ratio. They offer me the opportunity to create a conical duct with the Helmholtz property that will work at a desired frequency in combination with a given crankcase volume and port timing.

Thanks!

As a followup, how important is the smoothness of the rate of change in the duct cross section? seems like that would be important, but how to control for that condition is not obvious. If it is important, and we are constrained to the inner radius being constant, then an equiangular spiral could be used for the outer surface. In this example the outer surface has a constant 8° angle to the inner radius.

Is it worth the trouble?

[Frits Overmars]

As a followup, how important is the smoothness of the rate of change in the duct cross section? seems like that would be important, but how to control for that condition is not obvious. If it is important, and we are constrained to the inner radius being constant, then an equiangular spiral could be used for the outer surface. In this example the outer surface has a constant 8° angle to the inner radius. Is it worth the trouble?

Smoothness is important. Any irregularity can be seen as a very small, abrupt radius, causing turbulence and loss of pressure.
We are not constrained to the inner radius being constant, but in order to avoid flow detachment, the inner radius should increase as the flow velocity increases along the duct. Or to phrase it another way: the inner radius should increase as the duct's cross flow section decreases.
Decades ago I came to the conclusion that the optimal duct shape could be described with two e-curves. Some decades later I came to the conclusion that it wasn't worth the trouble .