ESE's works engine tuner

[ceci]

These two cylinders freshly cast, destained for the 700cc track bike.

I feel disappointed, I thought that in this new engine I would try some new solutions that can increase power.
It is very frustrating for those who do not have the means and cannot do anything, to see how those who can do it do not do it.
There are already many 700cc two-cylinder motorcycles "with KTM cylinder and others", there are even those with CR500 cylinder, but none of them have anything new. And less when it comes to power increase.
I hope you understand me and don't be offended

[Javier Ruda]

if the transfer ports and the blowdown are not granted, there is no point in enlarging the admission.

for admission, I am inspired by the kart rotax max cylinder.

I have tried to copy Rotax Max admission:


--- Crankcase before ---



--- Crankcase after ---



--- Cylinder underside ---



--- Boyesen ports before (right) and after (left) ---



I copied this because I like Rotax Max power curve, with peak at 12000 rpm, and I guess that this intake type can be beneficial, but I am not sure at all.

Does anybody knows the phisycs behind this evolution on the Rotax engines?

[Flettner]

I feel disappointed, I thought that in this new engine I would try some new solutions that can increase power.
It is very frustrating for those who do not have the means and cannot do anything, to see how those who can do it do not do it.
There are already many 700cc two-cylinder motorcycles "with KTM cylinder and others", there are even those with CR500 cylinder, but none of them have anything new. And less when it comes to power increase.
I hope you understand me and don't be offended

You will note the cylinders have the quad injector lugs.
Its not the only engine Im building.

[TZ350]

.
More from 2Stroke Stuffing:- https://youtu.be/7Dk9nYfO7Wc a change of direction.

Rotary exhaust valve was great for a wide spread of power but now looking for peak power using supercharger and expansion chambers.

[ceci]

You will note the cylinders have the quad injector lugs.
Its not the only engine Im building.

Flettner, you know what I mean, to supercharge the cylinders, in the way that I indicate wobbly, of which I made a suggestion to be with separate pipes and with operation control.
I do not think it is incompatible with the use of the TPI mk2 system, on the contrary I think it would improve reducing the loss of HC

[wobbly]

My opinion would be that its near on impossible for someone like Flettner to spend his working life learning to be an expert in CNC machining , metal casting / pattern making to enable him to
run a business making money building aero gearboxes and gyro aircraft - and on top of this effort to become an expert in the latest two stroke technology such as using EngMod and designing pipes etc.
I can manipulate 2T data and do the CAD work to build anything using 3D laser technology , he cant , simply as there isnt sufficient time in each day , but then I have no clue when it comes to foundry skills .

He does the two stroke thing as much as a hobby interest as it is a commercial enterprise , and I would love to be able to learn his skills - but then its taken me a lifetime of learning how to
make a living out of the small part Neil cant do.

[Flettner]

My twostroke endeavors are just a hobby, like most everyone else here. Although it can get quite engaging sometimes.

[TZ350]

Tupper Ware lunch box. All in one, carb cover and catch tank.

Second try at protecting the carb from wind blowing across the bell mouth and upsetting the mixture.

[pete376403]

Tupper Ware lunch box. All in one, carb cover and catch tank.

Second try at protecting the carb from wind blowing across the bell mouth and upsetting the mixture.

With the hole pointing forward you will get a ram effect, theoretically raising the air pressure above atmospheric depending on speed. How you going to jet for that? Would it not offer a more consistent air flow with the hole pointing to the back?

[F5 Dave]

I'm still a bit hungry. What was in that before? If it doesn't work, can you still claim a replacement on that famous Tupperware warranty?

Or for shame - have you cheaped out on an inferior copy?

[wobbly]

Ram effect , has no useful effect at all till well over 100Km/Hr.
And GP/Moto bikes had/have long , small area intake tubes connected to large volume air boxes that form proper Helmholtz tuned systems.
Robs plastic thingy may help prevent carb standoff being affected , and keep rocks out , thats about all he wanted I believe.

[ceci]

Flettner, you know what I mean, to supercharge the cylinders, in the way that I indicate wobbly, of which I made a suggestion to be with separate pipes and with operation control.
I do not think it is incompatible with the use of the TPI mk2 system, on the contrary I think it would improve reducing the loss of HC

This way of supercharging I mean

And adding to the effect of having very high exhaust duration you can cut the skirts short such that the port is open a few mm when the piston is at TDC.
Wreaks havoc with the jetting , but in the project i tried that we were using big pumper carbs.
Very easy to adjust the fuel curve as was needed - but I doubt a normal carb could be made to work.
This setup on a " stock " 950 SeaDoo gave an added 8 Hp in about 80 , so 10% - enough for the title at Havasu.
On a 1180 twin race motor the bump was 15 Hp in 120 so a little less.

That fact intrigues me, filling (supercharging) supplement volume charge for the exhaust why it happens.
How to get that little supplement volume of cargo to the exhaust:
The depression of the main exhaust creates a venturi effect and attracts it
the inertia of the incoming mixture forces it out through this small slot.
Which of the two causes can it be?

I believe it's the split suction wave from the single diffuser that find it's way into the tdc side crank case. Or it's explained on previous pages.

If you mean the video of the 3D figures, if I did it, if what you mean if I have done something like that with a real engine, NO, doing it is not within my reach.
The bottom line is: can cross feed work on engine twins?

As I said i'm not excactly sure why that engine made more power. And also as I said, I think it had a shared pipe with a y- section to the cylinders, so there is no need to have ducts from one cylinder to the other. If your idea works with separate pipes, I don't know.

Not trying to test this solution makes me suspect two things:
Not enough hp increase to create motivation.
Not confident it will work (for separate pipes)

[husaberg]

With the hole pointing forward you will get a ram effect, theoretically raising the air pressure above atmospheric depending on speed. How you going to jet for that? Would it not offer a more consistent air flow with the hole pointing to the back?

on a bucket it will not increase your speed to any great effect but it will f up your jetting to a great effect.
stuff to follow.

[Frits Overmars]

With the hole pointing forward you will get a ram effect, theoretically raising the air pressure above atmospheric depending on speed. How you going to jet for that? Would it not offer a more consistent air flow with the hole pointing to the back?

Not necessarily; with the backward hole a speed-dependent underpressure could develop behind the airbox which could just as well mess up the jetting, the difference being that the mixture would then become too rich instead of too lean. The piston will like it but you won't win races that way.
I'd rather have a mixture that is too rich at low speeds and perfect at high speeds, when you need full power because of the air resistance.
Fletto, I'll save you the trouble of reacting: with fuel injection we can have the best of both worlds.

Robs plastic thingy may help prevent carb standoff being affected and keep rocks out.

Keeping rocks out seems like a good idea, a very good idea.
An airbox will definitely affect standoff. If there is standoff at all, in the absence of an airbox it gets blown away before the engine can inhale it.
An engine with an airbox will re-inhale this standoff that already carries its portion of fuel, messing up the carburation.
This leaves us with two options: omit the airbox or ensure that there is no standoff. I know which option I prefer.

[wobbly]

I think the important take away from that article is the statement that with 135 bhp available , the ram air system at 120mph had 20mB of " boost " and this gave " the odd Hp ".
ie at 120mph is doing F all , and thus wont be affecting the jetting required.
Convert that to bucket power and speed numbers on track , cant see it being an issue.