ESE's works engine tuner

[Frits Overmars]

Attachment 357474
at first glance. Uncovering the exhaust ports at TDC does not look like it is the issue. But a more careful look may be warranted as the cylinder could be slightly rotated and that may expose an edge of an exhaust boost port.

I can't say for sure that your problems are caused by transfer short-circuiting, but it seems certain that you do have short-circuiting, unless you have used piston plugs.

[husaberg]

It would be pretty easy to say super glue some cork plugs as a trial to see if that is the major issue it only needs to last a few minutes soak the ends in an epoxy or similar, if they break off little harm done.

[F5 Dave]

Re Neels
I know nothing about website access issues but can he create a new account with a different email perhaps?

[husaberg]

Re Neels
I know nothing about website access issues but can he create a new account with a different email perhaps?

Use a proxy with a NZ location?

[wobbly]

I will suggest that to Neels.

TeeZee, if you find you do have Aux/A port linking, the way this was solved in the kart engines to enable running no plugs, was a full triangle shape on the Aux, such that only the very small top corner
radius of the Aux was in play, for only a very short time.
The top edge of the Aux can be much longer, utilizing the high Blowdown Pressure Ratio at APO
The other thing I see is the off the wall Aux shape dead in front of the A port - absolutely incurring short circuiting around BDC when the port depression is greatest .
I have used Hi Temp Ceramic paste in the Exhaust duct when testing the exit reduction idea, it never failed on the dyno - JB Weld make one.

[wobbly]

Neels very grumpy reply - " I cannot access the kiwibiker at all, not even as non-user. "

[TZ350]

The other thing I see is the off the wall Aux shape dead in front of the A port - absolutely incurring short circuiting around BDC when the port depression is greatest .
I have used Hi Temp Ceramic paste in the Exhaust duct when testing the exit reduction idea, it never failed on the dyno - JB Weld make one.

The exhaust duct tunnel was dug at the bottom of the axillary port because that brought it out between the cylinder fins. I will have to think about how I can change this.

[TZ350]

TeeZee, if you find you do have Aux/A port linking, the way this was solved in the kart engines to enable running no plugs, was a full triangle shape on the Aux, such that only the very small top corner radius of the Aux was in play, for only a very short time. The top edge of the Aux can be much longer, utilizing the high Blowdown Pressure Ratio at APO.

After doing lots of fancy difficult measurements trying to work it out. I figured the easiest and best way to check for port/cylinder rotation was to assemble it all up and draw a line across the piston at TDC.



Then disassemble it, pop the piston back in at TDC, align the pen marks and look inside.



Simple as, after wasting time doing it the hard way. A quick check and there is no exhaust or Ex axillary port exposed at TDC.

I can't say for sure that your problems are caused by transfer short-circuiting, but it seems certain that you do have short-circuiting, unless you have used piston plugs.

Piston pin plugs might be the next move. Last time I tried them they rattled loose and the transfer port shaved them away until they were just a ball of ally rattling around in the end of the piston pin.

[wobbly]

As I said you dont need pin hole bushes, a proper triangle Aux shape fixes both vertical and horizontal linking/short circuit issues.
More especially in your case due to having nothing like the RSA bmep, you dont need to even go close to bore center.

[TZ350]

I have used Hi Temp Ceramic paste in the Exhaust duct when testing the exit reduction idea, it never failed on the dyno - JB Weld make one.

I will see what I can find. I should be able to fill part of the auxiliary port to get a more triangular shape.

I have to say no more HP but with the auxiliary exhaust ports, over rev was greatly improved. It would run out past 10,000 rpm with ease.

[Wos]

The auxiliary seem to act very late after main exhaust opening !?
Most of the job seems to be done by main and its blowdown area

Maybe better to keep auxiliary small, away from transfers, away from center of bore and set them higher, let them only act in blowdown area

[jonny quest]

TZ350

Do you have capabilities for a wide band AFR? In real-time in dyno run?

When I originally replied I thought it was more of a short circuit thing between A and your odd shaped auxiliary ports.

You may see that with AFR.

If your carb needle is too rich, this will show up on dyno like this too.

What does bike sound like holding a steady state with slide in needle operating range? Does is blubber and not zing right through the RPM's?

Make a marker line on piston and show us the A transfer angle

[TZ350]

Piston pin plugs.

Reference cylinder.

TZ350 When I originally replied I thought it was more of a short circuit thing between A and your odd shaped auxiliary ports. Make a marker line on piston and show us the A transfer angle

Port discharge angles.



Alloy welding wire indicates placement of axillary port duct which is between the fins. My method to make the duct was to drill through between the fins. That initial drilling came out in the cylinder between the A and Ex ports. The upper part of the axillary port was cut into the wall of the cylinder with a mill. Speedpro handled the tricky milling job. I dug out the cylinder to connect the two parts, port and duct.

Yes. Quite a difference between the reference cylinder and mine in the area between the Exhaust port and A port. Might be a clue about where I am going wrong.

TZ350 Do you have capabilities for a wide band AFR? In real-time in dyno run?

Not now but I did use one and a data logging program with my 2Stroke EFI project.

[Hoebra]

wobbly, can you give me some advice about my PJ question from second last post on site 2740? Especially about the design of a PWM table in the ignitech? Thanks!

[wobbly]

Sorry I missed that PJ post completely.
Not the answer you want to hear, but the Mikuni solenoid PJ does not take kindly to PWM at all.
The tip wears , due to the constant hammering it gets from being cycled at 10Hz or so, and a " step " appears on the tapered end very quickly.
The Aprilia used a different solenoid for PWM, taken from a Fiat carburetor, that was originally an idle air control valve of some sort I believe ( and way cheaper as well ).

Anyway the PJ sizing depends upon the fuel used, for race or leaded gas where the overall jetting is run very lean ( simply because it can ) then the PJ size has to be quite small.
Using the Mikuni powerjets, this is in the range of 32 to 38 so that the amount of fuel being reduced is small, as the peak power EGT is already hot - well over 1200*C.
Unleaded or pump gas settings that are usually run richer with less compression and more advance, need approx twice the PJ size , up around 70 to 80.
This leans off the mixture alot more over the pipe, as its already inherently much richer.
These sizes are independent of the main used, and they work, even in a Lectron with no actual main jet at all.


As for the hard switch point, a good place to start is around 2/3 rpm between peak torque and peak power.
The fuel curve needs to start leaning of at this point due to the fact Scavenging and Trapping Efficiency start dropping immediately past peak torque, even though
the Delivery Ratio is still increasing.
But this effect is ameliorated alot by pulling out advance as the rpm rises, thus increasing the wave speed in the pipe.

Using PWM, the 0% point is closer to peak torque, and ramps to 100% ( ie no fuel ) somewhere again around 2/3 the way to peak power rpm.
Maybe Frits could confirm this, as I have never actually seen the RSW/RSA PWM table.