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