ESE's works engine tuner

[Grumph]

That air cooled would have blown to pieces even on Methanol with that sort of com - insane.
I mentioned awhile ago a project I was doing for the Webco type RD series of heads, 250,350,400
The prototype has just been cut on the CNC, so I could be able to supply blanks, or a special design with precut toroidal chamber, quite soon.

I'd be interested in a blank when they become available.

[tdc211]

[/QUOTE]Wobbly

With the reverse stagger giving better transfer area ( as the B,C ports being high with alot of width compared to the previously high A port ) the engine now made 2 Hp or more than the factory trick cylinder
but was now 8 Hp up at 14000 and gained 400 rpm of usable overev, as previously it dropped dead at 13800 on track.
This setup proved to be quite insensitive to jetting and timing changes, allowing alot more static advance giving much better off corner power without killing revs as this would normally do.
Thus the enhanced blowdown flow of the radius at low port openings,allowed those much lower timings to be used effectively, enhancing power everywhere, but most importantly in the overev,where blowdown is most needed.

[QUOTE] Wobbly

Perfectly correct, Jan Thiels setup in the Aprilia engines does exactly that - open the B first.
The B is wider than the A as well, and the lower A port helps to reduce the direct short circuiting upwards into the Aux Ex ports.
This layout maximises the available transfer port STA and is great for peak power at high rpm levels.
The usual reverse stagger as seen in Honda T port engines, with the A port the highest, works better in the 3 port layout when you are looking for wider power bandwidth.
Best example would be the KZ2 kart engines, as with no power valve, and the need to be able to pull hard from around 9000 to 14000 + this layout gives better
bottom end and overev power, at the expense of outright peak.
I have dyno tested high B port KZ2 engines, and been just over 50 Hp at the sprocket, but no matter what I tried with pipe length and ignition advance I could never generate
enough power down at 9000.
So although the cylinder was very fast in outright terminal speed, it lost too much off every slower corner, fine as a qualifying engine but no good diving under someone entering
a corner - as it simply would not pull out hard enough when on the "wrong " line.



I would imagine port stagger completly depends if your valved and what port timings ,ign you have to work with?
Or do the higher A ports still give a better off the corner drive?

[wobbly]

The high A port setup works well with no powervalve as its inherent characteristic is to give a wider ( though lower peak ) powerband.
Same issue with the KZ2 straight line ignition, with not enough advance in the bottom end, and way too much in the overev, this is again offset by the high A port stagger arrangement.
This works in cylinders such as the 8 port aftermarket Banshee things with no powervalve as well - but for outright top end the reverse staggered low A port gives a big boost
if you are fixated on ( or want ) dyno peak numbers.
Having the A port high is hamstrung somewhat in that it limits what size you can go to with the Aux Ex ports, and of course it also increases short circuiting from the top of the A port
direct into the Aux, so as I said you choose what limitations you are up against and port accordingly.

[wobbly]

The high B port KZ2 engine won the Nationals here in 2013 and was insanely fast down the shute.
But this year I went thru all the testing again with the newest iteration of the TM - KZ10 .
This had the casting changed by the factory that allowed much bigger Aux Ex ports, and proved in the final analysis to generate more bottom end than I could drag out of the older engine, no matter what.
It won the title again this year, proving to be faster in outright power terms than the very best World Cup winning engines by SavTech from Europe, due in part to the extra
off corner response - also down to the perfect jetting combo on the day.
A super proud day for me and the team, making the pass for the lead at the end of the main straight with 3 to go after getting a way faster straight entry speed and carrying it in the draft.

[pete376403]

Wow indeed. (124.9 + 4.2) / 4.2 = a compression ratio of 30.7. Ever considered diesel fuel?

Two stroke? Isn't real (as opposed to calculated) CR only start from where the ex port closes? So the swept volume is going to be maybe half of the (bore x stroke) volume. So 15:1 sounds quite reasonable on meth, all my speedway bike motors (4stroke, but anyway) ran cr around that on meth

[lodgernz]

Has anybody successfully adapted a piston that had too big a gudgeon pin?
For example, using a piston with 14mm pin holes on a rod with a 12mm pin? Is a sleeve on each side of the piston a recipe for disaster?

[speedpro]

Has anybody successfully adapted a piston that had too big a gudgeon pin?
For example, using a piston with 14mm pin holes on a rod with a 12mm pin? Is a sleeve on each side of the piston a recipe for disaster?

Been there, done that. On a CB360 running GSXR1100 pistons. Ran for quite some time but resulted in obvious wear on the bushes.

[Sketchy_Racer]

For shits and giggles, here's a pic of the insert I was talking about, along with the new replacement. Only a slight change....

[Drew]

Two stroke? Isn't real (as opposed to calculated) CR only start from where the ex port closes? So the swept volume is going to be maybe half of the (bore x stroke) volume. So 15:1 sounds quite reasonable on meth, all my speedway bike motors (4stroke, but anyway) ran cr around that on meth

Someone please tell me if this is correct. I was under the impression that the exhaust chamber is primarily design to force mixture back into the combustion chamber through the exhaust port just as it closes.

Or do I have the very basics fucked up as well as the details?

[wobbly]

Just some basic facts for those who try and compare 2T with 4T tuning, then confuse everything by thinking you can mix and match effective with full stroke com.
Look at the point where an exhaust valve closes on a racing 4T, then calculate what the " effective " compression is.
You will find that using that formulae is about as useful as it is using the same idea in a 2T - ie not at all - even though the numbers are remarkably similar.
As most all " racing " 2Ts run in a very small range of Ex port closing timing numbers, the effective compression idea has no real useful purpose in my opinion.
No one uses effective com in the 4T racing community for a reason,there is no valid reason for doing so.
Full stroke compression is way easyer and quicker to calculate, and tons of empirical data has made the actual compression used for a particular fuel also very easy to hone in on.
15:1 full stroke compression is low for pump gas in a small bore 2T,and super low for any 2T motor running methanol, comparing that data to the effective or full stroke com in a 4T is totally irrelevant.

[wobbly]

Yea Drew ya got it 1/2 right.
There are 2 reasons for having a chamber.

1 - to suck the chrome off a tow ball when the piston approaches BDC.
2 - to pump mixture back in as the piston approaches EPC.

So as you are alluding to - with a heap of extra mixture being pushed into the combustion space as the piston rises, this totally invalidates ANY reason to
be using effective com as some sort of set in stone measure of a 2Ts performance characteristics.
The efficiency of the chamber and its interaction with the Ex port timing, throw up so many variables that no effective compression number can have any real meaning at all.
We finally found something you are good at - whew.

[F5 Dave]

Has anybody successfully adapted a piston that had too big a gudgeon pin?
For example, using a piston with 14mm pin holes on a rod with a 12mm pin? Is a sleeve on each side of the piston a recipe for disaster?

Someone in the very page helped me make some very nice sleeves to run YZ piston with MB rod, 16 vs 14. I won't name them as they were well made, although it was Sketchy. But yeah it didn't go well,twice. I don't know whether it was directly attributable to the sleeves. possibly it wasn't, and certainly not Sketches fault as I told him what to make, but it has made me shy of doing it again. Next time I'd rebuild the crank with another rod to suit the piston. I cheaped out of doing it for the cost & the boring of the crank required. But choosing the best piston is the foundation of a good engine.

[peewee]

The high B port KZ2 engine won the Nationals here in 2013 and was insanely fast down the shute.
But this year I went thru all the testing again with the newest iteration of the TM - KZ10 .
This had the casting changed by the factory that allowed much bigger Aux Ex ports, and proved in the final analysis to generate more bottom end than I could drag out of the older engine, no matter what.
It won the title again this year, proving to be faster in outright power terms than the very best World Cup winning engines by SavTech from Europe, due in part to the extra
off corner response - also down to the perfect jetting combo on the day.
A super proud day for me and the team, making the pass for the lead at the end of the main straight with 3 to go after getting a way faster straight entry speed and carrying it in the draft.

you have the C same height as B ?

[wobbly]

In the high B port engine yes.
In the high A port, the B is lower, the C lower again.

[peewee]

well maybe im fuked. the honda cylinder i have was 124 A and B. 127 C. so i put A at 128 and B/C 127. ill try it and see. if that dont work i can put B/C at 130 and leave A at 128 and try that

my concearn is not letting the transfers get to high but i think ill be ok