ESE's works engine tuner

[SS90]

Ermmm,

Would you believe polished the ports and raised the primary compression?

Lets forget about my "scoota" tho, your problem is more interesting....!!!!

[TZ350]

Yea, I have to admit I felt silly even suggesting "raise the primary compression", as it is the battle cry of the "I can tune a two stroke, but don't know jack squat" guys,


How many times has some guy asked you...

"That's fast mate....did you polish the ports and raise the primary compression?"

"ermmmm..... no"

"oh, you should do that, it would really go then!"

But by what I see from your results so far, there needs to be an alternative solution to this problem, and possibly, in this case it would help.

Yes I think so too, thanks. Will put it on my to do list. I had wanted to improve the internal air flow, now I know I can without over compressing the crankcase.



What have you done with your SS90?

Ermmm,

Would you believe polished the ports and raised the primary compression?

Ooooo the irony, that's pretty funny.

I see you have your scooter with a good looking pipe up on a dyno, how did that work out?

We have tried an on-bike dyno system that used the change in spark frequency to calculate the rate of acceleration and graph HP and Torque from the mass/acceleration relationship.

The idea was to use a tape recorder to pickup the ignition noise. Then down load it to a computer through the sound card. Clean it up, enter some basic data like gear ratio's weight etc., then the software graphed it all.

It worked with the car but just could not get it to work on the bike. It just would not pickup a clean signal that the software could recognise.

I think the problem was that the amplitude of the bikes ignition varied so much with the applied load. The peak to peak levels were much more consistent with the cars ignition.

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[speedpro]

I'm well familiar with gas flow and why it does. I own a home made turbo Z1 that makes a bit of power, I've crewed on a top door slammer blown drag race car that also made a bit of power, my buckets have all been reasonably competitive.

The critical factor with crankcase volumes in a 2-stroke is that there is enough volume to not stifle flow before the transfers close when the motor is operating at maximum. Obviously having excessively large volumes beyond that which is "required" will be detrimental at all other times. Hence a typical 2-stroke compromise is required. I do agree that the primary compression "aids" transfer, but, once the motor is operating at max the volume becomes the critical parameter and it may be greater than what is ideal off-peak. We are discussing a race motor so aren't particularly worried about off-peak, except in the usual 2-stroke tuning way - it has to be rideable.
I've spent a few hours pissing round on dynos testing this sort of thing plus more recently i spent a few $$ getting the Wobbly treatment and words of wisdom. He's pretty hard to disagree with I reckon. Results talk as well and I'm happy to do comparisons on a dyno.

[bucketracer]

I don't think of an engine as just a pump, particularly not a 2 stroke with an expansion chamber. For 2 reasons. Let's see if we can all name them (and that's is disregarding the whole thermodynamic side of an engine).

Ill chance my arm here.

Resonance in the inlet tract/crankcase.

Resonance in the expansion chamber.

Either of which and especialy if they are working together achieve more mass flow than the pumping action of the motor could by itself.

Do I get a Chocolate Fish?

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[Buckets4Me]

no choclate fish for you
it's a 2 stroke so as well as pumping air
the engine


makes NOISE
and SMOKE

[bucketracer]

The crankcase volume has very little to do with getting the mixture from under the piston to on top of the piston. The pressure differential across the transfer ports at the moment they open at operating speeds is mostly due to tuning specs - pipe/ex port. Gas velocity, and therefore inertia, in the ports also contributes and what is trapped/returned to the cylinder after the transfers close is due to the pipe design again and the port. The crankcases are more or less just somewhere to store air/fuel mix until it's sucked up the transfers.

I can see what is going on here. The pumping effect gets the motor going but when its up on the pipe. The mass flow through the motor has a lot more to do with the resonant effect of the inlet-tract/crankcase and expansion chamber and the pumping effect just calls time like the cox does in a rowing six.

Those waves are tough little sods, shifting all that air/fuel mass.

And they can get a lot done when they work in unison.

[Buckets4Me]

[Ned Kelly]

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Good on you SS90. Great to see someone giving Speedpro and F5 Dave the learn. What would TeeZeethreefiddy know he's just a grey haired geriatric old fart, only finshed third in the last Bucket GP at Taupo, how pathetic is that, third!! I ask you.

Can't be to hard on him I suppose, He did finish, others didn't. Some of them were good guns too. Can't blame them 45min or so full tit around Taupo might be a bit hard on a buckets reliability.

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[speedpro]

The Air Force GP tracks were bigger and faster. My bucket has been round Pukekohe at a couple of meetings with no problems which is probably one of the bigger tests available now for a bucket. I've won the odd meeting and championship all on buckets I built and tuned. F5 even more, even if I had taken him out earlier in the day. As for the "learn", I think TZ could probably run rings round all of us but as is usual with learned(lur ned) ones he sometimes gets distracted by a good theory.
Oh yeah - a bucket of mine completed the 6-hour still going strong and in good condition, unlike the owner.

[TZ350]

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Taupo....Fortune smiled for me on the day.

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[xwhatsit]

Coolest thread on KB!

Keep going with the 2T lessons!

[TZ350]

As for the "learn", I think TZ could probably run rings round all of us but as is usual with learned(lur ned) ones he sometimes gets distracted by a good theory.

Don't you just love a good theory I do.

Yep. I have found that the problem with a good theory is that, its Ohoo so easy to also believe its true.

And then reality, pays a visit ..... goodby theory!!

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[SS90]

Don't you just love a good theory I do.

Yep. I have found that the problem with a good theory is that, its Ohoo so easy to also believe its true.

And then reality, pays a visit ..... goodby theory!!

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Guys, Prepare to learn that 1) Nz is a cool place, and I love it but .....A) NZ IS NOT THE CENTRE OF TWO STROKE DEVELOPMENT..... AND B).....

I don't want to turn this into a BLOG, but I am a Kiwi, (born in the North, raised in the South...Son of an Ohakea Air force guy (and girl)....)) I now live in Germany (Baveria to be precise), And earn my living from developing .......................

AIR COOLED, TWO STROKE 125 (AND 140) CC CYLINDERS......................




See the pics attached..

If you don't believe me, does your keyboard have these characters.............


ä......ö......ü......, or the best one (the give away...ß )...........
Anyway....... I am not trying to be a "know all", but I have ALOT of experience with this subject matter, and am willing to pass it on to.....

"the boys back home"

Two years ago, I developed a cylinder (air cooled, cast iron lined, aluminium skinned cylinder for small fame Vespa's)

....When I say "developed", I mean I was given a plagerised pieced of scrap, that was just that.....scrap.....

However..this piece of scrap managed 15 P.S , and 15 N.M on the Dyno....

And, the port timing was A) stolen from another cylinder designed to fit tuned small frame Vespa's, and B) 10 years old.


So, 2 years ago, I set about making it better


Developing it.......

I started with 15 P.S, and, when I started (with only the exhaust port timing which was much too low, as was the transfer.... THEN I LEARNED THAT EVERYTHING WAS WRONG.....)

.... And, also the transfer design had a problem, (PARTICULARLY THE TRNSFER SCAVENGING) as it was stolen from another company, who specialises in Vespa scooters....... It's called C.V.F.... (DESIGNED BY MALLOSSI)......and if you don't know what C.V.F is, and...... consider yourself an "EXPERT" .......(x being a factor of Y, and spurt being something that comes out the end of your man servent)

Then you are 10 years behind Two stroke development.........


I digress......

This Cylinder is an Aluminiun skinned cast iron lined cylider, with piston wíndow induction (via reed valve....much like an RZ250/350)


I started with 15 P.S, and after the first "attack" with the Dremel (die grinder, along with a degree wheel and a Dial test indicator)... I ended up with 19 Ps and 15 odd NM..... but it was too peaky......

The Pipe I was using was called "Franz", and develped by a guy called Mataus Shierer, who started with a pipe developed by Norrie Kerr (an English guy, who wrote a book called "TUNING VESPA'S THE NORRIE KERR WAY"..... I suggest you all read it..... It's still relevent.....especially when you consider a small frame Vespa is.......

" AN AIR COOLED DISC VALVED 125 (OR 50,OR 90) CC TWO STROKE"

Anyway, the "Franz" was (and is) a really good pipe....(by the way, it's named after the designers son, Franz...(pronounced Frantz).... the problem was (is) if you subject it to full throttle for prolonged periods, it has too lower volume in the chamber, and after sustained periods, it causes the combustion chamber to overheat....which in turn passes the heat on to the cylinder, which then expands at a rate that the materials cannot handle, which means that it expands too much....which means that the studs compress the cylinder too much......

So, yea, I know what I am talking about when it comes to cylinder studs compressing the cylinder............

The studs that a vespa uses are origonally 7 mm all the way through the shank........, and if you make them 8 mm , (like I did)... then the cylinder runs hotter, because it's "squashed"...going back to 7mm studs fixed this problem............

There is heaps of information of the "wasted" stud theory......

BY THE WAY, THE ORIGONAL AIR COOLED ENGINE FOR THE BRITTEN ENGINE (THE ONE BUILT AND DESIGNED BY BRIAN DENSON OF DENCO ENGINEERING ENDED UP HAVING WASTEN STUDS BECAUSE OF EXACTLY THE SAME PROBLEM...)

If you don't believe me, then read the book......

"John Britten, one man and his Dream", By Tim Hanna.....

So, back to my job.....

I played around all year with this thing (two years ago), and ended up trashing the whole C.V.F theory, as, because A) the cylinder skirt was too short to have an effect (in this situation)

and B) the application of FOREFRONT TWO STROKE DESIGN THEORY negated the nessesary weakening of the piston (and cylinder) that was required for the C.V.F system

Man, you guys are way behind....


And it is also copywrited....... "DOH"........

But, it didn't matter....because with a short short spiggot, the C.V.F system is (in my opinion...and over 250 runs on this cylinder 2 years ago has proved) is of little (actually none whatsoever) effect......

Can any one tell me A) Why, and B) how you can achieve a better result that C.V.F...with out weakening the piston (or cylinder wall ))


The pictures I have shown include the C.V.F system.......... (Which, as I say, is stolen...but the pictures of the Cylinder are the same ones that make Over 20 P.S (as are the Dyno graph pics).....

Oh, yea, the Pic that shows 28 P.S (WHICH DOES NOT HAVE THE C.V.S SYSTEM...AS I FOUND AN ALTERNATIVE TO THE C.V.F METHOD OF IMPROVING THE UNDER PISTON SCAVENGING AT B.D.C........is the most I have ever seen out of an............

AIR COOLED, DISC VALVED 125cc TWO STROKE....


Also, I know alot about "DISC VALVED, 130CC TWO STROKES RUNNNING 24MM CARBS.."

As, that is the day to day business of any Small Frame Vespa Tuning shop in Europe....Because Polini make the most reliable "Jeden Tag Roller " (Every Day Scooter) tuning cylinder available....


Now, This is (The Polini Cylinder, not the one I have developed, which is an ally skinned cylinder with a cast iron liner......like a GP 125, aye...Although, We now have either a 125, or 140cc option....) a CAST IRON cylinder, and, it needs a VERY long inlet manifold(because of the design of the small frame Vespa requiring it to be that long) (which is included in the kit, to which ONLY A DELLORTO PHBH24 (That's right.... a 24mm carb........) will fit.... (other than extensive mods....which are expensive to say the least)

Oh, the 28 P.S is with my own exhaust as well.....

And.... the cylinder head HAS NO SQUISH BAND............ Does that blow ya mind..........

The reason I did that was to keep "THINGS COOL".....

And..... The Primary compression ratio is 1.49:1

I have loads of dyno runs experimenting with primary compression ratios......

1.5:1 is always the best curve (long and fat)....

Oh Yea baby........

LONG AND THING MIGHT GO STRAIGHT IN,

BUT LONG AND FAT IS WHERE IT'S AT!....



I just finished designing an ignition system too.........

It was easier than the Cylinder.........

It only took from November last year untill the 20th of Fen this year.....

It retards 10 DEG from idle (at 9000 RPM), which test have shown is ideal for

AN AIR COOLED DISC VALVED...


YOU GET THE IDEA......



I Know what I am talking about.....

Oh, yea, If anyone tries to tell me that the transfers are too small (from the pictures), then they are right, they are only 10% bigger than the pics to give the results in the graph.....makes you think about transfer port area .....AYE
Boys..........

Happy Hunting.....

Try not to hit the key board when you aim for the screen.................. aye guys!!!!!!!!!!!!!!!!

[bucketracer]

Honestly SS90 you look like you could contribute some interesting/usefull info that we would all like to read and benifit from but your attitude is getting in the way. Lose the imature "Need to be Right" chip on your shoulder and then we can be friends otherwise bugger off and be an "EXPERT" (as you define it) some where else.

So whats it to be

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[TZ350]

Hi SS90

Impressive stats. I have Googled "TUNING VESPA'S THE NORRIE KERR WAY" looks an interesting source.

I have been looking at your barrel pic. I need your help in understanding it.

This is what I see:- inlet looks like it has two boost ports above it, the exhaust port width looks in the low 65% of bore diameter, not much port time area there, a bridge port is said to flow less than a single port of the same area and I don't understand the extra ports below the transfers.

I need your help in understanding how this barrel makes 28Ps. please could you enlighten me with a few pic's and diagrams (hand drawn's ok).

Your work place sounds interesting, how about a few pics of the man himself at work.

There are pics of us at work on the GP at the begining of this thread.

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