ESE's works engine tuner

[Haufen]

Frits have said no less than 1mm anywhere.

found it, thanks!

1 mm should be enough to avoid the viscous drag.

[F5 Dave]

Biased port timing, what's not to like?

Other than the nightmare seal issues...

Well the test ride seemed driveway slope assisted. Ok its easy to mock another's radical idea, its not like I could have come up with that let alone build it.

[Frits Overmars]

.. its not like I could have come up with that let alone build it.

I've had the idea in my head for over a decade but I never considered using a square-bore piston. I still don't ....
Before you ask: I just thought of the spherical piston/rod as a theoretical possibility. I would not dream of building it (well, maybe in a foul-stroke...)

[speedpro]

There is no requirement for any piston depth other than to make a connection to the rod and somewhere for a seal to be placed. Thinner the better really.

[Ocean1]

Ok its easy to mock another's radical idea, its not like I could have come up with that let alone build it.

I've had the idea in my head for over a decade

Don't you just hate it when other people have your ideas... first?

I didn't think of this, but it's very very cute.

[SwePatrick]

rocking piston would be a bad idea theese days when they are hunting emissions.

You´ll get a very odd burn when piston is tilting at top and squishband will alter around the piston.
And the fact it will be hard to balance it too.
all weight is 'wobbeling' none is constant reciprocating(spell?).

Rgds.

[2T Institute]

Helps if your cursed with French blood, but the tacho is in English to borrow Frits' phrase. seems to come on at 8, kick at 10, again at 12 and go through to 13, 200.

http://www.youtube.com/watch?v=OKqLZ...eature=related

[Frits Overmars]

...seems to... go through to 13,200.

If you're a motorcycle journalist that is sent on his way with 'safe' carburation, and to 14,500 if you are a GP-rider in a hurry.

[F5 Dave]

Stunning. Derbi know how to make a pretty bike,.

[wobbly]

Yea , the shift lights come on at 13200 just as it starts to get going - journalist safe as you say Frits.

[twotempi]

Probably a dumb question but ...........

Is the Derbi the same as an Aprilia RSA/W 125 ??

The bike had an Aprilia tacho dash unit.

[Frits Overmars]

The Aprilia RSW started in 1987 as a Rotax engine and evolved into a real Aprilia engine over the years. The RSA was designed by Jan Thiel and built in 2005-2006 at Derbi in Spain as the DRVE 125.
In the meantime Aprilia had gotten on the brink of bankruptcy because it had payed way to much money for the old Guzzi factory which turned out to be worthless,
a helmet-wearing law was passed in Italy which lead to a collapse of scooter sales, and all the profits (and then some) from the two-stroke racing department had been sunk into the four-stroke Cube project (the three cylinder GP-bike, designed by Cosworth).
Aprilias main creditor was Piaggio which already owned Gilera and Derbi. And when the Piaggio-accountants got control of Aprilia, they decreed to close two of the three racing departments and keep only the largest one (Aprilia) open. So the DRVE emigrated to Italy and was rebaptized RSA.
So from 2007 on, Aprilia, Gilera and Derbi GP-racers were identical except for their tank badges.

[F5 Dave]

. . . because it had payed way to much money for the old Guzzi factory which turned out to be worthless,
. . .

Like it didn't take a soothsayer to work that one out, Guzzi hadn't been a force since, what? the 60s? What were they thinking?

[2T Institute]

Yea , the shift lights come on at 13200 just as it starts to get going - journalist safe as you say Frits.

I always thought it was so when the journo told the team he hit the limiter here, here and there the mechanics could make universal 'wanker' gestures behind the journo's back .

[TZ350]

... changed the ports and skimmed the top of the cylinder to get the squish closer to 0.6mm. All this to take 0.35mm of the top of the barrel, we do go to some trouble to get the details right.

OK, after doing a lot of work getting the timing and squish right Thomas and I dynoed the 3ex cylinder up tonight.



And things didn't go so well.



Warmed it up OK and the first runs were knocking on 30hp then the power started dropping off. Re-checked the compression and it was only 120 psi hot where it was 150psi cold before the dyno session, so not looking good there.



Ignition curve is much tamer than before.

After going to so much trouble, it gets tiring having to re do things but I will get the cylinder of tomorrow and find out what went wrong.