flat slide vs round

[Nathan S]

The reason he loves Dellortos is that he has a pallet of Dellorto needles & seats that he needs to use up .... before lunchtime.

[Lozza]

The reason he loves Dellortos is that he has a pallet of Dellorto needles & seats that he needs to use up .... before lunchtime.

 
Everything must go..........Lozza's gone madder sale..........my birthday but you get the presents..................

What would make you run one of the Dellortos in place of a Keihin PWK Airstriker on a big bore 2 stroke?

tunability of a Keihin is not in the same league as a Dellorto 

[Slakewell]

I love Bings, Yes they are harder to get right and Yes when they wear there not good. The good bits nothing makes as much power as a Bing and the throttle is light easy action.

[sa63]

Never tried A dellofto on a 2 stroke, but its the way To go on a 4 stroke for sure

[davidmc]

Dellorto on 2 strokes make power, as do Bings!

[Momus]

The reason he loves Dellortos is that he has a pallet of Dellorto needles & seats that he needs to use up .... before lunchtime.

LOL.

On the 2 Strokes Downunder 380 KTM/Cagiva project Lozza is singing the praises of a power jet modified PWK.

[Lozza]

That was a long while a ago and thinking of swapping to a VHSB, plus I had several PWK's lying around  Keihin are good, mikuni  better , Dellorto much much better.

[John Orchard]

I cannot see how one carb can make more power than another, sure one may have better component supplies but they all have similar circuits .... pilot jet, pilot air bleed, slide cutaway, needle, main jet, main air jet.  Sure flat slides increase pulse strength at part throttle but they would ALL flow the same at WFO ..... I think you guys are jerking us off  ;-)

[Tim754]

John think    real MiKuni   vs  Chinese copy muckuni   looky same....but no goee same  not even a wide FkN open.

[Lozza]

I cannot see how one carb can make more power than another, sure one may have better component supplies but they all have similar circuits .... pilot jet, pilot air bleed, slide cutaway, needle, main jet, main air jet.  Sure flat slides increase pulse strength at part throttle but they would ALL flow the same at WFO ..... I think you guys are jerking us off  ;-)

Not really Mikuni and Keihin are tuned with the main jet ,Dellorto's(maybe Bings ) and Lectrons are tuned via the needle not so much the main jet. A VHSB dellorto has a pilot to needle transition jet/ atomiser and a needle to main jet transition jet and atomiser

[Momus]

I don't doubt the Dellorto is an effective carby, but gee, weight of numbers OE and aftermarket and anecdotal reports give the PWK, PWK Air Striker high marks.

From Google sourced images of Dellorto VHSB34's the internal layout of the carb shows Mikuni/Keihin similar pilot and main circuits with air bleeds/ emulsifier holes on the pilot and main circuit brass ware. I cannot see any obvious design differences to the Jap units.

The Dellorto's slide guide arrangement looks like a conversion of a round type rather than the more sophisticated, to my eye a least, dedicated Keihin design.

[John Orchard]

I guess it doesn't really matter whether the needle or the main jet is metering fuel at a given opening, as long as the air/fuel ratio is correct at any slide opening/rpm.

Having air bleeds ensures the chance of correcting the fuel curve for all rpm's, so, if a given bore size venturi is giving the selected air/fuel at all of its adjustable areas, then they must all make the same power?

[Lozza]

I don't doubt the Dellorto is an effective carby, but gee, weight of numbers OE and aftermarket and anecdotal reports give the PWK, PWK Air Striker high marks.

From Google sourced images of Dellorto VHSB34's the internal layout of the carb shows Mikuni/Keihin similar pilot and main circuits with air bleeds/ emulsifier holes on the pilot and main circuit brass ware. I cannot see any obvious design differences to the Jap units.

The Dellorto's slide guide arrangement looks like a conversion of a round type rather than the more sophisticated, to my eye a least, dedicated Keihin design.

All those Guzzi's Ducati's Aprillia's Cagiva's and a long line of scooters don't count? Dellorto is a needle carburetor not a main jet depending on set up normaly with a Dellorto the main jet only becomes dominant at around 90% throttle. There is the difference. Just have learn how to use that to your advantage.

[Momus]

All those Guzzi's Ducati's Aprillia's Cagiva's and a long line of scooters don't count? Dellorto is a needle carburetor not a main jet depending on set up normaly with a Dellorto the main jet only becomes dominant at around 90% throttle. There is the difference. Just have learn how to use that to your advantage.

I found a decent scale parts diagram in english which was helpful; it showed the separate air bleed and emulsion parts of the pilot and main circuit. I can imagine that the variable, by replacement, main jet 'atomiser' secondary venturi thing when optimised could make for a better mixture preparation than the simple annulus of the Keihin/Mikuni

When I used to play hot up with Alfa Romeo 4 cylinder engines many of these came with Dellortos, and some with Webers. It was reckoned that the Dellortos worked slightly better at part throttle and in transient situations. Slight differences in design resulting in more complete atomisation of the fuel was the reason.