Hp-carb selection graph

[Just Joel]

All the more reason I should switch to a 24mm instead of this d*** 28mm!

[Rip_City_Spree]

My 24 on my Corsa is plenty

[veedubh20]

tuning carb is trail and error..
28mm carb work good on hawaii climate..


the polini cp 21mm, inlet was measure 28.5mm

[veedubh20]

All the more reason I should switch to a 24mm instead of this d*** 28mm!

lol

[1man8scoots]

tuning carb is trail and error..
28mm carb work good on hawaii climate..


the polini cp 21mm, inlet was measure 28.5mm

You don't measure the inlet at the filter end..Its the center.

A 28 was too large for my 72 MXS mina vert, which makes an advertised 19hp. Can anyone explain why the larger carb would work better in hawaii?

It doesnt. They're probably are compensating for air leaks. Those charts are made by engineers with thousands of hours of r&d yet some people on the island just think they know better. Just like they claim theyre running mhr cylinders over 450 constantly. Yeah right. For shame, for shame.
The rest of the great tuners and engine builders who are truthful know 28mm isn't for a these tiny engines.

**edited for "the love of being pc" which I lack.

[1man8scoots]

It's the same mentality that the cps inlet size matters are the same few challenged individuals that think a 28mm is perfect for a 72cc.. The venturi is the ONLY factor. I run 26mm carbs on stroked and bored 244 cc 20++ hp blaster engines and 28mm carbs on stroked and bored 68 whp 421cc banshees. And on my stroked and bored 29 hp kx65/82 I run a 24mm.
I have real people who have rode my bikes on this forum who can verify my engines run amazing with these carbs. So amazing they're scary.
In order to run a 28mm carb on the mxs kit to hit 19 hp they have a full race set up and that cylinder isn't truly for the street so it is designed to run with in the race world parameters. Such as never dipping below 9k rpms.
The truth is out there you just have to be willing to listen to those who have put the real time into the r&d. Further more... if these people know better than these professional engineers and developers, why are they not in job positions that suit their "skills".

[Wheelman-111]

Greetings:

The carb size is determined by the diameter of its venturi, the narrowest part of the Hourglass shape that creates the negative pressure to draw fuel. You can measure the slide bore or the slide itself, but not the bellmouth or the spigot. OKO carbs for example ALL have the same 50mm bellmouth diameter.

Tuning can compensate, partially, for an oversized carb, but it's challenging to get it running right at low, middle, and high RPM. The carb only starts to work properly when the revs head for the moon.

For the record, I gained about 2 MPH, to 71.2 from 69, when I switched from a 24mm to a 26mm OKO. Low end was acceptable, but fuel consunption was pretty high and the Corsa needed over 10, 400 RPM for optimum thrust. Not much fun on streets with frequent stops. I believe with more tuning I could eventually have gone as fast with the 24, maybe even a 21, but the bigger OKO was sort of a shortcut to bragging rights.

[Just Joel]

I just jetted in a 28mm oko on a corsa 72cc bore... 154/55 in order to deal with the low vacuum/air velocity due to the large (too large) venturi. These jets are massive and are obvious compromise/compensation. Like stated, it provides adequate pull through all stations but literally drinks fuel. My little spree tank doesn't last long lol. Will be moving to a Polini 24mm setup. Best way of looking at it is if you actually down jet with a smaller venturi, your over carbed.

[veedubh20]

Lol

[Kevinstonge]

Hmmm. Anyone have an idea of what polini and malossi af05 bores are at for HP? Can't imagine it's much above 8.