Re: big derbi kit. Little Carb. Littlier intake.

Don’t need a big carb on a derbi, especially with the stock reed design. For that matter, stock av10, Peugeot, Puch Polini kits, hobbits and even tomos all run amazing with 15-19mm carbs. The stock reeds can’t flow much more than 19mm and while you can put a larger carb on, it kinda just ruins your gas mileage.

Reed valves also tend to smooth out one of the bigger issues with a sha. Like how if they’re tuned right for when the pipe hits and the top end of the rev range they generally will be rich in the bottom.

I don’t like performance of a sha that much, though it does still cruise at 50 no problem I feel like it could be smoother when I roll on from idle. I still don’t get the cutaway tuning.

I do however like not having to worry about running out of gas on group rides and never having to tune.

Re: big derbi kit. Little Carb. Littlier intake.

Dirty30 Dillon /

People tend to say that "XXX carb is too small for XXX" having no idea what they're talking about.

In an all out speed build, you can get more out of a bigger carb, but 15-19 is really the perfect range for the majority of bikes.

I think Jennings said for race applications you want a maximum of ~50% cylinder bore as your carb size. So for a gila'd E50, your ideal parameter maximum carb size is ~23.5mm. That said, for a daily rider you'll see a ton of benefits to running a 21mm carb or even 19mm, including better mileage, easier jetting, and increased low end response.

Re: big derbi kit. Little Carb. Littlier intake.

Emil Kniemel /

Wow, thank you for such great answers!

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