To manual choke or not to manual choke, that is the question

[TheAmishSasquatch]

I opened the fake intake scoop on the air box cover with a dremmel as a real intake. Im running a stock closed one atm for tuning baseline reasons. If anyone wants to buy my modded cover pm me.

[Scootsuper9]

Oh I deleted the snorkel a while ago and never had a water issue with water. The hose that goes from airbox to the Venturi of the carb is usually very small and causes a great restriction so people usually replace that with a 20mm radiator hose. And in support of the uni, it looks way sicker than the airbox too. Took the scoot in pouring rain and didn't even have a slight issue after parking in the rain.

[TheAmishSasquatch]

Cool to know, any pics of said mods?

[Scootsuper9]

Ya. I didn't mess with the airbox but this is what that person did

[Triesandluth]

Out of all the things I "know", I still feel like I don't know how the bigger carb or more airflow would affect my current performance beside mileage drop.  I feel like with what I have that it real couldn't do much more.  Maybe it drives up the rpms faster? 
I feel daft...

[TheAmishSasquatch]

Thanks for the pic, it cleared things up a bit.  From your description i had invisioned no air box, a 8in piece of black radiator hose with a cone filter at the end; making it look as if there was a big black shlong hangging off your carb 
I guess a picture is worth a thousand words

[BettinANDlosing]

Out of all the things I "know", I still feel like I don't know how the bigger carb or more airflow would affect my current performance beside mileage drop.  I feel like with what I have that it real couldn't do much more.  Maybe it drives up the rpms faster? 
I feel daft...

A larger carb will significantly increase power output. Too large will suffer on the low end, 19mm is a good balance between large and TOO large.

[Triesandluth]

Thanks,  that's what I figured would be the answer.  Not sure why I can't wrap my head around that.  So,  if not too large it would help in low end and top end? I could use a touch more low end...

[BettinANDlosing]

Thanks,  that's what I figured would be the answer.  Not sure why I can't wrap my head around that.  So,  if not too large it would help in low end and top end? I could use a touch more low end...

http://en.wikipedia.org/wiki/Venturi_effect
read this. It's a counter-intuitive thing to wrap your head around. A larger diameter will flow MORE but at slower airspeed, a smaller "venturi" will flow less but at higher airspeed, and carbs rely on airspeed more than the amount of air flowing in. So carb size is a balance between AMOUNT of air, and keeping that air moving fast. The larger the engine, the more "suction" will speed up airflow letting you use a larger carb. 19mm will add acceleration and top speed without sacrificing any performance, that is once you get it tuned good. I have like 5 needs, 3 slides, 20 main jets, and 5 idle jets for my Dell' 19mm "black" to get it tuned just right. A matched intake and 19mm carb will wake ANY bike up.

[TheAmishSasquatch]

So I think Ill pull the trigger on the Dellorto PHGB, anyone have experiance with the 17.5mm version? Im leaning towards 17.5-18mm as our scoots are only rated at a little over 4hp. Im worried that 19mm will be just slightly over sized and any potential hp gains to be had would be negated due to the out of spec size per available hp and displacment. My goal is to fine tune the carb for max performance and not waste time having to de-tune it to optimal condition due to too large of venturi.

[BettinANDlosing]

So I think Ill pull the trigger on the Dellorto PHGB, anyone have experiance with the 17.5mm version? Im leaning towards 17.5-18mm as our scoots are only rated at a little over 4hp. Im worried that 19mm will be just slightly over sized and any potential hp gains to be had would be negated due to the out of spec size per available hp and displacment. My goal is to fine tune the carb for max performance and not waste time having to de-tune it to optimal condition due to too large of venturi.

Do you think you'll ever want to go to 70cc? If so you will regret not getting the 19mm. My 19mm feels awesome on my zuma and it's still 49cc stock cylinder. Get the dellorto black 19mm, thing kicks ass.

[TheAmishSasquatch]

How rich of main are you running and what needle position?  Pilot jet/air corrector?

[BettinANDlosing]

One thing with the PHBG dellortor, you'll want to get the AU nosle, because the carb comes out of the box setup for 4t. https://www.treatland.tv/dellorto-PHBG-atomizer-AU-p/dellorto-phbg-atomizer-au.htm

I am running an 88 main and 38 idle, that should get you close but the zuma takes funny jetting. Get a #9 and #12 needle, they work the best for me. I think the black comes with a #7 needle that is hard to tune with. Treatland has everything you'll need for that carb. Highly suggest getting a larger intake to match the carb also, not sure where to get that for the Kymco engine, but they are out there.

[Scootsuper9]

I still use the stock mani with my dellorto. Is there really a noticeable difference with a bigger intake?

[TheAmishSasquatch]

Thanks for the link, I will look into that. I have a set of pilot jets coming in for the PB 14 as I know for fact my bike ran like a raped ape when it was in tune. Ill try tinkering with that and it will be my carb that goes with the bike if I ever sell it, keeping the Dellorto for my self