Main Jet - Kymco Like 50 4T

[c.stroe]

Hi everybody,

I have a Kymco Like 50 4T, basically the same engine as the Agility.
Well, I have installed an Airsal 80 CC kit, a Malossi Multivar 2000 variator and a 17/49 secondary transmission gear up kit from Jasil (Top Racing).

What would be the best main jet size?

I live in a city about 60-90 meters above sea level (196 - 295 feet), temperatures are moderate.

The idea is that the scooter moves really slow from stand still and top speed is low. If I pull the throttle suddenly, it just chokes and doesn't accelerate.

Thank you,

Cristian.

[OaklyJava]

Sounds like you could use a carb upgrade like a 150 carb.

Sent from my SM-G950U using Tapatalk

[JJJoseph]

Sounds like you could use a carb upgrade like a 150 carb.

Disregard this suggestion!  The 150 carb will make a total mess of your upgrade!  This is a simple mixture tuning problem, and you fix it by finding the right jet(s) for your stock carb.  It's easiest with a selection of jets from 85 to 95 main jets, and 35 to 42 low-speed jets. They're standard Keihin jets, easy to find online (Keihin Small Round 99101-116 Main Jet & Keihin N424-22 Pilot Jet  from here:http://www.pjmotorsports.com/keihin-jets.html) Make sure the jet size is stamped on the side of each jet. Your air filter affects mixture, and you might find that a simple cone filter is the easiest for tuning. Start by swapping the low-speed jet until you find one that launches cleanly.  Then swap the main jet until you find the one that accelerates clean from about 40 km/hr. If you live in a location that goes from hot in summer to cold in winter, your scoot will change its manners with the seasons as the fuel/oxygen ratio changes.  Mostly, you'll be able to live with this minor quirk.  Later fuel-injected models don't have this quirk.

Starting your scoot will be affected by the compression ratio.  A BBK with the stock head will have higher compression and might be hard to start.  That's a whole other discussion!