People 50 carbs over the years

[mclark999]

Came across a few threads that seem to indicate that older models had larger carbs and that starting in 05, 06, or 07, the carb is smaller and performance is smaller as well.

I have an '07 and previous owner already derestricted the exhaust (took off the extra air passage and welded up the little pipe). Performance is decent, but not as good as what all the owners of older models claim.

I've got a performance exhaust on the way, but I'm wondering if I should replace the carb too.  If I want to just replace it with an older model, what am I ordering.  The manual says I have a 14mm carb, but everyone says it should be 17mm.

Thoughts?

[chaz35]

I have 05 People 50 2T.  I don't know about carb being smaller on later models, but I know the exhaust is definitely more restricted on later models.  If you have the carb off, measure the smallest inside diameter of the carb.  I think mine is approx 17mm.  I also have a Malossi 19mm carb I haven't installed on anything yet.  When I compare the 19mm to the 17mm carbs there doesn't appear to be a big difference.  When I take the throttle barrels out and compare them, the 19mm barrel looks significantly larger.

Kymco sells scooters worldwide, and I know in some countries the OEM carb is smaller than the one sold in USA.  I think that's maybe why you see specs that the carb is 14mm.  There is also an o-ring that goes on the back of the carb I have never been able to get the right size.  I am always sent something way too small, so I think some scooters come with a really small carb.  The carb is also called a Keihin PB16 when you look for jets.  It measures 17mm IMO, but maybe it's 16mm, I don't know.

With 49cc engine and Tecnigas NextR pipe OEM carb worked very well for me.  I installed 108 main jet and 45 slow jet, ran great, no problems, could run WOT all day.

With BBK I am still trying to get the OEM carb to work, the engine runs great, but gets too hot.  I have raised the needle approx 1/8", installed up to 52 slow jet, and drilled out the main jet to approx .050" (for comparison 108 main jet is approx .040") it still runs too hot, but getting better.  Next, I will drill out the main jet to approx .051 to .052" and see if that makes the difference.  At some point I may have the specs for what to do to make the OEM carb run well with BBK or I may conclude it doesn't work, that you need a larger carb.

Installing a larger carb is problematic IMO, the main issues for me are the throttle cable and oil injection.  I won't go into the details, but haven't installed mine yet, because for me it's not a bolt on mod, will take a fair amount of work and time to get it installed right.  Cheers

[mclark999]

Installing a larger carb is problematic IMO, the main issues for me are the throttle cable and oil injection.  I won't go into the details, but haven't installed mine yet, because for me it's not a bolt on mod, will take a fair amount of work and time to get it installed right.  Cheers

Hoping to not have to install a larger/different brand carb for the same reasons.  I don't want to deal with the cables.  I'll know more this weekend after I take the carb off to clean it up.

[mclark999]

Measured my 2007 when I had it apart. It's 16mm.

[mclark999]

When I installed my new Tecnigas Trek exhaust, I decided to open up my airbox to give it some more air. The snorkel is restricted with only a 1/2" or 12.5mm air hose coming in. So even though my carb is 16mm, it won't flow that well.

I started out by drilling a number of half inch holes in the airbox, trying to match the airflow with the 89 jet I installed in the carb.  It took a total of 5 holes to get the jetting right.  I calculated areas of circles, etc and figured out it was jetted best with 1.62 square inches of opening in the air box.

I measured the actual snorkel without the restriction and it is 1.62 square inches. Imagine that!  Almost perfect. So I pulled the hose out, cut out the restriction from the snorkel and sealed up all the holes I had drilled in the airbox.  It runs great like this.

So the stock highly restricted airbox on a 2007 matches up well with the super restricted pipe. I guess that's no surprise.  To upgrade to a high performance pipe, a cone filter isn't needed. You just need to take out the air box restrictions.  No cost upgrade.