49cc wont hold idle in the cold

[callmedoc]

Winter is coming


My 49cc scooter (Spark RSS, a chinese brand) cant seem to hold an idle. It starts just fine, but I have to keep the throttle held to keep it running. It doesnt matter if I've been riding it all day or I just started it in the morning.

I tried tuning the air/fuel screw counter clockwise so it runs more rich but that only seemed to make the problem worse. 4

Some background. It has an autochoke. My carb is brand new. I put a new spark plug in 2 months ago.

I'm still an amateur, but any advice would be appreciated. 

[fortyeight]

auto choke knaft,or try ajusting the trottle screw first

[RustyPop]

Nov 10, 2017 14:09:06 GMT -5 fortyeight said:

auto choke knaft,or try ajusting the trottle screw first

2t or 4t ?, if it is a 2t and you turn the air/fuel screw anti clockwise you will make it more lean not rich

[cagiva4ever]

as this is 4T section, i assume its 4stroke ?

in short, points into Lean idle circuit setting.

BUT as you say its NEW carb, so it needs Complite dismantle check, anything else is not doing it right.

as its Colder weather, if it has #31 idle jet, would be better with #34.

but that is not the only thing to check, as you say carb is NEW, that mean basic check(s) like "Float Height" should ALWAYS be checked/measured.

name the engine code and carb model 1st.

if its basic 139QMB or QMA, and carb is like PD18J or PD19J (not DENi or other with Flat in level Bowl surface..) , then this is about Best photos etc for you in whole web:

49ccscoot.proboards.com/thread/1651

www.youtube.com/watch?v=g6y32Gw5HK4

Point being, have it "Float level" out of spec, and you will never ever have anything from the carb settings Equal or Comparison able to any other Equal etc model carb.


if the Scooter lacks from scheduled maintenance, do also basics like check for AirLeak's in COMPLITE intake path or parts, every single 1.


you'r happily welcome to post up link/photos of your work and findings.