50cc engine swap By cyborg (Read 701 times)

[tyler20]

Hi Everyone,

I recently did an engine swap on my Tao Tao Scooter (prev engine had a cracked engine block and was leaking oil). The new engine is also a 139QMB engine.  I bought a brand new 18mm PD18J Carb for it as well hoping to avoid any further issues.

Once I swapped the old engine and put on the new carb, the scooter Idles great, but it takes a while for it to accelerate off the line.  Almost feels like it is running Rich and bogging down.  (does this going up hills as well)

Before I remove and exchange the jets, I've read a few times online that new engines have a "break in period" and was just wondering if that is something that will get better as I continue to run the new engine and "break it in."

ALSO - I live in Denver where we are at 5,000+ Ft above sea level.  I've read online that a re-jet is crucial as you gain elevation...

Any help is much appreciated!

[cyborg]

Yes a rejet is in order,,I'd drop down a couple in the main jet,,that should do the trick,,,,,as far as break in first off drain the junk oil they send the engine with and the final drive gear case oil it's junk as well,,,I'm a run her hard break in guy varying throttle positions and load for the first 150-200 miles drain the engine put new oil and run her

[czmdiver]

Question. is the Carb off the Original Engine?
Before you buy some jets and get into this please pull the park plug, take and post some pictures to confirm Rich or Lean.
There are some good tutorials here on this site to help you with Jetting since you've never done it before,
No this the CVK carb (Constant Velocity) is very forgiving so you would have to make drastic changes or may not at all.