Trailmaster 300XRX carby issue

[Astroarthur]

Hi all and thank you for allowing me to join the forum, hope my little older "buggy" is allowed to be discussed on here.

This little machine (Trailmaster 300xrx) i bought two years ago and on arrival home it refused point blank to start. I contacted the seller who sent me a new carby which i fitted and now it starts and idles but accelerating is a nightmare. I am using the original main jet but my home is at 3200 feet above sea level, the seller was about 600 feet above sea level. It idles ok when starting but when accelerating bogs down to the point where you think it will stall and then it picks up and takes off like a rocket. This happens every time you take your foot off the accelerator. I don't know these CV carbies at all well. does anyone have any clues as to what could be the problem with the little demon? Also do i need to slightly increase the jet size due to the altitude or am i being pedantic . Thank you

 

[Master Hack]

Generally speaking, higher altitudes calls for smaller jetting.
the problem you're describlng sounds like you might have a have a vacuum leak.
spray a little starting fluid around the carb base (while its running). If you hear a change investigate.

 

[panchothedog]

Pull out the spark plug. If it is all black and sooty, then it is running rich and needs a smaller jet as mentioned above. Less oxygen at higher altitude, engine requires less fuel.