Got a new dune buggy thing from China. I got it all put together, but I got a problem with it. It idles ok, but when I really step on it, it back fires during decelleration. It pops very loudly. My guess is with the carb. I live at 7k ft altitude here in Flagstaff, AZ my guess is this thing was setup for sea level? No instructions came with the thing. Now, do I have to rejet, or is there a setting on the carb? This is an air/fuel issue, right? Advice, Please!

should have fuel mixture screws on it unless its a non adjustable carb, which then while running and fully warmed up, it should then be adjusted if it can be, even try it under load.

I don't see a screw to adjust it. What do you mean when it is warmed up it should be adjusted?

thanks.,

might want to check for intake manifold leaks make sure its not leaking or might check the spark plug gap will it rev up if you ease into it ? or does it do it no matter what usually it is caused by a lean condition but there are a few other things that will cause it also do you know how to check for intake leaks ?

I don't see a screw to adjust it. What do you mean when it is warmed up it should be adjusted?

thanks.,
yes check what scrench said, its a chinese it may have a problem or few. but when its warmed up its at its best basically.

I don't know how to check the intake manifold for leaks. How can I? At idle, it's pretty quit, but as soon as I press the accelerater, it sure is loud....Don't know if that makes a difference.

It only back fires when I gun it full open throttle AFTER I take my foot off the accellerator...

is the muffler tight ? does it have the spark arrestor(baffel) in it ? the best way and the cleanest way i test for a leak is with a propane hand held torch un-lit just turn it on and hold it near the place you think it might be leaking if the engine speed changes then its leaking you can use wd- 40 or carb spray but i dont like it too messy if the muffler is leaking or has a hole in it it can cause it to pop or if the valves are off if its too lean or running rich you will just have to chase it down but i would start off with making sure its not sucking air anywhere if it is it can and will melt things in the combustion chamber , but it might be something simple causing it float level might be off , does it blow black smoke under acceleration ? is the idle set too low /

It only back fires when I gun it full open throttle AFTER I take my foot off the accellerator


over looked that ,, if you are rapping it to kingdom come its going to do it