I noticed recently that my OS 50 SX is creating bubbles in the line between to needle valve and the carb...i have replaced the line and check every thing...it all seems fine...i have read some of the members on here have the same problem...do you have a fix for this..?is it a design flaw?

Thanks,

Peter

Bubbles in the fuel line between the needle and the carb on rear-needle engines can be caused by a number of factors. Most common is a needle valve that's become loose in the housing. If any kind of extension's been used, it can cause the needle to vibrate around and damage the holder.

A period of non-use can cause the o-ring to dry out and no longer seal properly.

Air agitated into the fuel in the tank can also manifest as bubbles between the needle and carb. They are micro-bubbles until they get to the needle, which provides a point where they can gather and then break off as larger bubbles.

A new needle or o-ring may provide a solution. If the needle seat's shot, you'll need a new needle valve assembly.

how often does the need valve or o-ring go bad...the engine is only 4 months old and gets used frequently....everything from the tank to the needle valve is new....so maybe faulty engine?..what do you suggest?

unbelievable i have the same problem in my 50sx the engine after break in.