The carb that Fuji uses on thier four stroke engine is basically the same carb as what is used on a Zenoah G-26. It is not the stock carb for this engine. The reason they use that carb is its easier to adjust high and low needle settings. The OEM Stock carb for the Fuji engine is actually a Walbro WY carb. This engine is actually a high end string trimmer engine. I have upgraded to a larger series Walbro WYT Series carb. I have a detailed 4 page repair manual from Walbro on this carb that details the adjustment.

Just about any Walbro carb will work for this engine.