Ported 390xp Fuelling issue.

[trappermike]

With your cyl. on put your motor at BDC (Bottom dead center) ,then take a slim sharp scribe and trace the outline of your intake port on the piston. Does the piston skirt still provide 2-3mm sealing on each side of the port? If so ok good.
Sounds like you may have a carb problem allowing tons of fuel; new kit,welch plugs sealing,inlet needle problem?
Oh yea... if your saw has a WJ Walbro carb you may have the wrong carb parts in it. The Walbro WJ carb rebuild kit had 2 different sets of pump diaphragms in it;there was a pump diaphragm and gasket included that never fit a single WJ I ever worked on,but if it's accidentally installed the carb will never run right.

 

[revyfaller]

With your cyl. on put your motor at BDC (Bottom dead center) ,then take a slim sharp scribe and trace the outline of your intake port on the piston. Does the piston skirt still provide 2-3mm sealing on each side of the port? If so ok good.
Sounds like you may have a carb problem allowing tons of fuel; new kit,welch plugs sealing,inlet needle problem?
Oh yea... if your saw has a WJ Walbro carb you may have the wrong carb parts in it. The Walbro WJ carb rebuild kit had 2 different sets of pump diaphragms in it;there was a pump diaphragm and gasket included that never fit a single WJ I ever worked on,but if it's accidentally installed the carb will never run right.

thanks, yeah was the carb. She screams now!

 

[trappermike]

Great!