Originally Posted by
oldiebutagoody
If your carb leaks at standstill you have either a fuel tap that is not shutting off properly, or a fuel tap that does not shut off properly in combination with a leaking float valve needle. Either way the float needle is the more immediate problem. It will cause too much fuel to be in the system at any given time and make it run rich. Trying to tune this out of the carb will end up with you chasing your tail as nothing will be ideal in all of the operation ranges.
Float needles have a rubber tip (rubber goes hard with age/heat/solvent exposure/time) which is supposed to be pushed up by the floats when fuel fills the bowl. If the float level is not set to (whatever the manual states) ....it will either starve or flood. If in combination with incorrectly set float level you have a float needle that has gone hard, or is binding in its housing then you get heavy fouling of the spark plug.
Simplest and least frustrating remedy is order replacement float jet/needle assembly (buy OEM and forget EBAY/TardMe), reset float level to factory spec, throw away the plug and insert new one. Honestly its not a lot of money, probably less $$$ than you have poured down the drain in fuel wastage.
Ask me how I know this..............
Things wear and need replacing with age (mechanical things also). A GN250 is not a complicated machine, get a manual or download one off t'internet, google search terms like " GN250 running rich, carb leaking fuel"
Bookmarks