FS .26 4 stroke carb question
05-10-2004, 09:12 AM
#1
FS .26 4 stroke carb question
The problem is: when attempting to start, a large (lots!) quantity of raw fuel blows out the exhaust. I have checked the valve adjustment and its ok and compression seems ok. The engine is definitely flooding (badly!).
When one screws in the needle valve, should one see the tip of the needle "peek" out then end of the venturi tube?
Is there any other explanation for the extreme amount of raw fuel blowing into the exhaust?
Help please
When one screws in the needle valve, should one see the tip of the needle "peek" out then end of the venturi tube?
Is there any other explanation for the extreme amount of raw fuel blowing into the exhaust?
Help please
05-10-2004, 01:17 PM
#2
My Feedback: (11)
RE: FS .26 4 stroke carb question
If your O.S. Max FS-26 is flooding, it's because it's being over-primed, or the engine's side-mounted or pointed down. If the engine's upright, it's hard to flood it, because fuel will run out of the intake.
Check how you are choking the engine. Being a bit on the wet side is usually what's needed when starting a four-stroke engine. If it's flooding by itself, then your tank may be too high and fuel's siphoning into the carb and then into the engine. This is likely to happen only on side-mounted engines or ones where the cylinder head in pointing down. Hydraulic lock then starts to become a problem.
Basically, before cranking the engine to start it, turn it slowly backwards a few revolutions by hand to remove any excess fluid.
If the engine's running and blowing a lot of fuel out of the exhaust, then your mixture's just very, very rich. Depending upon how much running it's had, you can afford to lean it towards peak RPM.
AS far as the needle's concerned, the tip of the high-speed needle should be nowhere near the end of the nozzle when it's screwed all the way in. Your engine's needle seat has been damaged and the needle may not be regulating properly. This would cause difficulty in getting a running engine adjusted.
Check how you are choking the engine. Being a bit on the wet side is usually what's needed when starting a four-stroke engine. If it's flooding by itself, then your tank may be too high and fuel's siphoning into the carb and then into the engine. This is likely to happen only on side-mounted engines or ones where the cylinder head in pointing down. Hydraulic lock then starts to become a problem.
Basically, before cranking the engine to start it, turn it slowly backwards a few revolutions by hand to remove any excess fluid.
If the engine's running and blowing a lot of fuel out of the exhaust, then your mixture's just very, very rich. Depending upon how much running it's had, you can afford to lean it towards peak RPM.
AS far as the needle's concerned, the tip of the high-speed needle should be nowhere near the end of the nozzle when it's screwed all the way in. Your engine's needle seat has been damaged and the needle may not be regulating properly. This would cause difficulty in getting a running engine adjusted.
