honda bf20 hard to start

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extremes

Recruit
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Sep 5, 2007
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Hi, I own a Honda BF20 (2008). Lately it became very difficult to start when in water both when cold and when hot. When it is on land, it starts with the first try!
Also, at mid throttle, there is a gap where it does not respond to the throttle and at this gap, it sometimes swith off. So when you are at low/medium revs and you want to accelerate, it either switch off or the revs go down and then goes up.
Any suggestion what's wrong?
 

MattFL

Master Chief Petty Officer
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Oct 20, 2010
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827
Re: honda bf20 hard to start

Sounds like the carburetor needs to be cleaned out, you probably have a clogged jet.
 

mf70

Cadet
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Aug 7, 2015
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As I understand it, the Honda carbs for the 15's on up have four separate fuel delivery circuits (numbers are from the Honda parts fiche images):

1) The FE (fuel enrichment) circuit, equivalent to the choke on conventional carbs: A piston #11 is lifted when the knob is pulled, opening a connection between the vacuum BEHIND the throttle plate and the intake silencer. A metered jet (one of the tall brass tubes on the body) is also uncovered, allowing fuel to be sucked up at the same time. When the throttle plate is opened, there is no vacuum, and no extra fuel is delivered.

2) The idle circuit: fuel is supplied and metered through the pilot adjustment screw. Idle throttle is set through the main throttle stop.

3) Main supply circuit: Fuel is supplied to the jet #13 and main nozzle #14 from the main jet #19.

4) Accelerator pump: additional fuel is actually pumped from the float chamber (through the second tall brass tube on the body) to a tube extending into the carb throat outside the throttle plate.

For extremes, it sounds like the idle circuit or the accelerator pump circuit is clogged..
 
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