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BF 40 Idling

J

JPasadena

New member
I recently purchased a 98 BF 40, motor sat for a while so prior to running it I completed the following maintenance. I did run it with muffs which kind of initiated the maintenance performed.
Changed fuel filter, Spark plugs"checked gap per Honda spec",low end oil, motor oil, oil filter, t-stat, clean all three carbs which were gunked up also replaced carb gaskets. The boat has fuel thats approximately 2weeks old no additive. I ran it for the first time last night, ran great at high rmps but would not idle. Confirmed fuel tank was vented. Primer ball and fuel line are old but no visible cracks or holes. I did not replace the jets, If anyone has any suggestions it would be greatly appreciated.
 
Idle mixture screws (pilot screws) for that year should be 2 1/4 turns out.

Make sure engine is coming to temperature. If you do not have temp gun, just grab the oil filter and it should be warm enough that you can keep your hand on it for a while, but not keep it on for a long time.

If that does not work, the jet sets should help, as long as you have cleaned the entire idle passage.

If you can get the motor to run at all at idle, pull the spark plug wires one at a time and see if the engine rpms go down. If it does, then that cylinder is probably ok. If there is no change, then you have an issue with that cylinder.

Listen for the tick tick tick of the spark when you pull the wire off (holding the plug wire cap just over the spark plug).. that should be a pretty good indication that you have spark.

If anyone has messed with the vacuum balance screws, that can keep a cylinder from operating at idle also. So, when finished, vacuum balancing carburetors is really important for good idle.

I generally set the idle a little high when on a hose....about 990 -1000 rpm.

Mike
 
I replaced the jet set and my idleing issue seems to be corrected. I would now like to vacuum balance the carbs. Whats a good set of gauges to purchase and or what else will I need. I found the procedure it just doesnt give me specifics on tools required ect..
 
JPasadena said:
I replaced the jet set and my idleing issue seems to be corrected. I would now like to vacuum balance the carbs. Whats a good set of gauges to purchase and or what else will I need. I found the procedure it just doesnt give me specifics on tools required ect..
Click to expand...

I dont know how good quality they are compared to others, but I bought the MotionPro gauges on Amazon and they worked great for me.

http://www.amazon.com/Motion-Pro-08...239103&sr=8-2&keywords=pro+carb+vacuum+gauges
 
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