BF 50 Honda runs great except acceleration problem

Joined
Jan 7, 2007
Messages
12
I have a BF50 Honda that idles great and runs great, except one problem. If I slowly or sort of medium-ly apply the throttle it steps up without hesitation, but if i just crank on the throttle quickly it will stall or nearly stall before picking up again. I had it in to a mechanic last week and he took the carbs apart and said they were clean as a whistle, including the idle jets. He also checked that valve on top of the carbs (I forgot the name of it) At first he thought that one could have been the problem.
He is going to check a few other things on Monday but if anyone has experienced this or has ideas please let me know.
Thanks Graham
 

MattFL

Master Chief Petty Officer
Joined
Oct 20, 2010
Messages
827
Re: BF 50 Honda runs great except acceleration problem

I have the same motor and I know exactly what you mean. You open the throttle fast and the power cuts out for about half a second then suddenly you have full power. This is a lean condition, 4 strokes do this when they are lean. Mine does this on cold days or before the motor is fully warned up. Also old gas and gas with lots of ethanol seems to make it happen more. Also mine will do it after extended time going slow which allows the motor to cool off. When its hot it doesn't do it. Some 4 stroke engines use accelerator pumps that shoot a bunch of gas in when you open the throttle to prevent this but this engine.doesn't have one. A dirty carburetor could definitely make this worse so if yours is bad then cleaning the carbs is a good start. Mine doesn't do it that much so its not really an issue. I hope this helps, let me know if your mechanic solves it completely.
 

MattFL

Master Chief Petty Officer
Joined
Oct 20, 2010
Messages
827
Re: BF 50 Honda runs great except acceleration problem

I will add that I bought this motor new in 1999 and the issue has come and gone over the years. My theory is some thermostats open earlier than others allowing the motor to run cooler and this makes the issue more pronounced. That's just a guess. Did you just get the motor?
 
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