Honda BF75 Idle problems

fishnhuntnfool · 04-01-2007, 04:06 PM

I moved from the valley (Hillsboro, Portland) to La Pine in June of last year and haven't ever been able to really dial in the carb for the higher altitude. I can get it to run in the start position but I can't get it to idle down to the shift position. When I run it out on the lake by starting it in gear it seems really bogged down. Last summer I changed the plugs and cleaned out the carb. Trying to get it ready for this spring and I can't get it to idle even after letting it warm up for 10-15 minutes. It's a BF75 (Older honda 7.5 4 stroke with a Keihin carb). Any ideas? Also the float seems to stick, I.E. when I pump the fuel ball, fuel spits out the bowl vent and then I'll tap on the bowl and pump more and it stops, then it will start. PM or respond please!!! All help is appreciated.

luckyr · 04-01-2007, 07:48 PM

Kind of sounds like idle jet may be clogged. Did you clean the jets? when you took it apart before did the needle get seated correctly. Or some of the goop that has clogged your jet may be preventing you needle from seating. The fuel air mixture from altitude should be that hard to achieve after it will idle. The rule of thumb is screw in mixture screw until it seats and 1.25 turns out for you it may be 1.75 turns out It is worth exactly what you paid for it. (my advice that is) Good Luck

fishnhuntnfool · 04-01-2007, 08:30 PM

I thought I had cleaned the idle jet. Does anyone have a breakdown of this carb (it seems to simple to need one, but I haven't dealt alot with carb teardowns). Could you tell me where the idle jet is? I pulled the mixture screw/needle, opened the bowl, cleaned out the center pieces in the bowl, and sprayed carb cleaner in every hole I could find. I have tried adjusting the carb from 1-3 turns at 1/4 intervals with no luck. Also after running the motor today I checked the oil immediately after shutting it down and there were bubbles in it... not like water was in there as the color wasn't changed, but just little air bubbles? Maybe the oil needs a changing too? (I know this wouldn't effect the idle, but oil is probably due)

luckyr · 04-02-2007, 07:22 PM

After you take the bowel and the top off you should see two standard screw driver heads with a hole in the middle. Small one is your idle and larger one is run speed. They will be brass rods the have horizontal holes in them. With a bright light behind you should be able to see through these holes. If one or more of these are clogged you idle will be rough at best. Run a needle through and rinse with carb cleaner. Clean them several times maybe soak over night in cleaner. Reinstall and close up carb clean and correct are the key. You should be able to re use gaskets if you were careful. Becareful when you use the needle in jet holes you dont want to make them any bigger. One other problem I ran into was the fuel line was just as dirty as carb so I replaced all under the cowling fuel lines and put a new in line filter.
Last year at the boat show I was with a freind of mine and he has the same motor as you and had some smoking problems when the motor first started. We were talking to Larry from sportcraft in OC and he told him to rinse out some tube but for the life of us we cant remember what exactly what he told us. Call him or talk to Tim maybe they can help you out a little. They do make a living fixing Hondas but maybe if you turn on the charm you can get some good info.
The bubbles in the oil? I dont know. One thing the fuel bypassing out with bulb has me puzzled. Good luck