Mid 80's Honda BF75L Idling Problem

[yjanray]

So after fighting with the recoil starter for 2 weeks, I finally got the thing put back together, and got this motor started. It will run, but will only run if i have the choke pulled out about half way and the throttle kept in the "start" position. It runs real high and I can' get it to idle at all. I don't know jack about carbs, so any guidance as where to begin would be great.

I bought the thing for 25 bucks. The PO said the thing wouldn't start after he cleaned the carb. So i just took the plugs out, cleaned them up, and sprayed some WD-40 in the carb intake and got it started.

I know the serial number is 170....not sure of the rest of the numbers, as I am at work right now. Just looking for some ideas as where could be a good starting point.

Thanks
Yorke

 

[Nick on the Bad Habit]

Re: Mid 80's Honda BF75L Idling Problem

Look at the picture.
The round brass colored screw is for air/fuel adjustment at idle. Turn that screw counter clockwise a half turn to richen the mixture and see if that helps. the other Phillips head screw is the idle speed screw.

 

[yjanray]

Re: Mid 80's Honda BF75L Idling Problem

Thanks Nick. Yoru carb is a little different than mine, but I think its still the same. The flat head screw on your picture (the air/fuel mix screw) has a spring on my carb, like the idle speed screw on yours. Anyway, I finally got the motor to run last night with the choke off. However, it would only run for about 15 to 20 seconds at a high rpm, and then start to die. I would give it a little rev, and it would run again at a high rpm for about 20 seconds. I tired messing with the air/fuel mix screw, but could not find a sweet spot. Does this carb have a float ball? could that be stuck or something? I know nothing about carbs, as you can see.

thanks for all of your help

Yorke

 

[Nick on the Bad Habit]

Re: Mid 80's Honda BF75L Idling Problem

The carb does have a float and very small fuel passages, that can plug up very easy. Look at the bottom of the float bowl for a drain screw, open it up and give the priming bulb a few squeezes. Fuel should flow easily. I would also change out the fuel filters. If that doesn't do it, it's time to pull the carb and do a through cleaning.

 

[yjanray]

Re: Mid 80's Honda BF75L Idling Problem

alright, well I got the motor to stay running, however the rpms seem a little high to be the proper idle speed. when i give it a little gas, it will rev up, and the settle back down and stall out. and after it stalls out, its a pita to start up again. I think i'm gonna have to take the carb apart, however apparantly the PO tried to take the bowl off, and stripped the screws holding it on, so theres no way to get a grip on the damn screws.

I also took your advice, and opened the drain, and pumped fuel through the system, right through the drain. it seems to flow pretty freely. i see an in-line fuel filter and a little tiny fuel filter under the front screw on the fuel pump on the front of the motor. That fuel filter is crushed.

I guess I need to break down and buy a manual, or at least find the section about the carb.

 

[isaksp00]

Re: Mid 80's Honda BF75L Idling Problem

I have a BF8A that stalled when put in gear at end of last summer, unless it was revved up too high with the throttle. Carb looks identical. Mine ended up having a clogged low speed (idle or pilot) jet.

The two screws in the photo on the carb body are the pilot adjustment and the plug that holds the pilot jet in. I can't recall which is which, but one consists of a needle when you unscrew it, and the other hols in a tube like jet. In mine, that jet had the very narrow hole down its center clogged. I soaked it in carb cleaner and used a single thin strand of copper wire (from a larger stranded wire) to unclog, and soaked some more, and then blasted air through. Motor seems to run fine now, in a garbage can of water. May be your problem as well, since this seems to control how the engine runs at idle, when the throttle plate is mostly closed.

 

[yjanray]

Re: Mid 80's Honda BF75L Idling Problem

Thanks. I figured a clogged jet or something was the problem. So I took the carb off, and took the bowel off and soaked the carb in carb cleaner for about an hour. then took a fine wire, and kinda scraped out the gunk left in there. after the thing sat in cleaner for a few minutes, the cleaner was brown in color and all of these really fine particulates and dirt was in the bottom of the can.

So after i cleaned the carb, i put it back on and it was still running rough. so i took a little screw off that is right above the fuel inlet, and sprayed some more cleaner down there, then a little wd-40 in the intake, and the thing started running smoothly, but with really high rpms. so i started adjusting the idle speed screw, and sure enough, I got the thing to pur like a kitten. I was so happy, and it seems to be running really well now. will start with just a half a pull of the starter, and shifts in and out of gear great, no hesitation, grinding or anything like that. Havn't had the chance to run it on the lake yet, but i'm hoping to soon.

Anyway, that was a really long rant just to say I got it running again. Thanks for all the help.

Yorke

 

[yjanray]

Re: Mid 80's Honda BF75L Idling Problem

I changed the engine oil yesterday. So where is the oil filter. I looked all over. Theres a little note on the side of the motor that says oil filter under cover, but not sure what that means. i can't seem to find it anywhere.

 

[isaksp00]

Re: Mid 80's Honda BF75L Idling Problem

My BF8A does not have a replaceable oil filter - at least, not like a car where it is designed to be replaced easily. I think there is one buried inside the engine somewhere, but it requires some dis-assembly. My shop manuals are not where I am right now, so I can't check.
Peter

 

[Nick on the Bad Habit]

Re: Mid 80's Honda BF75L Idling Problem

You can to this website http://marine.honda.com/owners/manuals and down load a free owners manual.