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adjusting the pitot screw and throttle stop on a BF15A?

J

Johnny One Niner

New member
Hello to all,

First time to the site so let me thank you all in advance for the good advise I've already got from you all. I have a BF15A on a small 15' runabout. Not enough motor for the boat but it putters me up and down Topok gorge on the Colorado River so I'm happy with that until I can afford a bigger motor. Kind a poor mans boat but I love it. A '63 Trailorboat.

My question is this:

Doing maintenance on my motor. Adjusting the idle speed. Recently put a tach on it. Reading about the pitot adjustment which is 1 5/8 out factory setting. Checked it and it was about 3+ turns out. I took it up to a mountain lake a few years ago and of it didn't have enough air so I opened up and must have never returned it.
I read a great article on adjusting the pitot. Put it back to spec, 1 5/8 out. says to start it, warm up, put in gear, then turn it one way and see if it speeds up or slows down. then turn it the other way and see if it speeds up or slows down. looking for the highest idle speed.

Where is the idle adjustment screw during this? So I get it to the highest idle speed adjusting the pitot then lower the rpm to the 1100 +- 50 with the idle adjustment screw? Should I have the idle screw high so I can then lower the RPM? I'm not sure which end of the idle screw adjustment I should be at to properly set the pitot.

I did, in fact, lose some top end speed along the way. Thinking this might be the culprit possibly?

I hope that makes sense. Thanks guys and gals!
 
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Ha ha,
There must be a misprint in your manual. I was scratching my head muttering "pitot screw"?

Ahhh, PILOT screw....it finally dawned on me!

Actually, in a perfect world, the idle adjustment screw should be backed all the way off the stop while adjusting the pilot (or mixture) screw.

If your following those instructions raises the idle too high, then I recommend going back to the specified 1 5/8 setting to see if that lowers the idle significantly. If so, you would then use the idle screw to raise the idle to where you want it. That's what the idle screw is for.

If you can't achieve these results then it's possible the carb isn't functioning properly and may need cleaning.

I believe that carb has a "slow jet" screw at the top and sort of in the middle of the carb body. Sometimes, taking that out and spraying cleaner in the passage, both ways, and on the screw can really help the idle so you might want to try that before removing the carb.

Good luck.
 
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Thank you so much jgmo!

I'm not sure where my head was when I posted but it as since cleared! Makes perfect sense now. I'll start at 1 5/8 out and adjust the RPM with the idle screw to the 1100.
Then try adjusting the pilot up and down the find the sweet spot, and then level the RPM back to 1100. so on and so forth until it is dialed in. I think I have it straight now.
Hoping this will get me some top end speed back. The pilot screw was a little over 3 turns out. Think I've leaned this one the hard way! lol

Thanks again my friend! Be safe out here.
 
That's good news Johnny 19er.
No matter how you arrive at a "FIX", we'll take it!
Happy boating!!
 
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