Honda 15 - stutter at higher RPM ...And a minor miracle!

Wandering Sagebrush

I'm getting the tinny ready to go chase a few Kokanee, and noticed that my 15 horse is stumbling at higher RPMs. It's very smooth at idle and mid range. Sounds to me like it's only one cylinder that's hiccuping. It happened last year on my last usage, too, but as I ran among at mid range, it gradually smoothed out. I'm thinking either a plug or something in the ignition system, but I won't rule out a carburetor jet.

Your thoughts?

Now for the good stuff. I have a Honda Classic 8 on the tinny, too. It hasn't been used much for years, so I thought I would see how it does for trolling for kokes. In the past, it has always been a BEAR to start when cold. Ryan at Sportcraft told me to pump the bulb up, put the engine in gear, open the throttle wide, a light squeeze on the bulb, then close the throttle, go to neutral, and pull the rope. Damned if it didn't fire on the first pull. Didn't even have to choke it.

A miracle! I can't tell you how many times I've fought that little beast.[/b]

ssobol · Posted: Sat May 30, 2015 4:16 pm Post subject:

Don't know why putting it in gear would make a difference, but the rest of it makes sense. The acceleration pump will squirt a bit of fuel when the throttle is opened.

Wandering Sagebrush · Posted: Sat May 30, 2015 4:41 pm Post subject:

digger · Posted: Sat May 30, 2015 4:46 pm Post subject:

I think what it does is allows the carb butterfly to close totally, giving it a better vacuum for the engine to suck the fuel to initiate the start. Look closely, and I think you will see that the linkage closes a slight bit more when you go through that scenario. I noticed the same think on a Tohatsu I had. My 8 Honda did it also.

Sunbeam · Posted: Sat May 30, 2015 5:47 pm Post subject:

I thought this might be interesting to re-post here, talking about the differences and how the A vs. D model work in starting. I had copied/saved this from the archives here because I had a Honda 8hp "D model" (the "other" model). It's a post made by Les Lampman of EQ Marine who was a Honda dealer and mechanic. The engine being talked about above in this thread would be the Honda "A" model (the squarish 8 hp).

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There are two "models" of the Honda BF8; the "A" model and the "D" model. Since 2001 they have been built concurrently. The "A" model is the updated version of the old blue and white BF100 and has a squarish hood. The "D" model was an all new design (and it shares its block with the BF9.9D) and has a very round hood.

This is important because the "A" model has a traditional choke plate in the carburetor. The "D" model has no choke, even if it has the choke knob you're really pulling a needle valve out of the carb's enrichment circuit; it works exactly the same on the electric start models which do it with electricity (by heating a disc) rather than a cable as on the manual start versions.

To reiterate...the "A" model has a choke; the "D" model has an enrichment circuit. The end result is the same...to get a mixture in the cylinder that will fire but they come at it from totally opposite approaches. The "A" model choke plate restricts the air intake to richen up the charge in the cylinder and the "D" model adds fuel to richen the charge in the cylinder.

Why is this important? Because on the "D" model if you so much as breathe on the throttle handle you'll introduce more air into the fuel mixture and lean it out...it will not start. It must remain in the dead idle position and not be moved until the engine is idling on its own. Resist every temptation to turn that throttle handle; you're just undermining your efforts.

Here's a bit of a tip but please read carefully. BEFORE you ever pull on the starter cord and after you've connected your fuel line and primed the carb you can twist the throttle handle all the way open a couple of times. The "D" model carb does have an accelerator pump and this will give the engine a couple of shots of fuel. Then return the throttle to the dead idle (i.e. - against the stop) position, pull out the "choke" (really enrichment) knob, and start the engine. Feed the knob back in as the engine starts to warm up. NONE of this applies to an "A" model BF8.

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Funny thing is that even after having read this, I had a problem once starting my 8D. Yep, I had completely forgotten about it and "breathed" on the handle. Stopped doing that and all was good Very Happy

Wandering Sagebrush · Posted: Sat May 30, 2015 6:48 pm Post subject:

Sunbeam · Posted: Sat May 30, 2015 7:01 pm Post subject:

Wandering Sagebrush · Posted: Sat May 30, 2015 7:09 pm Post subject:

Sunbeam · Posted: Sat May 30, 2015 7:25 pm Post subject:

Wandering Sagebrush · Posted: Sat May 30, 2015 7:35 pm Post subject:

Sunbeam · Posted: Sat May 30, 2015 7:41 pm Post subject:

It could be a great conversation piece: "Why does one of your motors say "breathe" on the cowling, and the other one say "don't even think of it"?

Wandering Sagebrush · Posted: Sat May 30, 2015 8:05 pm Post subject: