BF100 rpm double when shifted into forward

Hi -
I have an 80's BF100. After a month or more of sitting it always starts on the 2nd pull and idles fine (1st pull with the choke pulled all the way out...the engine fires a couple of times but doesn't start; push in the choke and pull and it starts up fine and idles normal).

The problem I am having is when I put the engine in forward (without touching the throttle) the engine's rpm double. If I put the engine back into neutral or reverse...the engine returns to a normal idle.

Any idea?
Thank, Leif

Are there any bare wires near the shift linkage ??

Racerone,

Thanks for your question. I'll check for bare wires when I get home tonight. I think there is some electrical tape that is starting to show signs of wear at the base of the tiller handle (where the tiller pivots vertically).

Not being able to look at and touch your motor I have to ask ------------Is it running on both cylinders in forward and only 1 in nuetral and reverse ???--------------Are any throttle linkages at the carburetor moving when you shift it ??

Racerone,

Checked for bare wires on the tiller and inside the housing. All wires are fine. However, where the tiller pivots, I noticed two places where the throttle cable’s outer cover was worn and exposing the inner cable. Both places had signs of rust. I also noticed a little rust on the spring that returns the carburetor back to idle. With the engine off, I cycled the transmission a couple of times from neutral to forward and could see that the carburetor linkage moving slightly. You were right about checking for movement in the throttle linkage.

I believe that the throttle governor? (the metal plate that prevents the throttle handle from turning past the START mark when in neutral or reverse) was maintaining extra pressure on the throttle cable due to the rust spots on the cable and/or the idle return spring. Once the throttle governor was retracted (only by shifting into forward) the tension on the cable was released causing the carburetor linkage to move enough forward to double the rpms.

So I sprayed the throttle cable ware spots and the entire shifting linkage, throttle linkage, and idle return spring areas with WD-40 and cycled the throttle from idle to full-throttle 20 or so times with the engine off and the transmission in forward. I also cycled the throttle from shift to start with the engine off and transmission in neutral and with the transmission in reverse.

I started the engine (it started on the 2nd pull like always) and the engine idled normally in neutral. I shifted into reverse and the idle did not increase. I shifted the transmission into forward and the rpm stayed at the idle speed.

Looks like I can replace the throttle cable for around $15.00.

Thanks for your help!

awesome read RACERONE good insight !!!!!!!!!!!!

Nice fix you guys! Way to "git er dun".