5Hp B&S, Weird, hard start, cant control Rpm's


Old 07-04-08, 06:03 PM
hoary's Avatar
Thread Starter
Join Date: Jun 2008
Location: North Alabama USA
Posts: 103
Angry 5Hp B&S, Weird, hard start, cant control Rpm's

This is a Horizontal shaft 5Hp on my Tiller.
I cleaned the carb, new gaskets n' Diaphram. Clean tank with small rocks and Berrymans. Washed it out good.
It never was good for me.
Always hard to start or started and immediatly quit. Somtimes it would run rich, popping and a bit of blue smoke with each pop. It would quit and restart frequently.
Sometimes the Rpm's would exceed the safety margin and I'd have to kill it.

Finally I took the engine back off and looked it all over again. Your gonna laugh at this next sentence.

When I got it all together again with no noticable improvment, the dang thing was running un-even and popping....as I was watching this I saw the Throttle valve shaft come right up out of the carb and turn around backwards. What the Heck?

Then as I watched and listend the throttle valve popped right up and out of the Carb.

The little screw had vibrated out of the Valve/shaft orfice and the throttle valve went into the intake port.
Look at the wear on the bottom of the Throttle valve shaft!

Its worn almost completly away.

OK, it was a good mystery and I didnt find it till it came apart and waved the pieces at me. A good mechanic would have fixed it before it came apart I'd guess.
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Old 07-04-08, 06:16 PM
hopkinsr2's Avatar
Join Date: Feb 2005
Location: canada
Posts: 1,561
Thanks for the tip. I would never have thought to check the throttle plate screws or shaft, But I'll pay a little more attention now!! Thanks for the help,,,Roger

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