ZBU QUESTION

lenray

Well-known Member
My new to me ZBU---AFTER it runs for a few minutes and also warms up some---The RPMS pick up and it runs way too fast. I can't slow it down--the engine speed. On start up it runs normal. I have to shut it off with the switch to get it to stop running sooooooooo fast.
What do you guys think the problem is?????????

Thank you
 
I think your govenor is wore out. Can you control the rpms by moveing that up and down rod between the carb and the govenor? It is hooked up isn't it?
Brian
 
It doesn't happen every time--when it does REV up I have tried moving those rods with no affect.
 
If you can't control the engine speed by pulling the governor rod that runs from the governor to the carburetor down, then its either:

-sticking in its pivots,-That rod has to move freely, it closes the throttle pretty much by gravity alone.

-rod is too long. (I haven't seen this on a ZB, but have seen it on a U and the governors are similar.-probably due to wear inside the governor.)

-the idle speed screw on the throttle shaft-NOT the mixture screw- is screwed too far in and keeping the carburetor from idling.

-its getting extra air from somewhere else besides the intake, like a worn throttle shaft.

-something worn, or sticking in the governor itself. I have seen a couple that had so much end play in the governor shaft that they could not control the carburetor properly. Also, the pins in the flyweights and the block they push against can wear out.
 

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