On Fri, 23 Feb 2018 13:18:04 -0600, Terry Coombs
wrote:

On 2/23/2018 11:43 AM, ultred ragnusen wrote:
What mostly makes a small simple engine (such as the Honda GC 160 that runs
my pressure washer or the Honda engine that runs my lawnmower) "wheeze"
fast & slow, fast & slow, fast & slow while idling under no load?

* snipperoo

I'm asking about the physical reason for the idle speed varying cyclically.

* It's called surging , and it's caused most often by clogged fuel
passages in the idle circuit or an improperly adjusted idle mixture
screw . But mostly the former . .


Almost definitely a lean surge - caused by either varnish or
"greenies" in the jets.

Get some SeaFoam. Drain the gas. Refill with fresh (preferably ethanol
free, but I realize that is a problem for some) and SeaFoam according
to the instructions on the can. start and run on part choke for about
5 minutes. Let sit for a couple hours and restart. If still surging
run on part choke for another few minutes and let it sit again. Then
run the heck out of it to run the tank of fuel; though it and see what
happens. This will fix varnish issues virtually every time - and will
often solve "greenies" as well. Bad "greenies" will require
dissassembling the carb and poking and blowing the jets clear. A bit
of Seafoam in each tank will prevent greenies or varnish. Do not store
long-term with ethanol gas - even with Stabil (Or Sea-Foam) in the gas