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Re: [Shop-talk] mower engine issue

To: shoptalk <>
Subject: Re: [Shop-talk] mower engine issue
From: Battmain <>
Date: Tue, 25 Aug 2009 05:57:52 -0700 (PDT)
On the engine itself, find the model number, usually stamped somewhere
on the muffler or close to it. Google the model number for the parts list. 
Depending on how handy you are, you can take the carb apart, the bowl
portion, and replace the needle valve seat and the needle valve itself. That 
will help fix the mixture problem. The oscillation is caused by mixture 
fluctuations. As mentioned, the spring is connected to the governer.
Usually it is just a secondary flap in the air intake. When you remove the
carb assembly, you can see how it works. It is possible to temporarily 
bypass it for testing, but monitor the throttle slider as you can overspeed 
the engine. I've had multiple small engines with this issue and replacing 
the carb parts resolved the oscillation problem. On a few, when I was 
lazy I zip tied the governor so I could get stuff done.



----- Original Message ----
From: "" <>
To: shop-talk@Autox.Team.Net
Sent: Tuesday, August 25, 2009 7:50:15 AM
Subject: [Shop-talk] mower engine issue

so it starts and runs...but it runs with an 'oscillation', I guess is how I'd 
describe it. if you hold the throttle pedal down, it won't maintain a steady 
rpm. up and down at a fairly frequent pattern. there's an actuating rod 
attached to what I think is the throttle plate in the carb (there are two 
butterfly plates in the carb--the choke and the plate to which this rod is 
attached). this rod runs under the gas tank and is attached to the motor in 
some fashion (can't seem and wouldn't understand it anyway, so didn't remove 
the tank). this rod is moving back and forth at the same periodicity as the 
engine rpm oscillation. clearly, that's what's causing it. 

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