Opposed twin, need some help

[Scrubcadet10]

I've been tinkering with this engine for a few months. Mower has no deck so it's not very important
42A707-2653-E1
Whenever i rev it up high, and the bring it back down to idle, it always tries to or does die, i can bump the throttle up just a hair and it will recover some... i replaced the chinese carb i had on it with a good running OEM used carb... still same issue. Rev it up high, then bring it back down to idle it wants to die.carb is the non adjustable one except for idle speed.
All intake and carb gaskets are new, I've verified that it is running on both cylinders. I'm also wondering, with the engine being 20 years old or so, could it be a valve or valve timing issue?
Spark is good blue on both cylinders, when it idles good it sounds great, and high rpm sounds great...
I'm just wondering if maybe i have the idle set too low perhaps? To my ear it sounds about right... My tachometer stopped working for some reason, need to go buy a new one.
Thanks in advance.

 

[Tinkerer200]

B&S idle recommendations for these engines is high to me BUT if you idle them too slow, lubrication does not reach the top main bearing resulting in wear and the accompanying "chuckle" from the top main when idling. Also, there is a little spring on the back side of the carb throttle shaft arm which may be missing. As you may have seen on another thread you posted on, I can send you a Service Manual IF you like.
Walt Conner
wconner5 at frontier dot com

 

[Scrubcadet10]

I've got a paper service manual from Briggs.
I'll get a new tachometer and set the idle to spec and see what happens...

 

[Scrubcadet10]

I set the RPM up to high end of the spec in my book, 1400.... No problems so far!
Forgot to mention I did get the governor issue worked out, I finally opened the case to have a look see, the governor weights were sitting wide open, and I found a small broke piece of it laying in the sump.. Cleaned and I inspected everything to be sure there was no dents or dings or other metal parts laying around..,so instead of moving with centrifugal force they just did nothing but spin, bought a new one installed and adjusted and it works wonderfully now.

 

[slomo]

Small potatoes but I've see an idle or low speed of 1750rpm. Might try that in the future?? As usual, great job on getting her going.

slomo