Briggs V-Twin has uneven exhaust temps and pops

10216 Views 11 Replies 5 Participants Last post by RideoutKSC, Oct 18, 2013

RideoutKSC

Discussion Starter · Sep 4, 2013

I have a 20hp V-twin Briggs and Stratton that has been giving me problems ever since I bought it as a project back in April.

I have replaced the governor, a gear in the transaxle and most recently rebuilt the carburetor but have had one problem this entire time.

The left cylinder exhaust header glows red. The right cylinder exhaust seems to run cool and pops occasionally. From low to mid throttle the engine runs smooth, but anything otherwise and it pops (from the right side only).

I tried adjusting the valves but nothing changed and I'm not sure if I did it correctly. Assuming I DID adjust the valves correctly, do you think there could be other issues at play here?

Thanks in advance,
Mike

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Bill Kapaun

· #2 · Sep 4, 2013

Some of them have different size carb jets from one cylinder to the next.
Possibly swapped?

Download the IPL for your engine from the Briggs site and see if yours is one of them.

I'dalso examine valve travel to make sure they move the same amount. (flat cam lobe?)
Since you have to remove the valve covers to do this, you might as well look for a blown head gasket.
One at a time, remove one valve cover, have a rag handy and start the engine.
Look for a "mist" blowing out in the gasket area near the push rods.

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Bill Kapaun

· #5 · Sep 4, 2013

When under load, the "good" cylinder has to work harder and will thus run hotter.
I'd expect the "bad" cylinder to run cooler, since proper combustion may not be taking place. I'd expect that to be somewhat variable, depending on how low the compression is.
Between the two?????

Also, if combustion isn't taking place, you may have unburned fuel getting discharged into the exhaust system where it ignites.

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Bill Kapaun

· #9 · Sep 12, 2013

You tore things apart maybe a bit prematurely.
My next suggestion would have been to check the amount of valve travel between the 2 cylinders to check for a bad cam lobe.
Some of these eat cams and you'll get a valve that barely moves.

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