My Tractor Forum banner

Briggs V-Twin has uneven exhaust temps and pops

10237 Views 11 Replies 5 Participants Last post by  RideoutKSC
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,
1 - 6 of 12 Posts
Thanks Bill!

I actually saw some mist coming from the RIGHT side of the engine when I ran it at full throttle. Would a side-effect of a blown head gasket be popping and a cooler exhaust temperature in that cylinder?
I decided to take the heads off tonight. I found fuel residue in the right side intake took and intake runner on the cylinder head. I think I'll lash the valves and clean the carbon off. Should I do anything else?

By the way, I'll be using this machine to remove snow this winter and tow a dump trailer full of fire wood so I need it running absolute TOPS! Ideas/ Advice appreciated!

Here's what they looked like...

See less See more
UPDATE: The right side cylinder (the one that ran cooler) had a ton of carbon built up around one of the valves. I've spent over an hour cleaning it up and have ordered new cylinder head gaskets.

The valves seem to be sealed nicely, as I could pool cleaner in the combustion chamber while cleaning the heads without any leak down. Do you all have any thoughts on that?
I swapped in new head gaskets and rebuilt the carb. It runs MUCH better with no popping and a nice and even idle speed. I adjusted the valves but did not measure valve travel. I had to chip the carbon off with a wooden chopstick. There is still a difference in exhaust gas temps but it seems to be less of an issue so I'll run a compression test soon. I'm guessing it could be a bad cam since other parts inside the engine were junk when I bought it.
I performed a compression test this morning before work.

Left side = 160
Right side = 120

New Head Gasket and adjusted valves. Looks like I'll measure the valve travel next. I'm thinking possible issues include...

bad valve(s)
bad cam lobe

Am I right? Could there be more?
See less See more
1 - 6 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.