V-Twin Briggs exhaust glowing red on one side

I have a project tractor that I've been working on all summer and had a few issues with it.

First: The internal governor was junk so I replaced it.

Second: The transmission was missing a tooth from a gear so I replaced the gear.

My most recent issue involved surging and backfiring exhaust. I took the carb apart and it looked ok. I put it back together and it still surged. I then swapped my fuel pump out with one on my main mower engine. The surging pretty much stopped! Nice huh?

I was just testing out the fuel pump swap (night time) and noticed something interesting. The exhaust on the left side of my v-twin briggs is glowing red and every once in a while a puff of flame comes out of each side of the exhaust.

I sprayed the mating surfaces down with carb cleaner and didn't notice a change in engine idle speed. I had only really run the engine for a couple of minutes without the fan shroud on or an air filter. Could that make the left side glow red?

Any thoughts and recommendations are appreciated.

Mike

it might be that one cyl is getting to much fuel, or something wih the valves are wrong. I havnt really heard of this before so im not shure what its from.

sounds to me like that sides ex valve is letting loose during the power stroke of your motor.. What octane are you running?

I'm running 89 Octane.

I probably need to adjust the valves. This thing was BEAT when I got it.

The popping out of both cyclinders indicates it needs a carb job. The high temp pipe sez you got a valve or cylinder/piston related issue, assuming all the fins are clean and intact and the shrouds are in place.

or you might have a blockage in one side of the intake.

I'm looking up carb kits now. It would be best to replace all of the gaskets and everything.

I just adjusted the valves the best I could. Unfortunately my feeler gauge only goes down to .006" but the specs call for .004" specs. They were adjust well past .006" though, so I adjusted them snug at .006". I took a spark plug out and the left side piston looks NASTY. It is coated in a black sludge.

Everything under the valve covers looks clean.

While this IS really basic, put a new plug in the bad side. There's a small chance that it's failing, and causing your issue.

I swapped the plugs and the bad side is still bad.

Fair enough. How about the wire. You can try running it in the dark of night and watch for arcing. Inspect the insulation, you can even wrap the entire length of wire with a couple layers of electrical tape, paying close attention to where the wire passes sharp metalwork.

Good suggestion.

I adjusted the valves tonight to .005" and no difference.

I also ran a fuel system cleaner through the fuel line and through the carb with no real difference. It seems to idle smoother but the intake burped a few pops while I had it running. I even used carb cleaner and sprayed all of the places where the carb/ intake/ heads meet with no change in idle speed.

The left side is still hot. I'll check for arcing tomorrow evening. I will probably buy a carb kit tomorrow.

Would the exhaust piping make it glow red?? I have even lengths down both sides of my tractor. When I ran the fuel system cleaner through it I saw a couple of pinhole leaks, but nothing major.

I don't imagine the piping is your problem. Any time I have ever seen a manifold or pipe glow on any vehicle, boiled down to raw fuel going into the hot exhaust. At least once, that was because of poor ignition, and another time it was because of a stuck-open fuel injector flooding the bejeezus out of it.

A very lean condition can cause excessive heat, but I just can't picture it making ONE pipe glow on a twin with a single-barrel carb.

Well Doc, I think you just gave me the answer.

I have a double-barrel carburetor!

Okay, BUT- does each barrel feed ONLY one cylinder?

I'm pretty sure. I took the carb apart and it looked pretty clean. I'll have to take it apart again and run a guitar string through the jets and give it a good soak in cleaner.

Each barrel runs to an individual cylinder.

I have completely gone through the carb and it runs nicely now from low to mid idle. The left side STILL runs hot and the right side pops every now and then. I believe the right side has a leak at the header pipe.

The carb has all new gaskets and I used a pipe cleaner through all orifices. I just bought a house in NH and will need this machine to run a snowblower come winter time so I need some help BIG TIME!

It seems to me like fuel is your problem either by passing the valve and going straight into the pipe or its getting to much in the Cyl. at one time causing it to get hot but either way it just sounds like a fuel problem to me

it may be normal.. the kohler command on my walk behind, the muffler always glows. noticeable in the dark. it puffs a bit of flameage when there is no load wide open. i could get a pic or a vid if you'd like

Would this cause the right side to pop and be considerably cooler than the left side?

MCRideout wrote:

Would this cause the right side to pop and be considerably cooler than the left side?

check your valve clearances. you might have a leaking exhaust valve

I tore the cylinder heads off tonight. I figured I already adjusted the valves once and if I need this thing to be tip-top shape I'd better do something big... Are these things carbon'd up? I'll check the valves and such tomorrow or next week.

Here are the results:

I'm guessing the bottom head is the bad side but the top one looks like normal wear to me

Interesting observation. The bottom pic is the right side (the side that runs cooler).

A theory over on mytractorforum is a blown head gasket on the right side. After rebuilding my carb I had a slight mist coming out of the right head area.

Ya I can see that happening a bad head gasket would let more oxygen into the engine thus making a hotter fire and making the exhaust glow red I would just replace it and see what it does

good theory matt, but it would also loose compression, so it wouldnt run for anything. poorly at best..

Good point on the head gasket.. could of been the problem all along..