Briggs V-Twin Rebuild Troubles

[Sdmcarlson]

I have a 44u877-0005-g1 which was in tremendous shape 'cept blew connecting rod #1 - - low oil I guess. So the case was good so I bought a new crank, connecting rod, and 2 sets of new rings and installed. The heads/piston tops were a bit carboned up so I brushed off and cleaned around the valves. Seats looked good. Valve lash set - - Flywheel key good - - Started right up but surged. So, I took off the carb (these have the single barreled carbs that split off) and cleaned. . .runs quite a bit better . . but still kinda rough at speed. When I lower down to idle speeds, it surges. I'm still thinking carb but then see the ends of the exhaust pipes where it goes into the muffler are glowing red. . . . so it makes me think timing. I took off flywheel when doing the crank and installed new key. Valves are set. . . What else is there??? Thanks in advance all.

 

[bertsmobile1]

Check manifold for leaks

 

[Bertrrr]

Sounds like you did a pretty good job on the rebuild - in my experience the timing on these small gas engines is not very tolerant, if they key is not showing any type of sheering it's in time - " unless you missed the cam gear tooth " mis matched with the crank but I seriously doubt it would run at all let alone as good as you describe. As to the exhaust being red - it probably always was but now you're paying it more attention. The surging at idle is not too uncommon I have one that does it all the time but goes away under load.

 

[Hammermechanicman]

When it is surging apply some choke. If it smooths out then problem with idle circuit in the carb or air leak.

 

[Sdmcarlson]

Check manifold for leaks

Thank you!!! I redid the heads with new gaskets . . but I'll check for leaks

 

[Sdmcarlson]

Sounds like you did a pretty good job on the rebuild - in my experience the timing on these small gas engines is not very tolerant, if they key is not showing any type of sheering it's in time - " unless you missed the cam gear tooth " mis matched with the crank but I seriously doubt it would run at all let alone as good as you describe. As to the exhaust being red - it probably always was but now you're paying it more attention. The surging at idle is not too uncommon I have one that does it all the time but goes away under load.

Thanks for the reply. Yeah, I've rebuilt many mowers and if I was off a gear tooth, that will be my last resort to tear apart the engine again. Question for you . . have you ever changed out these V-Twins that have a single barrel carb for a double? I have one and was thinking of trying. . . The intake manifold looks the same and the linkages I believe would work . . .

 

[Sdmcarlson]

When it is surging apply some choke. If it smooths out then problem with idle circuit in the carb or air leak.

That's a good idea - - I saw on a video that the cherry exhaust could be from not getting enough gas - - running too lean. Trying to put together all the symptoms. Carbed heads/pistons, cherry exhaust, runs rough at speed . .

 

[Bertrrr]

I would imagine the machine is matched with a single Barrell carb for a reason / probably balanced for the exhaust ports etc.
Double carb might throw that off and cause you some heartburn but I'm only guessing.

 

[Sdmcarlson]

Sounds like you did a pretty good job on the rebuild - in my experience the timing on these small gas engines is not very tolerant, if they key is not showing any type of sheering it's in time - " unless you missed the cam gear tooth " mis matched with the crank but I seriously doubt it would run at all let alone as good as you describe. As to the exhaust being red - it probably always was but now you're paying it more attention. The surging at idle is not too uncommon I have one that does it all the time but goes away under load.

My biggest fear. . skipping a cam tooth. . . and tearing the engine down again. Low and behold, after cleaning carb really well and having the same issues, I installed a new carb....and that was the issue. Starving for fuel somehow. my thanks

 

[Sdmcarlson]

Yup, it was the carb . .bought a new one and it runs smooth. Thanks all