31 HP Vanguard V-twin missing

[G Archer]

Hi everyone ,I have a B&S Vanguard Model# 543477 Type # 0114-e1 Code # 05070612 that is giving me fits.I rebuilt with new rings,gaskets,seals,relapped valves.The engine cranks fine but only seems to have power on #2 cyl.Both sides have good spark(checked with spark tester while running).Changed plugs no change.Each cylinder will run on its own.Temp on #2 cyl exhaust is 500-600 degrees but #1 cyl is 300 degrees. Valves are set at .005.Seems to me a valve is not seating.What am I missing? Thanks for any help. Glenn

[RoyM]

I #1 getting adequate fuel? There could be a problem in the carburetor or with a downstream intake leak. The main jets are different for each cylinder. Did you reverse them?

[bgsengine]

Also have you swapped the coils side to side and inspected the diode harness (if it has one) - some of those V-Twins are known for the diode failures in the ground harness

[G Archer]

Thanks for the replies.I will check the carb.If the kill harness was bad would it have good spark? Spark will jump a 3/8 gap.

Thanks, Glenn

[bgsengine]

2 things - try new plugs or swapping plugs and see if the problem moves - and if the kill harness was failing - it might not be firing one cylinder under compression a leaking diode may offer less resistance than the secondary on that side and then the circuit would ground through the other coil's primary.

[KE4AVB]

It would not hurt to also check the valve lift while your at it as a worn cam lobe can cause delayed valve opening/closing resulting lost of power especially when the valve clearance are set properly.

Also if your haven't rebuilt the carb check those main jets as they do tend to become lose as their retaining o-rings shrink. If this is the case then one cylinder could be running rich especially when not loaded as these Nikki tend to run off the idle mixture. This would let lose mains to leak surplus fuel but they tend to seal off under load as the jets are suck up against their mounts.

Just thunking out loud...

[G Archer]

Thanks for all the great replies folks.I took the carb apart and cleaned it put it back together and it runs like a top.It was fairley clean but must have been just enough.Thanks for all your help



Glenn

[KE4AVB]

Thanks for letting us know you got it working.

As for looking clean I had one Nikki Twin last year that I cleaned after the customer had reversed his fuel filter.It was still giving problems even after I cleaned it. It appeared spotless but in the one of the idle jets was what I assumed was a grain of sand. Thought I was never going get it out such a tiny metering hole.