XJ550 Rebuild

I'm sure many of you have seen my posts around here about my 81 xj550 maxim. I've pretty much rebuilt this entire bike now, and i'm about to cut my losses and ditch it.

The carbs are damn near perfect. Cleaned, Float levels set, Cleaned, Synced, new everything, throttle shaft seals, needles, they've been through about 15 times so far. All new gaskets at o-rings. Bench Synced. Everythings stock, air filter, exhaust, no vaccum leaks ect...

Valves are in perfect adjustment. The inside of the engine was spotless. Only has 16,000 miles on it. I did a compression test and it only had about 75-90 psi of compression. Did a leakdown test, valves seal perfect.

So I just did an entire rebuild on the top end. Rings, gaskets, everything. The cylinders were pretty glazed but you still could see the crosshatching, doesn't look like the rings were wore at all. They were still in round. I ran a hone through them and put new rings in. I made sure the rings were put in the correct orientation.

Just put everything back together and the bike started right up. I've had it running for a total of half an hour so far on and off. I'm still having the same problem (and only problem) i've been having for the past 6 months. Erratic and hanging idle. I went and bought a sync stick, and color tune to try and get this bike tuned in. Got the bike close to synced with the sticks, thats when I noticed:

The #4 exhaust is completey cold. Has spark, Pulled plug completely oil fouled. The cylinder isn't firing at all. The rest of the plugs are firing but are pretty black. I'm afraid to take down the road to do the procedure "to seat the rings" when it's only running on 3 cylinders. (And yes I did set the ring gaps correctly, and put the gaps at the correct angles according to the manual)

Anything I can to to see if the rings will seat, or am I up poop creek?

Thanks

 

Are you sure that it's oil fouled and not fuel? They look the same, but taste (I mean smell) different.
When you did the top end did that include the head (specifically replacing the valve stem seals)?

 

Yeah I'm sure its oil, yep new stem seals.

 

Bugger. Have you retorqued the head? Back the nuts off and bring them back up to spec just to make sure the head gasket and o-rings are sealing.

 

that could be #4 cutting in and out. Before you get drastic try a new set of plugs. sometimes you just get a bad one and it drives you nuts

 

Ya. Could be. The oil could just be mist from the rings not being seated yet.