'86 Radian - Cyl1 inconsistent and exhaust clogged. Related?

New to the forum, but not my first vintage resurrection. Currently working on an '86 Radian, but there's no forum just for that so hoping to tap into your collective knowledge.

The bike sat for 10+ years and I've done most of the normal resurrection work, but haven't set the valves yet. Someone was in there because the factory gasket has been supplemented with copper sealer.

The main issue is that cyl1 is not firing (at least not consistently) and all exhaust from cyl2-4 (which are firing fine) is being routed to RH exhaust. LH muffler stay cool, no exhaust coming out. Even the collector exit port leading to the LH muffler is barely warm to the touch after 3-5 minutes of running. Cyl1 appears to be firing a little because pulling the spark plug cap off will cause the revs to drop and then pick back up when replaced.

Is it possible that a blocked connector box or exhaust could cause inconsistent combustion? The pic shows the collector config. Cyl2&3 are joined by a tube, All four cyls going into the common box. It's weird that no exhaust is coming out the LH side. I'll take the cyl1 header and LH exhaust off, but wanted to ask the forum first. Bike is stock exhaust, airbox, everything.

Not my first resurrection project, so already checked obvious things, such as

1. Carbs are ultrasonically clean and bench synced. Diaphragms are fine. Float valve replaced, etc.
   
   
2. Compression decent. My tester doesn't hold pressure, so each cycle measures 60psi then back to zero. I have little doubt it would cycle up to 90+ after a few cycles if the tester didn't have a leak.
   
   
3. Plugs are new and plug#1 is getting spark from coil
   
   
4. Intake manifolds and airbox connectors are new
   
   
5. I have not yet set the valves, which could cause cyl1 to not fire, but doesn't explain why the LH muffler isn't getting hot unless cyl1 is the only one that feeds the left side, which isn't normal.

It might be a sticky float in carb1 due to a slightly bents pin causing flooding, but that wouldn't explain the lack of exhaust through the LH side, assuming the collector box is not a straight pass thru

 

60 psi compression is very low , could be your gauge, Autozone can rent you a gauge. When you do test make sure all the ugs are out and the throttle is wide open and battery fully charged . You might pull the muffler off and see if muffler is open , you might have a restriction blocking system .

 

When I've used the gauge in the past on other bikes the needle would typically not drop back down each engine rev, so the gauge would typically read 60, then 90, then 120 or so. Throttle is wide open, plugs for cyl2-4 were in, but that shouldn't matter for testing #1.

Exhaust coming off today. Tried to get only the LH muffler off yesterday, but a 38 year old exhaust gasket had other ideas.

 

Re-tested compression after cleaning and lubing gauge. All cyls at 140-150 psi

 

Valves checked ... and 7 out of 8 are too tight. The only one in spec (just barely) is Intake4 at .114 (spec is .11-.15). The other intakes are .07-.08 and the exhaust are .09-.14. I still doubt that is causing the problems with #1 since 2-4 are firing fine.

In general, do people follow the service manual for valve clearance specs or do they set them tighter than spec? On most bikes, it's better to be on the loose side, but these clearances seem looser than most.

 

As time passes, valve clearances become tighter. If too tight the valves will not fully close, which is a bad condition! I go for the high side of clearance but it is a fine line.