I have a 1975 Honda CL360, and apparently I'm an idiot. Because I cannot figure out what's wrong with this bike. I'm relatively new to motorcycles repair, but still I feel like all the bases have been covered. I told myself I would not go on reddit to make my incompetence someone else's problem, but here we are 🤷♂️.
The bike: 1975 Honda CL 360. Mikuni VM30 carburetors with pod filters. #35 pilot #145 mains. Antigravity 801 lithium battery (new-ish). Custom tank, probably off a 1968 Honda CL125.
The situation: It starts immediately with choke off. If i put the choke on, it revs out of control. It idles high, about 2000rpm. The idle is VERY rough. The right cylinder is lazy. Pulling the spark plug wire off it barely affects RPM. I've messed with the air screw tons, I can't find an adjustment that makes it actually contribute. I've tried new plugs. The ignition timing is near spot on (within a half mm of perfect). The compression is 145 in both cylinders. I have pulled the carbs apart and cleaned several times. I have checked for air leaks with carb cleaner multiple times. I have purchased a vacuum sync tool: the left (strong) cylinder pulls 5cmHg, and the right (weak) pulls almost nothing (maybe 1cmHg? 0?). I checked the timing again, still fine. I checked for leaks with carb cleaner, still doesn't seem like there is one.
The plugs are black and smell like fuel. The exhaust is dark and sooty. The engine oil has no metal shavings in it.
Should I re-jet the pilots? The previous owner said she had it running great with the #35's before letting it sit for a year or so. So I don't understand why it would need different jet size now. And would that even explain why the vacuum sucks?
Something with the valves? I've heard the cam chain tensioner in these tends to go?
The tank is custom and has dual petcocks - could I be over-delivering fuel to the carbs and drowning things somehow? Even though the float height seems right?
Please help I'm so sick of trying to fix it instead of riding it.