I'm having some trouble with my left cylinder not firing, vibration and fuel consumption.
Some history: I bought this '75 XS650 B last August, site unseen (10,000 miles). It sat in a garage for 20+ years with gas and oil and brake fluid in it. Among other things, I totally cleaned the tank of rust and re-lined it with POR-15 tank sealer, rebuilt the carbs (using original main jet needles) & petcocks, replaced fuel and vent hoses, new coils (4.0 Ohm), points, condenser, plugs (NGK LB05EP) and wires (7mm), adjusted valves, gapped points and plugs, adjusted timing (timing light), balanced carbs (manual method-adjusted idle screw on each cylinder to stall, then both equal turns back to 1000 rpm). It kick stared and idled nicely and the plugs are both a chalk brown color, however after 150+ miles of local riding, it no longer starts on first kick and the left cylinder takes 5-10 seconds to fire. After the 5-10 seconds, it idles evenly at 1000 rpm. My first thought is to replace the plugs and re-trim the plug wires. My second thought is the left carb may have flooding / fuel flow problems (float level adjustment, etc.).
It's been 44 years since I had my 1971 XS-1 650, but I don't recall the vibration that this '75 has. 4000 rpm is very smooth, everything else below and above is a bit rough, (rear view mirrors are showing two of everything). I also think the bike is burning through fuel quickly and is slower than my '71 was. At 4000 rpm, I'm going about 52 mph in 4th and 62 mph in 5th. I'll check the fuel consumption over the next few weeks but I would be grateful for any thoughts on these symptoms from you who know the bike and haven't taken a 44 year break. Thanks!