88SS
Active Member
I recently purchased a 1980 cb750f super sport for a very good price. It started and ran ok for a few days, then as I started tinkering it started running lean. The baffles were rotted out so pulled them, then the exhaust, and then replaced it with 4 into 1 exhaust. I tuned up the carbs and it ran ok, but still a touch lean. Condition became worse. Then I changed the plugs, coils, and wires. Replaced the carb boots and did a rejet to 68 and 105. Still lean. Changed the inline filter. Lean. Then my battery starts going dead on me. Changed all the charging parts. The r/r, stator, and rotor.... and the battery cables. I did an oil change, and replaced the k&n filter (in the stock air box) with a stock paper one. Fixed the shift shaft oil seal leak by replacement, and switched to iridium plugs, and replaced the petcock. This is where it gets interesting.
Immediate changes with the new petcock. I'm assuming it was causing most if not all the lean condition. The carbs start pissing gas immediately out of 2 and 4, so I pull them. When I get the bowls off, I notice the ones leaking are adjustable, and the ones not are non adjustable and stock. Long story short, I adjusted them, put them on the bike, and no leakage. Took the bike for a spin and it was like new money. Rode like a dream. No issues for the first time in months.
I talked to the p/o about the carbs, and apparently they are off an 83 model bike and he replaced a couple floats with adjustable. Hopefully my issues with be resolved for a bit, but what should I look into next? I've got a faint tick, so I'm going to tighten the cam chain in the morning. I'm thinking a valve shim wouldn't hurt, but I'm really just looking forward to riding. Anyone ever taken one on a long ride? Any info is good info, and thanks in advance.
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Immediate changes with the new petcock. I'm assuming it was causing most if not all the lean condition. The carbs start pissing gas immediately out of 2 and 4, so I pull them. When I get the bowls off, I notice the ones leaking are adjustable, and the ones not are non adjustable and stock. Long story short, I adjusted them, put them on the bike, and no leakage. Took the bike for a spin and it was like new money. Rode like a dream. No issues for the first time in months.
I talked to the p/o about the carbs, and apparently they are off an 83 model bike and he replaced a couple floats with adjustable. Hopefully my issues with be resolved for a bit, but what should I look into next? I've got a faint tick, so I'm going to tighten the cam chain in the morning. I'm thinking a valve shim wouldn't hurt, but I'm really just looking forward to riding. Anyone ever taken one on a long ride? Any info is good info, and thanks in advance.
Sent from my iPhone using DO THE TON