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Discussion Starter · #1 · (Edited)
Hello all,
I have a Cb360 that continually runs rich enough to foul the plugs. The points and timing are spot on, valves properly adjusted, and the carbs gone through several times. I gave up back in the spring and parked it. Last weekend I disassembled the carbs again, verified all the passages were clear, and checked all the jets and orface tubes. I even pulled out my postal scale and weighed the floats, slides, and slide springs to make sure they were all the same.
The bike has been in the family since new and it has never been rejetted. It came equipped with 100 mains. It also runs the original spec DE8A plugs. I hve checked the floats to ensure they both float (over night) and they have been set at the spec of 18.3 mm. At a loss as how to lean this thing out. I am thinking about adjusting the floats to 20mm and see if that does it. Anyone have any ideas?
To be clear, this is a stock bike with no mods and running factory air filters and David Silver Spares reproduction exhaust. I restored this bike in 2007 and it ran fine for years, compression is in spec and it has less than 1% leak down. I'm wondering if a recent change in ethynol fuel is causing my issue.
 

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Discussion Starter · #3 ·
I have done that. I checked for vacuum leaks with both liquid and propane gas, to no signs of change. It runs great in all ranges and idles fine until the plugs start to foul.
 

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Check the voltage at the points and compare it to the battery voltage. It should be within a volt. Check it at 3000 plus rpm as well.

Check the Ohm reading on the sparkplug caps, make sure there is a good connection.

Pitch the points/condensor and the old coils and put in a Pamco with new coils. Still need to confirm good voltage at coils so check it. Dirty kill switch, poor connections in ignition switch dirty connectors in the headlight.
 

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I had a CB360 that did that same thing, cured it by changing the needles & needle jets. There was enough wear on them to affect the mid-range mixture. Before you spend the bucks for new parts you might try one step hotter plugs, that may help to keep things a little cleaner.
 

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Discussion Starter · #6 ·
Thanks guys, I have been through the ignition. I still run the points but I use a Hondaman transistor ignition and yamaha xs 650 coils. (New wires and caps)I have run the bike both ways, with just points and then with the transistor box connected. Same result both ways. I have had most of the harness hanging off the bike doing voltage drop testing and been through the kill and headlight switch. Nothing .
Mike, the needles and needle jets are still the original, so you might be on to something. I might try going one range hotter with the plug to see what it does first. Do you still have your wing? I have a 77 that I just love. Never thought of myself as a wing owner because the damn thing is more sport than flying leather couch!
 

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Discussion Starter · #7 ·
Update...... I pulled the carbs and reset the floats to 21mm. I did get a pair of one range hotter plugs just in case but I threw in a fresh set of stock plugs and went for a ride. Other than needing to richen the idle circuit up a little, the bike runs great. I put about 30 miles on it and found the plugs much leaner. They still show a little more rich than it probably should be but it's good for now. I'll run a few tanks through it next weekend when I take it up to N.Y. and see where it goes. Thanks for all the help!
 
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