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Discussion Starter · #1 ·
I recently purchased my first bike a 1974 CB 360. It ran great when I first got it then one cylinder wouldn't fire. I took the carbs apart and cleaned them. I reset the float height and made sure the jets were cleaned out. Both cylinders are now firing and the bike pulls great compared to before. The only problem is that the bike dies when I pull either plug now. Before I got both cylinders firing obviously the side that was firing had no problem when I pulled the opposite side. I dont know how to fix this problem. I am also having smoke come out of my left exhaust on deceleration. I figured that was a air/fuel mixture issue but dont know how to fix that until I solve the dying issue. Any tips help.
 

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Why are you trying to run the bike on one side? if the carbs are not balanced and the bike isn’t fully warmed up yet, its not surprising that the bike dies when pulling a plug. Furthermore, some models need both plugs grounded to to fire (can’t remember if this applies to the 360).
 

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Discussion Starter · #5 ·
I think I may be following the BS on Common Motors lol, But I was under the impression that you needed one cylinder to be firing at a time to correctly get the mixture right. If not then how would I make sure the mixture is correct?
 

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Discussion Starter · #6 ·
So the bike is warmed as I just got back from a good ride. I pulled the plug on the left and it still runs. I pull the plug on the right and it dies. I don't know what is causing this as before I figured it was because my cylinder wasn't firing, but I fixed that issue this week.
 

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I think I may be following the BS on Common Motors lol, But I was under the impression that you needed one cylinder to be firing at a time to correctly get the mixture right. If not then how would I make sure the mixture is correct?
Would you pull 3 plug wires off a carbureted 4 cylinder to get one cylinder idling correctly? If only the numbnuts at Common Motor didn't learn in their backyard and pass that "knowledge" on to those who don't know any better, there would be a lot more twins out there running properly
 

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You probably need to further adjust the idle mixture on the carb feeding the weak cylinder. The owners manual and/or the shop manual gives the correct procedure for adjusting and syncing the carbs.
 

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Discussion Starter · #9 ·
You probably need to further adjust the idle mixture on the carb feeding the weak cylinder. The owners manual and/or the shop manual gives the correct procedure for adjusting and syncing the carbs.
I have followed the shop manual to find the procedure but it no matter what I do it either starts popping or the smoke continues to come out the exhaust when I let off the gas.
 

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I have followed the shop manual to find the procedure but it no matter what I do it either starts popping or the smoke continues to come out the exhaust when I let off the gas.
Did you adjust the float heights according to the CM video? If so, it’s not correct. Otherwise, I’d say there may be something wrong with one of the carbs, especially in the idle or slow speed circuit - something stopped up, something missing or a bad replacement part, something installed wrong, etc.
 

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Discussion Starter · #12 ·
I set it to
Did you adjust the float heights according to the CM video? If so, it’s not correct. Otherwise, I’d say there may be something wrong with one of the carbs, especially in the idle or slow speed circuit - something stopped up, something missing or a bad replacement part, something installed wrong, etc.
I set it to 17mm just the other day, so that might be the issue because the other side was about that high but I just left it as it seemed to run pretty good. Damn!
 

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Discussion Starter · #13 ·
Did you adjust the float heights according to the CM video? If so, it’s not correct. Otherwise, I’d say there may be something wrong with one of the carbs, especially in the idle or slow speed circuit - something stopped up, something missing or a bad replacement part, something installed wrong, etc.
I didn't notice anything missing when I took them apart and all the parts look like what they should look like so hopefully the height does it. Will try that in a bit and let everyone know.
 

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Correct float height for 360 carbs is 19-20. I know the manual says different.

Syncing procedure depends on getting special vacuum adapters, gauges, and a carb adjustment tool.
 

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Discussion Starter · #15 ·
So I reset my float height to the number reccomended in the chat and let the bike run for a bit. It idles nicely at 1200 rpm but still is throwing heavy smoke when I decelerate. I let it run for a good bit then when out and tried adjusting the fuel mixture to a way I heard once. I turned right till I heard the engine about to fall off then back till I heard the engine pick up then set it in the middle of those turns. Can anyone help me with the smoke. I will note smoke is also coming out the breather tube as well, I read that may be an oil issue but I have never touched the oil so nonetheless if you guys reccomend a change of oil I will do that hopefully this week.
 

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What color is the smoke? if the oil is at the correct level (checked when level with the cap not screwed in), isn’t dirty, and doesn’t smell like gas is in it, then I wouldn’t change it. Have you run a compression test on it?
 

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Definitely change the oil, engines tend to last a lot longer with clean oil. Oil contaminated with gas will cause smoking, along with accelerated engine wear. If you've been running it with one dead hole the oil is probably pretty well gas-contaminated by now.
 
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Discussion Starter · #18 ·
I did a compression test on the engines before I got the cylinders working and they seemed fine. I will do another one and change the oil because it cant hurt. The smoke it white/gray.
 

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White smoke usually means water.
 
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