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Offline Bastaldo

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Cb550 no start
« on: August 11, 2020, 09:30:12 AM »
Hi everyone- I’m trouble shooting this bike again. 76 CB550.

New topend rebuild, rebuilt carbs and jets, new electric, new battery, rebuilt gas cap vent, new gapped plugs.

However, I just can’t get he bike started easily (kick only) and if I do, it’s running rough and/or not firing on all cylinders. I want to say the 1 and 2 tend to not fire. 

I’ve pulled the carbs and cleaned the (new) jets a bunch of times (and again right now). I’ve measured out the floats and they are correct re the book. The bowels are filling with gas, although the plugs don’t seem be getting wet. I’ve in-line tested the coils/ignition wires/ plug boots and they are all good. 

Prior, it was running fine and then would just die on the rd- and sounded* like it was starving for gas.

Out of the gas, fire and air, I’m not sure what’s going on here. I believe it’s the carbs but not sure how/what   Any thoughts?
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Offline calj737

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Re: Cb550 no start
« Reply #1 on: August 11, 2020, 09:56:54 AM »
confirm your spark plug wires are correctly connected to the proper cylinder/coil pairs. one coil runs 1/4 and the other 2/3. Common mistake
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Offline Smudgemo

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Re: Cb550 no start
« Reply #2 on: August 11, 2020, 10:18:51 AM »
Is the battery good?  Mine was going bad and I didn't know until it was struggling to do much of anything.  New battery and suddenly the bike ran properly.  Seemed like an early demise so I didn't suspect anything.
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Thread - How to fix your starter button (for real): http://forums.sohc4.net/index.php/topic,163170.0.html

Offline 123 Four

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Re: Cb550 no start
« Reply #3 on: August 11, 2020, 10:40:19 AM »
Quote from: Smudgemo on August 11, 2020, 10:18:51 AM
Is the battery good?  Mine was going bad and I didn't know until it was struggling to do much of anything.  New battery and suddenly the bike ran properly.  Seemed like an early demise so I didn't suspect anything.
Hi,
About a month ago a had a similar issue with my 1976 cb 550 f. Mine won‘t start, cylinder 1 and 2 were fine, 3 and 4 were not firing all the time, bike was starving for fuel and was only idling with choke on.
I have cleaned the carbs many times and have checked for air leaks at the rubber boots. Nothing was wrong with that...
I rewired the fuel lines. They need to have 5.5 mm lines (mine were only 5mm) and the front one from the petcock need to be connected to carb 3+4 and the back one need to be connected with carb 1+2.
Plus i filled the tank with 98 octane gas.
My bike is running fine now, no problem with gas any more...
So maybe check your fuel lines for correct size, length and wiring?
« Last Edit: August 13, 2020, 07:41:15 AM by 123 Four »
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