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Discussion Starter · #1 ·
A couple months ago my bike was down and not firing on the left cylinder. After troubleshooting a bunch of timing and spark issues, i finally got it to run after spraying some carb cleaner down the intake.
I'm still dealing with problems when I first start my bike in the mornings. It bogs down and dies 4 or five times just pulling out of my driveway. The more throttle I give it makes it bog down even more. I have to very gently feather it to ramp up the rpms before I can engage the clutch and ride away. But after a mile or two of straight riding it seems to run fine for the rest of the day.
I'm guessing I need to pull the carbs off and give them the attention they deserve, but do you think it's necessary to do a complete rebuild?
I've heard from some folks that the internal hard parts don't really wear out. Just to disassemble it, throw it in a bucket of parts cleaner, and put it back together with all new o-rings. Is there any advantage to buying a whole rebuild kit?
I want to order the parts to get this done soon, and I hope to do the job in one shot since this is my daily driver. Would be nice if I could save $50 and just buy new o-rings, but it would be even better to not have to tear into the carbs again. What do you guys think?
It's a 73 CL350

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As for the cleaning I'd do it right (I use an ultrasonic cleaner with carb cleaner). The hard bits I prob wouldn't replace unless they're worn. But new gaskets and o-rings. Meticulous attention to microscopic passages after soaking well. Use a magnifying glass.

Then again, are you using the choke? I have to feather my choke a bit in cooler weather. This swill we get for fuel isn't kind to vintage carbs...
 

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It would help if we knew specifically what bike you're working with.

You might start by syncing the carbs and adjusting the idle mixtures. It really could be that simple. But............................

If that doesn't do it I would get the gaskets/seals and do a thorough cleaning. Some folks prefer ultrasonic cleaning, others like traditional carb solvent. Whatever you choose be very thorough. Other than the ones that move, hard parts do not wear out. Often the hard parts included in kits turn out not to be correct for the application anyway. The brass parts don't have to be shiny, just clean. Ideally one would disassemble and inspect the carbs then order the necessary parts, but it sounds like you prefer not to wait so, I would get a new set of float valves, just considering how old yours probably are.
 

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Discussion Starter · #5 ·
It's a 73 CL350, third gen carbs.
I've synced, and resynced. Messed with the idle mixture a bunch.
I do try to let it warm up, but that usually involves restarting the bike half a dozen times before I just get frustrated and just try to start riding.

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I would ignore the carbs for the moment and check the following in order. Mechanical advance unit may be sticking when cold then as it warms up operates ok. Take it out and clean it then use a small amount of lube on it. Check your points/timing while you are in there preferably with a timing light. Check voltages at the points or preferably at the coils. Does it match battery voltage or within a volt? Now start the engine and watch the voltage, rev the engine what voltage are you seeing? Voltage drops occur at the key switch, kill switch and wiring in the headlight bucket. I have seen these bikes run albeit poorly at less than 6 volts at the points with a battery showing 13 while running.

If that all checks out then check the rubber mounts for the carbs. It would seem you are running lean so when cold there could be air leakage around them. I use a propane bottle with a hose attachment to find leaks.

I would suggest upgrading to the Pamco and better coils.

For cleaning carbs you need to push the brass emulsion tubes out to do a proper clean. There are a couple of very small passages in the emulsion tubes. You need to be able to see light through them not just the holes in the sides of the tubes. Float settings are critical. Use the Honda Gasket kit.
 

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Discussion Starter · #7 ·
I would ignore the carbs for the moment and check the following in order. Mechanical advance unit may be sticking when cold then as it warms up operates ok. Take it out and clean it then use a small amount of lube on it. Check your points/timing while you are in there preferably with a timing light. Check voltages at the points or preferably at the coils. Does it match battery voltage or within a volt? Now start the engine and watch the voltage, rev the engine what voltage are you seeing? Voltage drops occur at the key switch, kill switch and wiring in the headlight bucket. I have seen these bikes run albeit poorly at less than 6 volts at the points with a battery showing 13 while running.

If that all checks out then check the rubber mounts for the carbs. It would seem you are running lean so when cold there could be air leakage around them. I use a propane bottle with a hose attachment to find leaks.

I would suggest upgrading to the Pamco and better coils.

For cleaning carbs you need to push the brass emulsion tubes out to do a proper clean. There are a couple of very small passages in the emulsion tubes. You need to be able to see light through them not just the holes in the sides of the tubes. Float settings are critical. Use the Honda Gasket kit.
Thanks! It seems like everytime I have a plan of action to get my bike running better, it's usually a totally separate issue. I'll break out my multimeter and report back when I get a day off!

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