Topic: CB550 carb question

[calal]

I rebuilt the carbs on my '75 550 with new K&L kits - these were the gunkiest carbs I've ever tried to clean and although they turned out well, I figured it might take a couple of tries to get them right.  It starts well (once I figured out the procedure) and I got in a few short rides before it started missing (fully warmed up) at low speed.  By that I mean about 1/4 throttle - crank it open past about 1/2 and it smooths out and pulls well.  I have a perfect rust free tank with a new filter on the petcock.  I'm thinking blocked pilot/low speed jet?  And can I get the jets out without removing the carbs?

Thanks

[Gene]

You can drop the bowls with the carbs on.  You'll need a screwdriver that will fit unless you replaced the bowl screws with allen heads (if you haven't, you should)

[flybox1]

I rebuilt the carbs on my '75 550 with new K&L kits - these were the gunkiest carbs I've ever tried to clean and although they turned out well, I figured it might take a couple of tries to get them right.  It starts well (once I figured out the procedure) and I got in a few short rides before it started missing (fully warmed up) at low speed.  By that I mean about 1/4 throttle - crank it open past about 1/2 and it smooths out and pulls well.  I have a perfect rust free tank with a new filter on the petcock.  I'm thinking blocked pilot/low speed crap aftermarket jets?  And can I get the jets out without removing the carbs?

Thanks

Replace these suspect parts with new OEM Keihin Jets, and only then, complete a clear tube test of your carb bowls (dont trust aftermarket float valve heights) to ensure accurate fuel levels, and then proceed with an idle plug chop on new plugs to dial in your IMS.

[BomberMann650]

Have you tested your ignition condensers?
Missing at low rpm and running strong up high is a sign of that.

[Gene]

Replace these suspect parts with new OEM Keihin Jets, and only then, complete a clear tube test of your carb bowls (dont trust aftermarket float valve heights) to ensure accurate fuel levels, and then proceed with an idle plug chop on new plugs to dial in your IMS.

And this.  Don't scrimp on carb parts.  That's what makes the bike go.

[b52bombardier1]

I just removed all of the aftermarket brass and the float valves from my CB500 carbs because they were junk - sooty spark plugs and leaky overflows.

Replaced it all with better OEM Honda Keihin items and the bike runs vastly better. Yes, this stuff was expensive but the bike was a rolling Molotov Cocktail with a bad miss with the aftermarket items.

All good now.

Rick


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[calal]

Thanks everyone for the suggestions.  I'll look for dirt in the jets first, and proceed from there.  I forgot to mention that the choke lever will mostly cancel the miss, so it's probably not electrical. 

[calal]

I've had good luck with the K&L kits in the past for both carb and petcock rebuilds, but in this case I reused the stock needles to eliminate the variable.