🏍 CB550f - Cleaned the carbs and replaced sparkplugs, still one pipe is cold

[andrewmundy]

Wanted to ask the collective hive mind for some advice.

Bike was running perfectly until last weekend when I was riding up that big hill up Haight st from Market st and my bike stalled at the very top. Stalls on idle unless throttle is applied. Sounds like a classic blocked carb, right? I clean out the carbs, one of the jets looked not as clear as the rest but other than that looked fine.

Started it up, no dice. One of the pipes still ran cold and stalls on idle. Replaced the spark plugs just in case. Still no dice.

Does my situation sound familiar? I couldn't find anything on the internet. Hoping someone on here might have an idea of what I'm running into.

Thanks in advance!

Andrew

 

[matty]

Do you have spark on that cylinder?

 

[bobl]

Does it run on open throttle on the road? That is does it pull well beyond half throttle, but not idle. If so, it sounds like a blocked pilot jet. If not, check the compression on that cylinder.

 

[augustiron]

Cylinders 1&4 share a point and coil, cyls 2&3 share the other point and coil.
If only 1 of the 4 is misfiring...

It is the carbs (hard to clean properly without the right tools and know how)
Or
the spark plug cap is not attached well to the plug wire ( turn it clockwise to screw it onto the plug wire, it should get tight or bottom out, if not, take it off, trim .5" off the plug wire and reattach)
Or
A bad spark plug


Reading your story again, you have a blocked pilot jet.

 

[shouldnthave]

Sounds like a carb issue. Start by opening the fuel drain on the cold cylinder. That will let you know the float is not clogged/stuck closed. If you have fuel in the carb start the bike and let it run for about 15 seconds. Then pull the plug and see if it’s wet.

If it’s dry, carb issue. If it’s wet, spark issue.

If it’s spark check the wires. If they are original they could use a replacement.

 

[augustiron]

You cant replace the wires on a 550. They are built into the coils.

 

[shouldnthave]

You cant replace the wires on a 550. They are built into the coils.

You’re correct, it’s been awhile since I have fiddled with one. He can cut them back a 1/2” and put on new NGK screw on connectors though.

 

[Maddevill]

When you say you cleaned the jets, I assume you removed the pilot jets and checked them for blockage. Did you also clean the PASSAGES the jet sits in? If you spray contact cleaner in the passage it should come out in the carb throat. Hard to see unless the carbs are off.

Mad

 

[andrewmundy]

Hey guys an update to this. So I finally got it to Ohanlans in SOMA. They found there was no arc on the first plug and the 4th carb had a blocked jet. (Looks like I didnt clean it out well enough!)

Thanks for all your input. Its up and running now!