Honda CB 550 Carb Woes…Aftermarket Parts

For those of you who have followed the drama of the great Honda CB 550 carb rebuild of 2011, or if you are joining in because you need to do this yourself, hopefully this will be a somewhat happy ending, to a long, long tale.

I finally got around to pulling the carbs from the bike, once again (this makes approximately 9 times in 2 weeks!), and threw them up on the bench.  Knowing that the carbs were sporadically leaking, from a different carb each time, it was looking like the floats were the issue.  Also, often when this is happening, the float needles can be the culprit, so I needed to get in there and take a look at this as well.

TIP: if you are planning on doing any work to your carbs, often you need to adjust, and then take them apart to adjust again.  Float bowls have round rubber gaskets that seal the bowl to the carb body, and they expand from exposure to gas.  They shrink down to the correct size with a little time in fresh air.  Plan on having 2 sets of gaskets (they are cheap), so that you can swap between the two, not having to wait for the damn things to go back to the right shape.

I cleaned out the slow jets, rinsed the float bowls, and then started to measure the height of the float levels.  On these old carbs, the float height is determined by a small “tang” that pushes against the float needle, telling the carb to stop filling with gas.  If this mechanism is set incorrectly, then gas just flows and flows.  All over the engine, your pant leg, the ground (not very environmental!).  So, let’s get this straight!

Something is amiss with this needle....

While I was in there, I checked out the float needles, and happened to notice that the needle, which sits down into a “needle seat,” was looking like it was down in there too far.  I looked at the other set I had on hand, and low and behold, the other needles didn’t fall in that far.  I posted a question on the SOHC-4 forum, to confirm which was correct, and it turns out the ones I had in there were definitely incorrect.  Swapped the other set in, and had to remeasure the height.  Instantly, it was noticeable that the height was WAY off – based on the new needle seat.  Double checked the height, and put them all back together.

correct needle and seat

Put the carbs back on the bike.  I will say once again, I now know why people might like pods, other than for esthetic reasons.  They make pulling the carbs SO much easier!  But the stock air box on mine makes it a sweaty, dragged out nightmare.  But, I finally got them installed, made sure everything was tight, and it fired right up.  Let it run a bit, checked for leaks, and it seemed perfect.  I was cautiously optimistic that this issue might be resolved, so I turned it on and off again, several times, always looking under the bike for the leaking gas.  Nothing!

I rode it home, and back to the garage again.  Everything seemed pretty good.  Then I rode home at the end of the night, and noticed some real hesitation in the slight throttle position (barely turning throttle – as if in traffic).  I believe that there is crud getting into the carbs from the tank.  Apparently I did not get it as clean as I was hoping to.  I will test it a few more times, and then worst case, I will clean out the tank again, and put some inline filters in.  Hopefully this will take care of any extra rust or debris that is making its way from the tank to the carbs.  Sounds easy, right?

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