Topic: Will '71 500 carbs work on a '74 550?

[dkruitz]

Looking at a CB550 that needs carb work, am wondering if I can swap in my freshly redone carbs from my '71 500 for immediate gratification? 

[SteveD CB500F]

It'll run, but the innards are different. Different jetting to accommodate the different inlet and exhaust options.

Is it a K or an F?

[Hope]

In 74 only Ks were made.  Has to be a K.

[SteveD CB500F]

Sorry. My ignorance of the US market.

In that case, check the Carb FAQ for the different jet sizes.

As I said, I've run CB550F carbs on a CB500K - it ran OK. (I hope TT doesn't read this  )

[bryanj]

Put the 550 main and pilots in and it wil run reasonably---not perfect but OK

[333]

A great resource is the original Honda Parts Fiche.  This is a good one.  The pictures can be viewed full screen.

http://www.hondaparts-direct.com/fiche_select.asp

The long and short of it is that they each take different carb part numbers.  You'll have to measure to see if they fit.  Or, get the answer from someone who has tried it.  If they do fit, you shouldn't have to change the jets.  The mains are the same, and the slow jets are one size different(38 for the 550 & 40 for the 500), close enough for your instant gratification.

[TwoTired]

freshly redone carbs

What does this mean?   

Cleaned but in stock configuration with stock parts and settings?  Then, then yes it will work but probably tend to run rich, may foul plugs as a 550 sucks harder on the carbs than a 500.

Of course, if you have changed the air filter and exhaust from stock components, you'll have to re-tune any set of carbs on there in order to get best performance.

Then again, if you're staying in the driveway or just doing quick runs around the block like SD, they won't need much tuning anyway. 

Cheers,

[SteveD CB500F]

So true.

I don't go any further than the Ace Cafe nowadays (about 40 miles round trip).

Anything more and I use my modern bike.

[chippyfive50]

im running  71 500 carbs on a  75 550,  jetted up to 105s mains and I THINK 40s (38s were stock?) on the idle, and UNI pods. 
It runs GREAT if the temp is under 90F, it gets a little bubbly (rich) when it hits 95F in the summer, rarely fouls a plug.