Topic: Clean your pressed in slow jets!

[pwright]

I picked up a '78 550k a couple weeks ago, and subsequently rebuilt the carbs. The internals were very clean, and because of this, I made the decision to forego pulling out the slow jets to clean them. I sprayed a lot of carb cleaner through them, as well as compressed air, and it came out the other side fine which I thought indicated that they were clear. Well, I got it running a couple nights ago, and it ran like crap... so yesterday I got the carbs back off (in 15 minutes, nonetheless... I'm getting very quick at it) and pulled the slow jets. I marred the sides of them pretty good, but they came out with a little work.

Two of the slow jets were partially clogged. Surprisingly, the emulsion tubes were totally clean... just a partial blockage in the jet orifice even though I had been able to get a thin wire through them previously. Cleaned 'em back up, put the carbs on... and it started right up and idled like a dream!

I think TwoTired has mentioned a bunch of times to assume nothing when it comes to the slows... and I wish I'd taken his advice the first time around... hopefully others will learn from this mistake.

[anparkinson]

I had exactly the same problem with mine - they should be 0.42mm so I got a 0.40mm model drill and redrilled them to a loose fit. Loads of white powder came out. The bike runs perfectly now.

[Tim.]

Your slow jets push in?  My '76 CB550F has threaded slow jets.  Frankly, for the $4 each or whatever they cost, I think I'd buy new ones if mine were so bunged up I needed to drill them.

[pwright]

Hey TinTin,

Yeah, they are the pressed in type... I think I read on here where Honda was trying to appease the EPA or something like that (don't remember the whole story), and went to pressed in jets in later models so that people couldn't fool with the jetting so easily..?? ... real bummer as the threaded ones are nice indeed. The mains are threaded and took no time at all to clean...

[Tim.]

Yeah, now I remember that - I don't think the slow jets are even supposed to be removable, so no wonder you had to wrench on them a bit.  Funny thing is the mains in mine are 'pressed' in with an o-ring (which doesn't like carb cleaner of course).  There is a leafspring that pushes between the main jet and the carb bowl, keeping the main from dropping out.  Funny that they'd thread in the slow jet but then go that route for the mains.