Topic: Press-in Jets

[BrickWoll]

Hello all,

I've just begun disassembly of the carbs on my '77 CB550 K3.  I noticed they have press-in jets.  I don't see an obvious way to remove them other than tugging on the brass.  Is this necessary for proper cleaning?  Is it better to leave them in and run a wire through them / ultrasonic clean?  If I've assessed the parts correctly, there is an o-ring in the main jet that needs replacing which makes me lean toward pulling it out.  It sits flush with the body, which doesn't allow for any "grab" area. 

Pouring through carb maintenance manuals, but any practical advice is greatly appreciated.

[Flyin900]

There is only the threaded in main jet into the threaded brass emulsion tube in the center of the carb body, this has the slide needle protruding down into the emulsion tube. The fuel mixture screw on the front of each carb has a tiny O ring and metal washer as part of that circuit. The main brass fuel valve and it's fuel needle assembly needs only to be cleaned and checked for a ring grooved into the rubber V tip.

Just clean it (the slim round slow speed push in jet) in place with your Ultrasonic and some cleaner sprayed directly into the jet. The opening for the passage is in the carb throat, so it is easy to see that the jet is clean.
These jets can be removed, yet it isn't necessary as you noted they are a press fit and likely damage or marking of the outer brass is possible.

IMPORTANT: Honda does not show them as a part on the Honda parts fiche at all, so it's hard to figure it out. They are a #42 size and JetsRus has the correct Keihin jet part if needed.

[BrickWoll]

Just clean it in place with your Ultrasonic and some cleaner sprayed directly into the jet. The opening for the passage is in the carb throat, so it is easy to see that the jet is clean.
These jets can be removed, yet it isn't necessary as you noted they are a press fit and likely damage or marking of the outer brass is possible.

Honda does not show them as a part on the Honda parts fiche at all, so it's hard to figure it out. They are a #42 size and JetsRus has the correct Keihin jet part if needed.

Thanks for the response.  It eliminates the risk of damage to just clean them in place, so that's the plan.

[brewsky]

The pressed in slow jets can be removed by sliding a short section of reinforced fuel line over the jet and using vice grips, (or parallel-jaw pliers), to prevent damage to the outside of the brass.

Pull and twist, but don't "rock" the jets.

Removal is the only way to make sure they are clean.

[bryanj]

From experience they need to come out to clean the body passage, Sirius in Canada do pattern ones. refit with a light tap of a nylon hammer

[DaveBarbier]

Agreed. Pull the jets. Not hard to do as described above.

If you don’t and you experience bogging or stumbling once the bike is all together you’ll kick yourself that you didn’t take the time to clean them more thoroughly. These jets have cross drilled holes that clog easily which can’t be cleaned by a wire if the jets are in place. Ultrasonic cleaning might get them but you can’t be sure.

[BrickWoll]

Thanks everyone.  I did actually try the method of using a gas line and pliers to pull the slow jet.  I stopped when the force required seemed excessive for such a delicate piece.  Just going to take more power, I guess!

[Mainebikes1]

I have a commercial-grade, American-made ultrasonic cleaner and for many years have cleaned carbs as a sideline/ hobby... You really do need to pull them to properly clear the passageways. Even with the ultrasonic process, the passageways need to be open to allow the contaminants to be removed. The pics attached show a rack from an ‘80 CB650. The pic showing 2 of the 4 dirty slow jets shows how they looked “after” the rack was ultrasonically cleaned but WITH those slow jets still in place in the carbs.  The clean jets pic shows the same 2 jets after they were pulled out and ultrasonically cleaned. It illustrates why you do need to pull them, to be absolutely certain they are not clogged...

 They will indeed come out; Try a little PB Blaster or similar and let it sit for a few minutes., I also find that a few short bursts with a heat gun on the jet body towers help free them. Gently twist in a circular motion while pulling and they will come out. And a pair of pliers typically won’t give you enough grip; small needle-nose vise grips work well. If you find the vise grips slipping off the protective fuel hose, incrementally tighten the vise grips until they grip. The jets will come out eventually, really isn’t that difficult. Most of the resistance you feel is just the result of a bit of normal corrosion stiction from age; if that rack was brand new those jets would come out with very little fight...

[BrickWoll]

I have a commercial-grade, American-made ultrasonic cleaner and for many years have cleaned carbs as a sideline/ hobby... You really do need to pull them to properly clear the passageways. Even with the ultrasonic process, the passageways need to be open to allow the contaminants to be removed. The pics attached show a rack from an ‘80 CB650. The pic showing 2 of the 4 dirty slow jets shows how they looked “after” the rack was ultrasonically cleaned but WITH those slow jets still in place in the carbs.  The clean jets pic shows the same 2 jets after they were pulled out and ultrasonically cleaned. It illustrates why you do need to pull them, to be absolutely certain they are not clogged...

 They will indeed come out; Try a little PB Blaster or similar and let it sit for a few minutes., I also find that a few short bursts with a heat gun on the jet body towers help free them. Gently twist in a circular motion while pulling and they will come out. And a pair of pliers typically won’t give you enough grip; small needle-nose vise grips work well. If you find the vise grips slipping off the protective fuel hose, incrementally tighten the vise grips until they grip. The jets will come out eventually, really isn’t that difficult. Most of the resistance you feel is just the result of a bit of normal corrosion stiction from age; if that rack was brand new those jets would come out with very little fight...

Thank you for this.  Going to pull them.  It makes sense that the reason they are not coming out with moderate force is because they are likely corroded and need cleaning.