Topic: Help with CB400F Carbs Main Jets and Keyster Rebuilding Kit

[Marty in UT]

Okay, so I've rebuilt a few carbs in my time. But these little Keihins have me confused. I bought four Keyster carb kits off ebay, right. They came with no instructions. Figures. Can't find any instructions online. Great. So what to do? The main thing I can't figure out is the main jets. The jets I pulled out of the carbs each have two small o-rings on them. The main jets that came with the Keyster kits each have one o-ring and one empty groove--and are ever-so-slightly longer than the stock jets (maybe .010" longer). I'm imagining that the end with the o-ring goes in the carb body first, right? When I do this, the groove isn't very close to the carb body at all. The reason I tell you this, is that I was thinking the "extra" o-ring (the small one) that comes in the Keyster kit must go in that empty groove. Well, if I do put that o-ring there, it doesn't look like it's doing any good, as it's not touching anything but the main jet that it's on. And it just seems that the main jets are barely in there, like a few good bumps and they could fall out, which I wouldn't really want to happen, you know. I read on one Web site where sometimes there's a spring to keep the main jets in place. I don't have such springs. And if I did, I can't imagine what they'd clip to. The cylinder the main jets are sliding into is smooth and doesn't have any grooves that a spring could lock into--not that I can see anyway. Can anyone help? I will take some digital pics tonight. Maybe that will help explain my problematic situation.

[cmorgan47]

there should be a small leaf spring that attaches to the bottom of the jet and presses against the bottom of the float bowl....i'm familiar with this as i just put mine back together only to realizes that i'd left all these springs out.  as for the Orings, mine only had the one.

at any rate the sping is part#84 in this diagram, it just hangs off the bottom of the jet.

[supersport_CB400F]

I also only fitted a single O ring, I used Honda parts not Keyster I've read too many bad reports about the quality.

[supersport]

My keyster kits were actually alright, but I also hear that many people complain about them.  I think it is best to keep any Honda parts that aren't actually worn out.  seems to me that the needle, for instance, wouldn't really wear.

regarding the jets, the big spring thing mentioned holds the jet in.  Make sure it points down into the bowl so that it puts tension on the jst.  it only needs one o ring, and that end is the end that is in the carb body.  the other groove is what the big leaf spring type thing rides on. hope that makes sense.