78 KZ650 What are these carbs?

I just went through same and set them 1 1/2 turns on each. If I had researched it more I may have put the 24ss on mine. They got tossed on ebay as I grabbed a more familiar set out of the boxes of parts I got with the bike. Good luck with it, sounds like a nice bike.

jdvorchak wrote: thank you sir!
Now he asked about pods and I said I'd check on the forum to get the popular consensus. I have lots of experience with CV carbs and virtually none with these. I'm checking on pricing for the air box boots and comparing that to K&N or other quality PODS. My initial thought is stick with OEM air box. But I said I'd ask here.

DynoJet jet kit part no. 2306, $139.99

Try it Ed you might like it.


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Fortunately, I doubt I'll ever need to try it. In the past 40 years I've put more than 60,000 miles on my 1977 KZ650-C1, and I have never needed to even think about replacing any of the metal parts. I've replaced the carb bowl gaskets and the cap gaskets once when I had to clean the carbs after letting them sit unused for months with fuel in them (really dumb on my part). Other than that and performing a dynamic sync they have needed no attention at all. That's probably why I'm always puzzled when I read about folks rebuilding their carbs. Maybe I've been really lucky or maybe it's because the carbs on my bike are not the CV type, don't have accelerator pumps, etc. Thankfully, there's really not much in mine that can wear out. Ed

If people would ride the bikes, other than fill the fuel tank and change the oil, there is not much to do. I have two KZ's in my garage right now that have sat for years. Tanks are dirty. Oil is dirty. Carbs are dirty and old gas clogs them up, as you well know. I say "rebuild" but really all I ever do is clean and tune the carbs mostly. I can think of only one or two instances where I've had to replace parts other than O-Rings and hoses out of the dozens of carbs I "refurbish" every year. I don't understand the need some folks have of replacing internal carb parts like jets. I have yet to see a jet that I can't thoroughly clean and put back in service.

CV or smooth bore? No difference in robustness. Actually when you flip them over it's hard to tell if you're working on a smooth or CV. Let the bike sit and you will be pulling the carbs.

Update. I cleaned up the carbs and adjusted the floats. The #4 intake boot was loose! Cleaned it up and checked for leaks then put it back. I was able to salvage all of the air box boots by soaking them in Wintergreen Oil and Xylene. If you haven't tried that you should as it works amazingly.

Put it all back on the bike and tried to test start and warm it up for carb sync. Well darn. It still ran like crap. Could not get it to idle but choke did seem to help... a little. With the sync gauges hooked up the best I could see was about 4 inches of vacuum. Way too low. So I took off the points cover. Yes it still has points ignition. Hooked up my test light and all 4 cylinders timing was way retarded. I mean not even on the scale. I'm surprised it actually started after seeing that. So I static set the timing. That did the trick. Starts instantly with no choke, takes the throttle well and idles smooth as silk. I only had to touch up two carbs sync to get perfect. But honestly my bench sync was within 2 inches.

One final thought. For the new guys, when the old timers here tell you to set the valves and timing before even messing with the carbs, there is a reason. Had I been less experienced and not confident with my carb skills I'd have been pulling the carbs again to see where I messed up.

Now you say "Why didn't you do that in the first place?" Well one of the carbs was leaking fuel. Turned out it was a crack in the overflow pipe which I soldered. The air box boots were no longer fitting on the carb intakes and I could see that #4 intake was loose. I was told the bike had been sitting for over a year, maybe two. So I had every reason to pull the carbs and go through them. In so doing I also found 1 partially clogged idle jet and one completely clogged idle jet. All of the enrichener circuits were also clogged and there was rust in #3 and #4 float bowls. All 4 pilot jet plugs had cracked O-rings. All of the floats were at different heights and none were even close to the correct 23 mm recommended preset. All of the mixture screws were adjusted way too far out.

When you buy an old bike that has been sitting there are procedures, the experts on this forum, suggest and there is a reason for that. Unless the bike is completely tuned up, valves, cam chain tensioner etc. You can't reasonably expect good results. Sorry there are no shortcuts.