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Carb issues '79 LTD kz400
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30 Jun 2014 12:30 #638468
by RiderRandy
79 Kz400 Ltd.
Carb issues '79 LTD kz400 was created by RiderRandy
Hi everybody,
This a 1979, KZ400 LTD, almost entirely stock. Original carbs, have already been cleaned once, blocked off the vacuum for the petcock. I have half of the original air box, the part that attaches to the carbs. I do not have the part that holds the air element, however I have fabricated a piece that is similar and holds a filter.
I got it to run fine after a cleaning, with no air filter (half the box), and the choke on(butterfly's closed). This was good for cruising around, but I want to run with no choke. With the air box that I made, it restricted things, and I have little or no power, with the choke on. I forget to see if it ran better with the choke off before I pulled the carbs again.
Currently the carbs are back off, and I am wondering if I should be looking out for something specific before I put them back on.
The problem is this, The bike starts and runs with a really high idle 3k-4k rpm, with the choke off (butterfly's open)(half an air box). If I turn the choke on (butterfly's closed), I got a nice idle at about 1k-2k, depending on the idle screw(again half an air box).
The only other problem is, when I rev it up and let go of the throttle, on its way down (decelerating) it will drop below 1k rpm and die, which means I would have to keep rolling the throttle, but eventually I can let go and it will idle. What I mean is, I cannot just let go of the throttle or it will die, but if I roll it a little it will stay running on its own.
I can provide pictures here shorty, so you know which carbs I have exactly.
Whats up with that?
If a local could help me out, I am in California Bay Area, in between Berkeley and Walnut Creek.
Thanks,
RR
This a 1979, KZ400 LTD, almost entirely stock. Original carbs, have already been cleaned once, blocked off the vacuum for the petcock. I have half of the original air box, the part that attaches to the carbs. I do not have the part that holds the air element, however I have fabricated a piece that is similar and holds a filter.
I got it to run fine after a cleaning, with no air filter (half the box), and the choke on(butterfly's closed). This was good for cruising around, but I want to run with no choke. With the air box that I made, it restricted things, and I have little or no power, with the choke on. I forget to see if it ran better with the choke off before I pulled the carbs again.
Currently the carbs are back off, and I am wondering if I should be looking out for something specific before I put them back on.
The problem is this, The bike starts and runs with a really high idle 3k-4k rpm, with the choke off (butterfly's open)(half an air box). If I turn the choke on (butterfly's closed), I got a nice idle at about 1k-2k, depending on the idle screw(again half an air box).
The only other problem is, when I rev it up and let go of the throttle, on its way down (decelerating) it will drop below 1k rpm and die, which means I would have to keep rolling the throttle, but eventually I can let go and it will idle. What I mean is, I cannot just let go of the throttle or it will die, but if I roll it a little it will stay running on its own.
I can provide pictures here shorty, so you know which carbs I have exactly.
Whats up with that?
If a local could help me out, I am in California Bay Area, in between Berkeley and Walnut Creek.
Thanks,
RR
79 Kz400 Ltd.
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30 Jun 2014 14:07 - 30 Jun 2014 14:08 #638480
by RiderRandy
79 Kz400 Ltd.
Replied by RiderRandy on topic Carb issues '79 LTD kz400
:huh:
What is that missing hose for? I could JB weld another hose on there?
Fixed that gap.
Now that I have played with the idle screw on the bench, I can tell you that it was almost all the way out, so perhaps that explains the high idle. I ran it all the way in, visually confirmed the butterfly's are closed, then twisted two and a half turns out, which revealed a small gap.
Might just put em back on with the air box and try it.
Attachment Carbs.jpg not found
What is that missing hose for? I could JB weld another hose on there?
Attachment carbs2.jpg not found
Fixed that gap.
Now that I have played with the idle screw on the bench, I can tell you that it was almost all the way out, so perhaps that explains the high idle. I ran it all the way in, visually confirmed the butterfly's are closed, then twisted two and a half turns out, which revealed a small gap.
Might just put em back on with the air box and try it.
79 Kz400 Ltd.
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Last edit: 30 Jun 2014 14:08 by RiderRandy.
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