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CV carb question for the more knowledgeable(than me!)

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

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Bringing a KZ440 back from 2 years of sitting in a corner. Did I say KZ?
It's a Suzuki if you squint real hard while looking at the tank badge :lol:, honest. I've got a burble at 1/4 throttle with stock jets. Running rich on right plug so I look deeper. At 1/4 throttle, the slides are bouncing :? . After 1/4 throttle, this ceases and slides open up smooth, winding right up through the RPMs. A whack on the throttle will rev it past the stumble easily, however opening it slowly brings on the stumbling. Any body smarter than me wish to take a shot at a diagnosis? Have done valves, carbs cleaned twice, checked floats, timing, new points&cond, new petcock diaphragm, thoroughly confused :? . Thanks in advance guys(and gals). Bob

I should sell her one of my GS's, huh?
 
check that you don't have a ripped or dryrotted diaphragm in the carb with the bouncing needle
 
DaveO,
Both slides are doing this. Anybody else want to chime in? I know the answer is on this forum. With all the knowledge here WE should rule the world :twisted: :twisted: :lol: Bob
 
Are you getting a good strong spark at low rpms? If your plug wires or caps are bad the bike may run okay at high engine speeds but not at idle.
Axel
 
At very low throttle settings, vacum is minimal. Any kind of variation or leak will be a higher percentage of the overall flow and would prdictably cause the slides to vary noticably.
At higher rpm, it is probably still happning but proportionately minimized so you dont notice it as much.
The only way the slides can "burbble" up and down is if there is an intermittant vacum problem/leak. I would look to either the induction boots (between the carbs and cyl head) or the diaphrams in the carbs, for pinholes or cracks. They can be extremely difficult to see sometimes in either.

Earl
 
The KZ440 was notorious for needing all the vacuum it could get out of the airbox: The air filter has to be in place! If you are seeing the slides, then it sounds like you don't have the air filter in place. We had to tape over half of the inlet hole just to get the things running while the new filter/holder was being ordered. You can also put your hand over the opening to quickly test the difference.
 
the fluttering of the slides at lower rpm's is normal, the slide works off of intake vacume, at low rpm's the vacume pulse cycle is wide enough for the vacume to drop off after the intake valve closes causing the slide to drop back down.

the problem you describe is posibly a bad slide needle, (worn spot, bent) it takes very little wear on a jet and needle to cause transision problems.
also make sure the float levels are exactly the same, cv carbs tend to be very sensitive to the level of fuel in the carb bowls.
 
Let me answer some of the ideas. Intake boots are good, no leaks. Pulled slides and diaphragms, no holes. Needles and slides look almost new with very minimal wear on slides. Floats set to the same height. Had the air cleaner off to figure out exactly what was causing this burble only in one throttle position(1/4). Does the same thing with it on but now I at least know what it's doing, just can't figure out why. Tomorrow I'm going to switch the needles around. If that doesn't do it, I'll switch needle jets then primary mains then secondary mains then pilot jets. Sooner or later I have to move this richness to the left side. At least that way I can remedy 1 problem. Keep em coming! Bob
 
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