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runnung rough, cant figure it out
- bone head
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- Skullcrusher
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Bikes: 82 kz750 CSR, 03 Suzuki gsf1200s (stage 2), 73 CB 750 bored to 849, big cam, ports head, big valves, lots of other goodies....
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- TexasKZ
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CV carbs + pods + short straight pipes = nearly impossible to tune for smooth running. Depending on where the pipes are cut, you may have a reversion wave pushing the air / fuel mixture back into the carbs at that rpm.
There are several discussion threads on this forum started buy guys who did the same thing, I do not recall a single one that got their bike to run as well as stock.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
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- punisher11b
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if your dead set on the CV carbs make sure all the rubber in the carbs is good for start. leaking o rings inside the carbs will cause all sorts of problems. check your diaphragms very carefully to make sure they are in good condition as the pod filters will make them more sensitive to external air properties. How do your carb holders look? are they original? The CV carbs can have all sorts of issues with no back pressure. Try stuffing some steel wool in the exhaust to see if there is a major improvement. I know I have seen a few people on here that have mentioned having to do that to fix a bike that had its pipes cut by the PO. if you get a chance throw up a picture of what your working with. most the time I know I'm just scrolling through looking for bike porn :laugh:
I will also second TexasKZ, I haven't been around as long but I have not seen those carbs work better than stock with that setup.
- good luck
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- Nessism
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- SWest
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- 10 22 2014
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Steve
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- Patton
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punisher11b wrote: . . . going with mikuni VM carbs would be much easier. takes no time at all to get them running right.The CV carbs that come with the 440 are so finicky if they haven't been taken care of they can be very expensive/ time consuming to get running correctly even with the stock set up. it's been a year and I'm still tinkering with mine with the air box and all but the VM carb worked good day 1. just a suggestion. . . .
Sounds like a good idea to replace the KZ400/440 stock CV carbs with VM manual slide carbs, especially when the stock air box is unavailable for whatever reason, as the VM's are better at accommodating pod filters than are the CV's.
Wondering which model's VM carbs would be an acceptable choice for fitting as replacements for the stock CV carbs on the KZ400/450? (Thinking ebay possibilities).
Good Fortune!
1973 Z1
KZ900 LTD
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- punisher11b
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I know the VM 34 carbs fit directly into the 440 carb holders. this is where I got mine. fairly reasonable.Patton wrote:
punisher11b wrote: . . . going with mikuni VM carbs would be much easier. takes no time at all to get them running right.The CV carbs that come with the 440 are so finicky if they haven't been taken care of they can be very expensive/ time consuming to get running correctly even with the stock set up. it's been a year and I'm still tinkering with mine with the air box and all but the VM carb worked good day 1. just a suggestion. . . .
Sounds like a good idea to replace the KZ400/440 stock CV carbs with VM manual slide carbs, especially when the stock air box is unavailable for whatever reason, as the VM's are better at accommodating pod filters than are the CV's.
Wondering which model's VM carbs would be an acceptable choice for fitting as replacements for the stock CV carbs on the KZ400/450? (Thinking ebay possibilities).
Good Fortune!
www.amazon.com/Mikuni-Carburetor-Lever-V...uminum/dp/B000GV8QAO
- good luck
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- TexasKZ
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1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
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- Patton
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Seems like 34mm manual slide would be too much carb for KZ400/440, but I have no experience with using any other carbs on the KZ400/440 other than the stock CV carbs.
For example -- using rough figures -- the KZ1000 has four 250cc cylinders, with each 250cc cylinder receiving air/fuel mixture from a 26mm manual slide carb.
It's okay to fit 29mm smoothbore (manual slide) carbs to a KZ1000, but 33mm smoothbores are usually too much carb for a KZ1000 (i.e., a 33mm manual slide carb for each 250cc cylinder).
In comparison, each 200cc or 220cc cylinder on a KZ400/440 would be receiving air/fuel mixture from a 34mm manual slide carb.
At least that's my [possibly screwed-up] thinking at the moment.
Good Fortune!
1973 Z1
KZ900 LTD
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- punisher11b
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- good luck
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- Patton
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At low rpm, such as idle, the signal strength is enhanced by configuration of the slide cutaway design and by having to move through the narrowed bore opening due to lowered position of the slide.
When the carb bore is too large, the signal is weakened because the same suction being supplied from the intake stroke is pulling through a larger opening (i.e., the larger bore).
A common example of coping with a too weak signal at idle rpm or low rpm is when a 29mm smoothbore is readily tuneable at lower throttle slide positions, but a 33mm smoothbore on the same engine proves difficult to tune at lower throttle positions due to an insufficient signal in the larger 33mm bore.
Good Fortune!
1973 Z1
KZ900 LTD
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