KZ440's with Mikuni VM carbs

  • Dbrown4k
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KZ440's with Mikuni VM carbs

24 Oct 2024 14:24
#905413
So I’m very new to this forum as well as motorcycles but I’ve been getting a ton of info on here. I was also looking to do a single carb conversion and came across another thread on here detailing how the guy did it on his 440 with a custom manifold and vm34. I’d link it on here but I don’t know how. The original carbs on mine are cv 36. My question is isn’t that bigger than a mikuni vm34 especially since it’s two of them? Thanks for the help

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  • TexasKZ
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Re: KZ440's with Mikuni VM carbs

26 Oct 2024 13:00
#905484
Yes, 36 is larger than 34. However, as a rule, mechanical slide carbs, like the VM series, flow noticeably more than a similar sized CV ( constant velocity) style carb. On a twin cylinder bike, only one cylinder at a time draws in fuel, so the engine could not draw enough to make a CV72 even work at all.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
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Re: KZ440's with Mikuni VM carbs

26 Oct 2024 13:04
#905485
P.S. Are you considering this modification? If so, I recommend finding some threads that ended with success.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24

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Re: KZ440's with Mikuni VM carbs

26 Oct 2024 13:36
#905491
Hey just to add some more to the topic here is a quote from a book I found in the Seattle Lib system many years ago, Motorcycle tuning by John Robinson for what ever that is worth. 

"For the same sections area a slide carb flows more than a CV carb by some 20% or more. A smooth bore flows about 5% more than same size slide carb.  A flat slide has better air flow under it edge at part-throttle allowing better control of part-throttle carburation and better pick up. Smooth bore - with a min of steps and surface irregularites are also more receptive to pulse tuning in the intake and will show larger increases in air flow when intake length is resonant with engine frequency".
 
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Re: KZ440's with Mikuni VM carbs

26 Oct 2024 18:20
#905501
I don't know what it is with the twin guys, but they don't like to rebuild carbs like the rest of us.  There are lots of threads where guys dump serious $ into Murry carbs, or VM conversion kits. And many struggle thereafter.   While the thought of a new carb is alluring, these old Mikuni and Keihin carbs are very easy to work on, and fixing the stock setup is the path of least resistance in most cases.
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Re: KZ440's with Mikuni VM carbs

27 Oct 2024 11:35
#905516
I don't know what it is with the twin guys, but they don't like to rebuild carbs like the rest of us.  There are lots of threads where guys dump serious $ into Murry carbs, or VM conversion kits. And many struggle thereafter.   While the thought of a new carb is alluring, these old Mikuni and Keihin carbs are very easy to work on, and fixing the stock setup is the path of least resistance in most cases.
Amen!
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24

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Re: KZ440's with Mikuni VM carbs

27 Oct 2024 12:33
#905518
There was also a guy a while back that put a set of Chinese knockoff 36VM's on a KZ400 engine. I remember they ran just fine, but they had oddball threads on the jets!
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
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