GSXR VM29ss Carbs

I'm thinking about installing GSXR Mikuni VM29ss carbs on my kz810.  Anyone use these carbs?  Any opinion, feedback, love/hate etc.  I'm actually quite happy with the CVK32 carbs I'm using now, no complaints really, except that the inlet diameter on the KZ head is 29mm so no point using carbs with bigger throat.  In this repect the gsxr carbs would be perfect size carbs.

Thanks, Nik

diamondnik wrote:

I'm thinking about installing GSXR Mikuni VM29ss carbs on my kz810.  Anyone use these carbs?  Any opinion, feedback, love/hate etc.  I'm actually quite happy with the CVK32 carbs I'm using now, no complaints really, except that the inlet diameter on the KZ head is 29mm so no point using carbs with bigger throat.  In this repect the gsxr carbs would be perfect size carbs.

Thanks, Nik


 

Do you have those carbs already or are you looking for some? I only ask because they are hard to find and so are some replacement parts.

I have run them but the 33 mm version, no issues on my 831cc engine. I did have to respace the bodies on mine and put the cable pull in the center. These carbs come with the cable pull toward the right side so they foul on the bottom of the tank if you don't modify the mount bracket. You also have to watch out for worn slides as they tend to give huge vacuum leaks if there are any scores on them.

Not sure what you have done to your engine besides the bore kit, but you need to know that a flat slide is equal to running a much bigger round slide just from increased CFM. My engine has a big valve pro ported head with big cams, so it can take any carb I throw at it.

Injected, I was hoping you'd reply as I know about your KZ with the TM33 carbs.  I have a line on a set of 29s, thought they are, in reality, 33 with a 29mm venturi.  All gsxr vm29ss had 33mm bodies with 29mm venturi plate.  Anyway, I'm pretty happy with the CVK32 carbs, they work flawless but I'm always looking for something different, I guess.  I've used Mikuni TM two stroke carbs for decades and have lots of needles and jets so I'm familiar with how these work.  I'm curious about how your TM33 responded to tuning and how well they worked after getting dialled in.

My engine is not wild, just wiseco 810 kit with GPZ750A1 cams in Zephyr head with stock valves (on fresh rebuild/maching) and Zephyr Ignition.  Current set-up is very strong and reponsive. 

 

I only have mine because I bought them super cheap years ago, now they are crazy expensive!

I have a set of 29's and the 33's that are on that 650.

I have found that they require quite large pilot jets to run correctly so on my hot rod engine they guzzle the gas. I think I may get around 28 MPG which is terrible but I think that has to do with the rest of the build. The float bowls are slanted so setting up the correct fuel level is quite a chore.

Once dialed in there are no issues, very good throttle response, basically race carbs.

I do have a set of RS34 flat slides to compare with and they work slightly better, maybe because they are new with hardly any wear?

I also have a set of CVK34's on my 750 engine and they seem to perform just as good but that engine is a stock Spectre, basically a GPZ top end with detuned cams (slightly less lift and duration) so its quite a bit weaker than the 831.

The CVK's are the best responding carbs other than the flat slides, way better than round slide VM's excepting the smooth bore series (race carbs) Seeing that your engine is mostly stock I don't think your going to gain much by switching to the 29's over the CVK32's other than the racy look of the GSXR carbs.

I went ahead and bought the GSXR carbs, $300 CDN is not too bad, less than a single TM33 carb!  I'll clean them, look at them and probably put them away with all the other carbs until I need them one day.  I'm very happy with the CVK carbs anyway, and after the expense of new ZR7S intake boots, intake manifolds and Keihin jets I'm not in the mood to mess with a good thing just yet.