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slide carbs or cv carbs?

Agemax

Agemax

Forum Guru
opinions please on which ones are the best. which gives the best performance and are easier to tweak? which ones are easier to tune to uprated motors?
i have a 78 gs1000 with a wiseco 1085 big bore and a harris race 4 into 1 currently running slide carbs but have the chance of a set of cv's..................do i or dont i ?
 
VM slide carbs are easy to tweak, quick throttle response.
CVs, better at compensating for changes in altitude, may give more power wide open, as the bore is bigger, but you need to swap heads, the intakes are bigger for these carbs.
 
CVs aren't all that hard to tweak, either, but as tkent said, you will have to change your head to match the increase in intake size.

The VM (slide) carbs have a more-instant response to throttle input, but possibly at the expense of driveability. All carbs rely on air movement to draw fuel through the jets. That air movement is because of the vacuum formed by the pistons and the restriction of the throttle plate. When the VM carbs are opened suddenly, that vacuum disappears, causing a momentary lack of acceleration. This can be minimized by opening the throttle a bit slower or finding a set of carbs with an accelerator pump.

The CV carbs minimize that lag by using a slide that is controlled by vacuum. When properly set up, the slide responds to the vacuum in the intakes, and lifts to allow more air. This smoother operation is better-suited for street use by maintaining Constant Velocity across the jets.

CV carbs have been around for a while, but really came into use when the EPA started demanding better emissions from motorcycles. Because their operation was more predictable on the street, virtually all manufacturers adopted them.

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Now there's an argument that could last all night but I won't be drawn in to a critique of the different types of carbs.

As tkent02 says, you would have to change heads or get some Sudco adaptors (never tried 'em) to make CVs fit your bike and you won't get the bang you're looking for.

I presume your bike is UK spec and fitted with VM28s. You could try VM29s / 33s etc and that might work well with the 1085 kit. They won't be cheap though.
 
cheers guys. was just a thought but sounds too much like hard work. will keep my eyes peeled for a set of 33's i think.
 
33s' are going to be the hardest to "tweak" in.

CV are the best street type for the smoothness thru the pilot transition.


all slide carbs have flat spots and many quirks .
 
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