make a CV carb not a CV carb

[steven_191]

a KTM's Mikuni BST 40 carb works via a vacuum and isnt directly connected to the throttle.

so as you open the throttle the vacuum created inside the by the opening slide slow itself down from closed to open. effectively less throttle response and also avoids a lean spot as the air increases before the vacuum pulls up more fuel.

im wondering if anyone had dealt with these and converted them to a throttle cable type of operation.

[Kickstart]

Hi

Not sure you can easily. You would need to seal up any vents above the slide, fit a far heavier spring and make a new slide to go down far further and connect to a cable. Then some way of adjusting the idle speed.

Be easier to just get a slide carb, and at least then you could get one with an accelerator pump.

All the best

Keith
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[hmmmnz]

what about the butterfly?
best just buying a flatslide carb

but i suppose it could be done, by drilling and tapping the top of your carb and some how attaching the the cable to the slide
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[Kickstart]

[steven_191]

how big is the need for the accelerator pump?

ive got a 125 2 stroke that doesnt need it? whats the difference?

[stinkwheel]

I've seen it done with an SU carb.

But the person who did it is one of those special people who shit like that seems to work for.

My last MZ had the best of both worlds. It had a 2-1 inlet manifold with a small slide carb and a large CV carb with no pilot circuit. It had a moderately complex throttle linkage that opened the slide carb initially then picked up the CV at 2/3 throttle position.

I would suggest that the effect you are describing is almost purely theoretical though.
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[Kickstart]

[steven_191]

so with no accelerator pump you shouldnt whack open the throttle.

think i might leave the standard system in place then. it obviously works. i have read that widening the holes that allow the pressure change gets you a bit more response. i may try that one day

[Kickstart]

Hi

Yep, with a slide carb when you whack the throttle open wide at low speed the pressure drop through the carb becomes tiny, and it becomes lousy at drawing fuel out of the float bowl.

You can play around with the holes but it shouldn't affect the throttle response as the slide on a CV carb isn't the throttle. The slide is there to control the mixture. Enlarging the holes will change the speed the slide moves, probably making it move faster and having the mixture richer when you crack open the throttle. The strength of the spring determines how far it opens.

All the best

Keith
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