modifyng BS34 CV carb slides

I read a thread that talked about the problems in running pods on CV carbs which detailed the issue of lower vacuum in the carb without a stock air box. This is my take. The free flow of air causes the slides to not raise as much (since they operate on vacuum) which in turn causes poor midrange performance. One remedy was to restrict the air flow of the pods. I found another site that described a mod that could be made which might compensate for the pods. CV carb mod Namely to drill the hole in the bottom of the slide to allow for more response from the slide/diaphragm given the lower relative vacuum.
Has anybody tried this?
Since the slide needles aren't adjustable on this bike I thought this mod might help some.

It will help somewhat, along with shimming the stock needles 1-2mm. The best way to deal with the lean midrange problem with these carbs running pod filters is to replace the jet needles with ones that have a better taper profile for performance.
The Dyno Jet kit needles have a great profile, and the instructions also call for drilling the holes in the slides.

The current slide needles have no taper at all. If I shim up the needles in the slide will the plastic disc that holds them down in the slide need to be altered?
Can I get just the dyno jet needles alone? I've already got 127.5 mains and #40 pilots.

I'll answer my own question. I called Z1 and Dyno, and you cannot get just the needles
Are there any stock needles that are adjustable and /or have some kind of taper to the tip?

There is an old KZR post with these needles being used. But I have not tried this, as I run an AirBox. Also the stock 81-82 A-1 A-2 shaft drive needle has more Taper, but still only one notch.
www.mikesxs.net/product/48-0663.html

jga2z wrote: I'll answer my own question. I called Z1 and Dyno, and you cannot get just the needles
Are there any stock needles that are adjustable and /or have some kind of taper to the tip?

Here is a thread on the Mikuni needles that are very close to the 5GX29 a 5 clip adjustable needle used in the KZ1100-A non-US models. Sounds like the ticket. Let us know how it werx for you!

Good post Motor Head!!!

kzrider.com/forum/3-carburetor/519737-je...-limited-mods#525572

The link to mod in my first post said to drill out the hole in the slide to 1/8". Does any body say different? The slide needles IIRC do have a taper, but no adjustment for clip. I am going to try the shim method first before getting new needles.
The 83 1100 L1 I'm working on has slide needles with no taper?!?

Without a more aggressive taper to the needle, shimming will help the lower end of the throttle, but I doubt it would be enough for the 1/2 throttle up. I'd get some needles, or just buy the Dyno-Jet kit, if you want the Pod's.

I would go with what Dyno Jet recommends in their kit, a #37. Being how they do Dyno engineer their kits, they have a good data bank of what works and what doesn't.
If you don't have a #37 or can't find one, we use a 7/64 drill bit on our CVK slides. #37 is .104 , and the 7/64 is .109 dia. 1/8 is .125.
I'd rather have it too small than too large. If you go too big, you can close it back up with epoxy then drill it with a smaller bit if you need to.

Motor Head wrote: Without a more aggressive taper to the needle, shimming will help the lower end of the throttle, but I doubt it would be enough for the 1/2 throttle up. I'd get some needles, or just buy the Dyno-Jet kit, if you want the Pod's.

+1 what he said You beat me to it Motor head
I have a set of needles out of an ELR 1000 that look like straight rods with a bevel on the end that goes in the jet :woohoo: Dang those things are L E A N !! :lol: