What effect does drilling the slide have on a CV carb

[JTGS850GL]

Just curious as to what is actually being achieved on a Dyno Jet stage 3 modification by drilling the slide hole larger? The reason I'm asking is because I recently acquired another set of BS34SS carbs that, at some time, had a DJ kit installed. Since then all the obvious jets (Pilot Air, Main, Pilot) had been return to normal, but the main air jet insert was still installed and the slides were drilled. I've since removed the main air jet inserts. So now the only thing I can't return to stock are the drilled slides.

So what effect would running a stock configuration with drilled slides produce?

 

[dorkburger]

Not exactly sure, and ive always wondered that too. My old 83 1100e came with a jet kit installed by my brother, and he did not drill the slides ( he said the kit made no mention of it, nor did it have a drill for them) my 1150 slides were drilled ( 2 different carbs, I know)
The 1100 seemed to take a tiny bit longer to return to ible after after revvivg it. Im guessing that the larger hole lets more air pass thru the slide hole and drop the slide quicker.

 

[Steve]

I think dorkburger has the idea "lets the slide drop quicker". It might actually enhance movement inboth directions.

However, it is not the slide that determines the idle speed or the quickness of return to it. The butterflies do that job.

It it my impression (and I could be very wrong) that drilling the slides allows the slides to lift quicker (not necessarily sooner, though) for enhanced throttle response. Since the main purpose of the CV-type carbs is to keep air moving over the jets, I am not sure how much of an advantage that is on a street-ridden motorcycle. In racing situations, sure. Maybe even when "racing" through the twisties, but for most of us, the standard hole in the slide will do just fine.

Will the larger hole affect your daily riding? Not sure, but if you want, you can put some JB Weld in the holes and re-drill them to the stock size. Be careful, though, those holes are NOT drilled straight, they are at an angle.

.

 

[salty_monk]

I went back to stock on a set of CV34's. Left the slide holes & didn't notice anything bad.... (I'd ridden with them both unmodified & then modified prior to that so plenty of experience with that bike setup. Was on my 1000G).

I've also JB welded a set & re-drilled the holes - also seemed to work fine.

 

[JTGS850GL]

Thanks for the feedback. I'll just leave them drilled as is and see how it goes.

 

[jstewart]

according to the dynojet rep at the dealers show 35 year ago it is done to allow the slides to open faster. This was back when all they made was jet kits.

 

[JamesWhut?]

And close faster too in order to make CVs behave more like round/flat slides. Back then, all there were were jet kits...