ok, so after reading some write-ups here about shimming needles, jetting, etc....etc.... and having seen various pics of peoples carbs apart and reading both opinions on whether to drill the slide like dynojet says, i decided to investigate.

my reasoning is, if it would benefit the ninja, then WHAT is the benefit, and would it also benefit my cruiser??? and if it would, then why does dynojet NOT mention anything about drilling on my bike.

so i e-mailed them.


ME WRITING TO DYNOJET:

Make: Suzuki and Kawasaki
Model: VL800 and EX250
Year: 2004 and 2007
Jet Kit P/N: 3195 and 2138
Exhaust: debaffled and stock
Air Filter: uni and stock
Airbox: removed and stock
Other Modification:
Main Question/Comments:

I was looking at a jet kit for my wifes EX250 just to do some fine tuning, and noticed that you guys include a drill bit and your instructions say to open the vacuum hole at the bottom of the slide. from what i can tell that would improve responce time by increasing vacuum (i believe). so it got me thinking about my VL800, and i looked at your jet kit for it and noticed that you don't have anything in there about drilling the slide. I was just wondering why that is, and if there is any reason that i shouldn't do the same thing to my carb for some slight improvement. currently my bike is running fine and very strong with the tweaking i've done so far and i'm overall happy, but i love to thinker, and this just seems like something worth looking into. thanks.


REPLY FROM DYNOJET

Enlarging the slide lift hole allows the slide to lift faster for improved throttle response. The EX250 has a very heavy aluminum slide and need the larger hole to help it lift. The VL800 has a plastic slide that is fairly light and the stock slide lift holes are sufficient for good response.



Michael Cory
Research & Development


MY REPLY TO DYNOJET

That explanation actually makes perfect sense, except for one little detail. the slides are plastic. I just had the carbs apart a couple days ago trying to diagnose a running issue that I have, and they are very light black plastic.

Also on various ninja 250 forums that I've been on lately trying to get help with this problem I'm having, I have seen pictures of various people with their carbs apart and they also seemed to be black plastic.
Just incase, the carbs I pulled out of my 250 show up as the kei-hin CVK40.

Thanks.

i just realized that i mistyped the carb model. it should be cvk30. but that little error aside, i wonder what they are going to reply about the fact that the slides are NOT aluminum, and therefore they have been incorrectly telling people to drill their slides.



or do any of you guys have aluminum slides and perhaps there was a year brake somewhere at which point they used either or???

Mine are plastic and I rejetted my carburetors manually w/o a jet kit. I did not drill my slides.

Just save your money and buy some washers from the local hardware store and stop by the MC parts shop to buy some Keihin round screw main jets. I spent less than $20 for everything.

Mine are plastic and I rejetted my carburetors manually w/o a jet kit. I did not drill my slides.

Just save your money and buy some washers from the local hardware store and stop by the MC parts shop to buy some Keihin round screw main jets. I spent less than $20 for everything.

i'm fully aware of that. the point i'm getting at is the point with the drilling. obviously we can also get our own bits if we don't already have them. but i like to research new stuff first before just jumping in after the first person. LOL





anyways i got another reply from dynojet

REPLY FROM DYNOJET
Ya that right they did change to a plastic slide a few years back. When we do the testing for the jet kit we check to see if there are any gains available from drilling the slide with out causing driveability issues. There was not any benefit or even a loss of drivability with the slides drilled on the VL800, so we do not recommend do it.



Michael Cory
Research & Development

MY REPLY TO DYNOJET
so am I to assume based on your first explanation that since they changed the ex250 to plastic slides, that they should NOT be drilled now???

REPLY FROM DYNOJET
The slides still need to be drilled on the Ninja 250, they restricted the plastic slide to move the same as the aluminum slide.

Scorpio, with their latest response to drill the slides on the 250 even though they are plastic. Do you reccomend drilling the slides? and if so what size is the drill bit?

Scorpio, with their latest response to drill the slides on the 250 even though they are plastic. Do you reccomend drilling the slides? and if so what size is the drill bit?

i haven't personally done it myself, but was researching it a bit. the theory behind it makes sense and should speed the response time by creating more vacuum. i'll try it down the road after i get these problems that i've been chasing the last week figured out.

once i get the bike working properly again, then i might give it a try. worst case scenario, you can always reseal the hole you drill with some good quality plastic epoxy.


i also don't remember what drill bit size. you might want to check on the dynojet website and see what size came with the kit and read the pdf instructions they have there, or do some google searching. if i remember it, i'll post it back up.

http://www.ninjette.org/forums/showthread.php?t=10736

hmm why dont you take years of experience and not drill the holes? have you never read anything on 250.org. oh yeah ask a company anything , you think you matter to them. serious wow. hey i got some harley carbs ill sell ya they will bolt right on and give you mad horse power

hmm why dont you take years of experience and not drill the holes? have you never read anything on 250.org. oh yeah ask a company anything , you think you matter to them. serious wow. hey i got some harley carbs ill sell ya they will bolt right on and give you mad horse power


why don't you tell us how you really feel???:D:D:D

http://www.ninjette.org/forums/showthread.php?t=10736

interesting idea to drill a secondary hole. i looked up the info on the dynojet site, and it looks like they are using a 7/64 bit to enlarge the existing vacuum hole.

be careful of making that hole too big. the carb will not work properly. that's why we ended up using the size drill bit we did.

good thing is, if you don't like the change, just epoxy the hole back up and you're back where you started. just be careful playing with the slides and the vacuum diaphragms very easy to damage them and a new slide is something like $100.

aahh........didn't know you guys had already tried enlargening the hole. i had seen the writeup with the new #70 drill bit, but don't remember if i saw anything about you guys having tried to just enlargen the hole .

you are correct... we didn't enlarge the hole, just added another to supplement what's there.