DIY - Drilling your carburetor slides

[VeX]

Alrighty, I think it's time to copy another DIY over

Drilling the bottom of the slides on these carburetors makes the needles respond faster. In the low to mid range of the RPM band it'll make the carburetors a little more responsive. This in no way is a way of 'gaining horsepower', but is more 'fine tuning'. I therefore don't recommend doing this unless you've already torn into the carb's a couple of times and are looking to get your carburetors tuned to their maximum ability.

I'll also note that you should be very careful when you're dealing with the slides as the diaphram will tear if you're not careful and they are around $100 each!

Alrighty. First (and I'm NOT going to get into it as you should already know how to do this if you're going to be drilling your slides) remove the seat and gas tank. While you don't have to remove the fairings it does make it a little easier to get the tank off.

Remove the gas tank and tackle the carburetors one at a time:

To avoid stripping the screw heads, I recommend an angle screwdriver head with a #2 phillips head.


Pull the cap and...


Remove the spring.


I left the needle in and pulled the slide in a single step. I prefer to stick a finger IN the slide and gently pulling the slide/diaphram out. Do this slowly and when at all possible avoid contact with the diaphram.


Again when you are dealing with the slide avoid touching the diaphram. Once out you can tip the slide upside down to remove the needle (and any washers that are in there).


Here's a picture of a #70 drill bit. It's tiiiiiny. You can find them on eBay SHIPPED For like $2.50 . This would be the second one. After I took everything apart the original drill bit was no where to be found. So I literally had to put everything back together and order another one

... 5 days later:


Here's the bottom of one of the slides. Notice that the hole (not the one in the middle) isn't directly between the center hole and the outside of the tube? When you drill the additional hole (I did it opposite the original hole) try to do the same as the center part of the slide is kind of large and if you drill directly between the outside of the slide and the center you'll not make it through .


Viola! So again the hole isn't prefectly in between the center of the slide and the outside. Make sure to gently blow off any plastic cuttings from around the slide. Once you're set put everything back together


As has been suggested a little vaseline or light grease around the machined groove will help seat the diaphram. You can see in two pictures up a bit of grease on my diaphram from this . Pay special attention upon reassembly to make sure the diaphram is fully seated in the machine groove for it. It'd be a shame to go through the effort only to tear the diaphram when you put the cap back on

The idle was crappy after I got the bike back together and started it. I was kicking myself and planning on having to tear the bike BACK down Then I rechecked all the hoses and noticed one of the vacuum lines pulled out . Upon reconnecting everything was kosher.

After a quick warm-up and jot around the throttle is a bit more responsive below 7,000 RPM or so. I'd say it was worth it (probably worth doing if you're already there fine tuning needle height). The biggest noticable difference is when I'd blip the throttle on downshifting. Sometimes the throttle was sloppy when I blipped it, but now it seems more instantaneous. Me likeys!

BTW: If you do tear one of the diaphrams, talk to TheDuck He has a pretty effective way of patching the diaphram with a rubber tire patch that sounds to work.

[kkim]

lol... I was wondering when this one would show up. That drill bit looks awfully familiar.

Whatever you do, don't post up a cush drive DIY or Richard will go bonkers.

[Syphen]

I shimmed the needles with 2 #4 washers per needle and tore the snorkel out of the bike. It made a huge difference to the responsiveness. Have you done this as well as drill the slides out?

[VeX]

I'm surprised he got steamed on that one. I think perhaps he was more leaning towards the people going a bit over the top on such things. ie. putting a solid cush drive in. Now THAT is foolish to me.

[VeX]

Originally Posted by Syphen

I shimmed the needles with 2 #4 washers per needle and tore the snorkel out of the bike. It made a huge difference to the responsiveness. Have you done this as well as drill the slides out?

Yes. Well yes and no . Drilling your slides and shimming your needles does two different things. Shimming the needles affects the amount of fuel that enriches the mid-RPM power band. drilling the slides affects how quickly they move. So I have Factory Pro needles that are adjusted (same thing as shimming needles) and the slides drilled.

Kawasaki was pretty close when designing the total size of the opening to the slides so it's a very small hole I drilled. TheDuck tried a larger bit (I believe it was a #50) and the engine bogged as the needles moved TOO quickly and suddenly the bike was too rich. He then epoxied the holes and stepped down to a #70 and the result was spot on. I've tried the #70 and got the 'desired result' and am content as well

[Syphen]

Well, maybe I'll try it out on the 250r with washer shimmed needles. Let people know how it goes.

That is if I can convince my fiance to let me take it all apart again. she was really apprehensive about letting me rip into it the first time.

[kkim]

Greg- if you're going to tear into the 250 "one last time", consider taking the mixture screw plugs out so you can tune the idle circuit as well.

[kkim]

Drilled my slides tonight. Not much to add to Vex's DIY except I used a pin vise with the #70 drill bit. To give you an idea of exactly how small a hole we are drilling, here's a picture of the bit in comparison to the Ninja key.

Thanks, TJ. Can't wait to try it out. Hope it runs.

[Tigerpaw]

Got my #70 (.028) bit from local Grainger($1.60). Home depot&lowes wasted my time. I lost it in the packaging for a second Somehow it fit in my B&D drill chuck. Still working other stuff...so I haven't tested it yet.

Awesome write-up

[kkim]

if anyone is interested in doing this mod and is having a hard time getting a #70 bit, PM me and I'll be happy to send you the one I used for free. I got the one I used from Vex as I could not find any on island and shipping to Hawaii was more than the bit was worth through a vendor. Throwing it in an envelope and mailing it somewhere costs the price of a stamp.

[randomwalk101]

kkim, notice any difference with this mod?

[kkim]

I'm ashamed to say I've not ridden the bike yet since doing this.

[voodoomaster]

Originally Posted by Syphen

I shimmed the needles with 2 #4 washers per needle and tore the snorkel out of the bike. It made a huge difference to the responsiveness. Have you done this as well as drill the slides out?

What's a snorkel????

[kkim]

http://www.ninjette.org/forums/showthread.php?t=10090

http://www.ninjette.org/forums/showthread.php?t=5586

[rallyegolf]

just curious how deep do you drill the hole? The slide looks like a solid piece to me, but maybe I am mistaken. Do you just drill until it goes through the other side? I have never pulled the slide out.

thanks

[kkim]

yes, all the way through like the hole that's already in there, only on the opposite side of the slide.



the larger, towards the bottom, is the present hole, the smaller, at the top, is the one you drill. the largest one, in the middle, is the hole that the needle slides through.

As Vex said, be very careful of the hole placement. Look from the inside of the slide to clear the slide "wall". basically, put the center of the new hole the same distance from the side of the slide that the center of the present hole is.

If you've never done any jetting to your bike, I don't know if this is such a good first jetting mod. This is like a fine tuning after all the major jetting stuff has been done.

[rallyegolf]

I jetted my bike, but never pulled out the slide so I didnt know if you drill "through" the slide , or just "into" the slide. If that makes sense.

Thanks for the info. Im jetted and have the area p, so im sure drilling the slide will also help the motor run smoother.

[kkim]

cool... I'm sure it will help. I've not ridden mine yet since drilling the slides, but plan to later this morning.

[kkim]

Got to ride the bike on the street today. It does seem a lot smoother when downshifting and blipping the throttle. The response is improved and very "instantaneous" feeling.

Haven't ripped through the gears in the mountains yet, but I'm sure the throttle response will be great for entering corners and blipping the throttle when downshifting.

I didn't know what to expect and how this mod would really affect the bike, but I've got to say... I like it!

Thanks for the bit, TJ!

[randomwalk101]

nice...i've bought an extra 08 carb and it's been sitting there for the last 4 months or so..bought it to do this mod just in case I mess up i'll find the time to do this sometimes...the women has been keeping me busy

[voodoomaster]

Originally Posted by randomwalk101

nice...i've bought an extra 08 carb and it's been sitting there for the last 4 months or so..bought it to do this mod just in case I mess up i'll find the time to do this sometimes...the women has been keeping me busy

The a set out on EBAY...I was thinking the same thing. Buy them to make the mod on and have a spare set just in came things get FUBAR.

[Sound Wave]

bumping this one back up for info.

so just verifying... if all i have done is the shimming, removing my snorkel, and switching to a drop-in k&n filter, i should NOT do this mod yet?

only if i have changed the jets? what would happen if i did this mod without jetting? thanks.

[kkim]

you could actually do this mod at anytime, as it is really to fine tune the the throttle response/revability of the bike. It is letting more air pass quickly so the slides can move up and down with less restriction from the diaphragm.

Do you find the throttle too slow for you as far as coming back down after you close it?

[Sound Wave]

no i don't notice the throttle being too slow. then again, i have no other bike to compare it to.

i am just a sucker for cheap, effective mods.

[kkim]

while it does make a slight difference in throttle response, the risks far outweigh the benefits if you are just doing it for the sake of doing it. remember, you'll be playing with those $100 slides and the chances of tearing them is much greater as you'll have to remove them from the bike to work on them.

my main interest in this was due to the fact that I "blip" the throttle on all of my downshifts and most of my upshifts, too, so timing the shift has become easier with the quicker response of the carbs.

[Sound Wave]

hmm... one of those "if it ain't broke..." things, eh?

i guess i can pass on this one then. i don't know if my throttle is slow or not. seems fine to me. i don't even know how to blip the throttle when downshifting. tried with both my cars and this bike. can't get the hang of it.

anyways, thanks.

[voodoomaster]

Originally Posted by kkim

if anyone is interested in doing this mod and is having a hard time getting a #70 bit, PM me and I'll be happy to send you the one I used for free. I got the one I used from Vex as I could not find any on island and shipping to Hawaii was more than the bit was worth through a vendor. Throwing it in an envelope and mailing it somewhere costs the price of a stamp.

Still have that drill bit K?

[kkim]

sure do. you braving opening up the carbs now?

[voodoomaster]

Originally Posted by kkim

sure do. you braving opening up the carbs now?

hummm....After adding the white stripes to VoodooMaster I have decided that I like her and might keep her on hand. I think it is time to dig into the fuel line. I can't stand the on-again, off-again start problems that I have experiences, so I am going to add the washers, and then tweek the idle mixture screws. I bought a set of carbs from EBAY and dismantled them last week. They cane apart easily enough. The slides and the jets are straight forward and the lead plug came out from the mixture screws without toooo much effort. I finally got in one of those offset screw drivers from Milwaukee, so I think I have almost everything I need. If you happen to have 4 of the CORRECT size washers for the jets in your pocket, I would be happy to let you give them to me!! The washers I have might be the right ones, but my mechaical skills are weak when it comes to telling a number 4 washer from a number 6 lug ().

The low end operation from idle seems to be crappy. When I twist the throttle a bit too fast she seems to bog a bit. Could be just me. Mid range seems fine for a 250. Operation past 7K is outstanding for a 250CC machine. It's the start-ability and low end operation that I just hate. I don't plan on adding a noisy exhaust, or bigger jets any time soon. Actually, never will mod the exhaust unless I can put an under-tail unit on her like the 600 has. Anyway, time to fix what I can on those two fuel mixing units..... fuel injection would have been the way to design this one.

Dave

[kkim]

lol... I recommend shimming as a cheap, easy, non invasive way to fix the lean condition of these bikes. You are about as invasive as you can get working on an entirely different set of carbs. I assume you're going to work on the purchased set and swap them in after you're done tinkering?

If so, get a jet kit at this point. I hesitate from recommending a jet kit due to the hassle of pulling the carbs. Since you have them out, it makes more sense for you to install a jet kit now and reap the maximum benefits of jetting. I have a Factory Pro kit, but Dyno Jet makes one, too. Either will do.

Even with the stock exhaust, you'll notice a big difference with a properly jetted bike.

[almost40]

Originally Posted by kkim

while it does make a slight difference in throttle response, the risks far outweigh the benefits if you are just doing it for the sake of doing it. remember, you'll be playing with those $100 slides and the chances of tearing them is much greater as you'll have to remove them from the bike to work on them.

My 2 cents worth on this issue is I DO NOT think this mod is worth it for the above reason and there is nearly nothing to gain here. Yes there may be a SLIGHT advantage in response but in my opinion is not worth it.

[voodoomaster]

Originally Posted by kkim

lol... I recommend shimming as a cheap, easy, non invasive way to fix the lean condition of these bikes. You are about as invasive as you can get working on an entirely different set of carbs. I assume you're going to work on the purchased set and swap them in after you're done tinkering?

If so, get a jet kit at this point. I hesitate from recommending a jet kit due to the hassle of pulling the carbs. Since you have them out, it makes more sense for you to install a jet kit now and reap the maximum benefits of jetting. I have a Factory Pro kit, but Dyno Jet makes one, too. Either will do.

Even with the stock exhaust, you'll notice a big difference with a properly jetted bike.

HA! Sorry, my bad. No, those cheap carbs were from a 2005 model, and were only for me to fart around with...to figure out the degree of difficulty of disassembly. I won't be swapping those into my 2008 machine.

[voodoomaster]

Originally Posted by almost40

My 2 cents worth on this issue is I DO NOT think this mod is worth it for the above reason and there is nearly nothing to gain here. Yes there may be a SLIGHT advantage in response but in my opinion is not worth it.

Good input. What's your take on the needle shimming and idle screw adjustment process?

[kkim]

if you are thinking of going as far as drilling out the mixture screw caps, I think a jet kit is the way to go, other than the price of the jet kit.

[almost40]

once again Kkim is correct. If your pulling the carbs might as well put in the jet kit. If you have a full exhaust or are planning on getting one. Its a no brainer. You will feel a MAJOR horsepower improvement over just shimming the needles, at the cost of a few mpgs. In my opinion All these bikes need is a full exhaust (of your choice) and a jet kit. Just follow the jet kit instructions and you'll be rewarded.(Gearing is a option, and a cheap one at that.)

[VeX]

that little drill bit is really going to make its rounds I'm feeling

[kazam58]

Did this mod today, along with switching out the stock needles for Dynojet ones. I figured why not, since I was already inside the carbs. It's a super easy mod, I must say, it only added like 5 minutes to the overall time and it seems to be pretty effective. Though most of what I'm feeling on the bike probably has to do with switching the needles and yanking the snorkel. This is still the best $1.77 I ever spent on a drill bit.
If an 18 year old with no previous motorcycle experience can do this right, anyone can

[rockNroll]

Just a little tidbit, I found the bit at harbor freight in this mini set for $4.

http://www.harborfreight.com/cpi/cta...emnumber=91682

[shadow]

ok question on the slides - when i did my needles i didn't tear, or pull or stretch the slides (or the diaphragm part) but I used my fingers to work the edges of the diaphragm up and off the edges of the carb, and when i put them back, they just seemed to sit there. didn't give any sort of tug or resistance (like glued in) when i tried to pick them back up and out (from pinky in the center "needle" hole) but didn't seem to be out of alignment on the edges, just right back to where they were. Also when handling the diaphragm i definately was putting my fingers all over the "mushroom top" or thin diaphragm part...will this inhibit or damage those parts? I'm a new bike and VERY new carb person...
also, the bike now doesnt have the same engine rhythm than before i did my needles (#3 notch, DynoJet kit with 2 washers, no snorkel, plugged kleen-air and two-bro slip on)...but i know that a needle mod also usually requires re-syncing the idle circuit and doing jets as well (#100 Keishin is my guess, wednesday maybe)

[kkim]

As long as you didn't rip or tear the diaphragms, you're fine.

You should sync the carbs if you're getting a rhythmic pulse.

also, I'd stay with the stock 98 mains for now until you determine you need to go richer.