CV slide drilling

Out of curiosity if you replace your stock airbox would that decrease vacuum to the slide due to more airflow? Could this be remedied by drilling that little vacuum hole to make the slide lift completely up?

Or on the other hand would it just be better to use one of my spare mikuni round slide carbs on this 250

gonna go pod, huh?

I just went through this. You are talking about an rk29, right?

I didn't end up drilling the slide, but the klr guys seem to... something about needing the quicker throttle respose in the woods.

Here's what I ended up with:

.040 worth of washers under the needle to shim it, you can still get the c-clip back in the grove inside the slide.

105 main (98 is stock) keihin, not dynojet.

the stock pilot is good, just as long as the rubber plug stays in place.

BTW, I'm using an emgo pod filter... no oil.

good luck,

Matt.

Yes, removing the airbox does reduce the amount of vacuum available to move the slide. Drilling the hole larger will not remedy this.

Drilling the hole larger doesn't change the average level the slide rises to, but it does make the slide react faster. However the side effect is that it also makes the slide far less stable. It will move up and down more with each intake cycle whenever the slide is at an intermediate position.

I would make drilling the slide the last option, since it's a very difficult thing to change back.

both awesome replies! have 105 jet and is perfect with my UNI pod and matt awesome bike! that circlip in there what did you use to pull that out my circlip pliers dont wanna cooperate to get it out

Why drill the slides I dont understand???? :dry:

I would love to see a link to info on this.

man, that snap ring is a fight! I ended up taking my little craftsman needle nose pliers kit and modifying the long ones by grinding the ends to fit in the holes to get it out... my smallest snap ring pliers wouldn't fit either.i squeezed it, and very carefully used a flat head glasses screwdriver to massage it out f the groove. it won't fly out, but it will damage fairly easily, so take special care.

@ready2ryde1985:

google klr .22 mod, or 22 cent mod, and you will get several forum articals to sift through. It basically means that you buy a couple small washers to shim up the slide needle, and drill out the vacuum hole in the slide to 7/64"(don't quote me on the size)... more pick up is what they say, from the needle raising quicker. this is a common mod for dirtbikes with a single cv carb.

Matt.

Thanks for the tips ill attempt that tonight, gotta love these old small bikes :woohoo:
wish I coulda seen a build on your white bike matt.
And since you gotta 250 around what is the top speeds of these bikes ive been trying to figure that out for a small trip on this bike

Dyna Jet Kits come with a drill bit specifically for drilling the slides so they respond correctly to the difference in vacuum. Its only very slight increase in diameter! They work very well and deffinately make a big difference in the performance of a vacuum slide carb. I've tried with/without, would never go back.

You can fill the slide hole with solder and re-drill smaller if necessary, its not that hard, just time consuming!

I would think it safe bet to be able to ride about 70 - 75mph for extended periods of time, but when i first got this bike it was way lean because it didn't have an air filter, so i was only able to do about 53 or 54mph. The 75mph is the '86 klr250 that i used to ride on the highway...

Also, i've stripped most of the factory parts off of the little guy, so of you are going back stock, let me know in a PM if you need something.

Matt.

hey matt last ? before a follow up on how it runs
did you use a #4 washer and if so how many?

i went to an rc plane shop with my slide needle and got some washers that fit on. they were .020(20 thousandths of an inch on a mic) each in thickness, so i ended up stacking 2. i will go out to the garage and see if i still have the package... i think that a 6 pack of them was like $1.25 or something...

Matt.

they are 1/4" o.d. 1/8" i.d. give or take a couple thousandths... I think that they are #4, but the bag is blank.

Matt.