How To Repair Keihin Carb Slides That Have Been Drilled Larger

Studdard Riefterin · Monday 14 February 2022

Alrighty, I think information technology's fourth dimension to copy some other DIY over

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

I'll also note that you should be

very conscientious when you lot're dealing with the slides as the diaphram volition tear if you're not careful and they are around $100 each!

Alrighty. First (and I'm NOT going to become into it as yous should already know how to practice this if you're going to be drilling your slides) remove the seat and gas tank. While y'all don't have to remove the fairings information technology does brand information technology 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 #ii phillips head.

Pull the cap and...

Remove the leap.

I left the needle in and pulled the slide in a unmarried pace. I prefer to stick a finger IN the slide and gently pulling the slide/diaphram out. Practise this slowly and when at all possible avert contact with the diaphram.

Again when you are dealing with the slide avoid touching the diaphram. Once out yous tin tip the slide upside downward to remove the needle (and any washers that are in at that place).

Hither'due south a picture of a #70 drill fleck. It'south tiiiiiny. Y'all can detect them on eBay SHIPPED For similar $2.l . This would be the 2nd ane. Later I took everything autonomously the original drill bit was no where to be institute. So I literally had to put everything back together and order some other one

... 5 days later:

Here's the bottom of one of the slides. Notice that the hole (not the i in the center) isn't directly between the center hole and the exterior of the tube? When you drill the boosted pigsty (I did information technology opposite the original hole) endeavour to do the same equally the center part of the slide is kind of big and if you lot drill straight between the outside of the slide and the eye you lot'll not arrive through .

Viola! So once again the hole isn't prefectly in between the center of the slide and the exterior. Brand sure to gently blow off whatever plastic cuttings from effectually the slide. Once you're set put everything back together

As has been suggested a picayune vaseline or light grease around the machined groove will help seat the diaphram. You lot tin can see in 2 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 automobile groove for it. It'd be a shame to go through the try 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 kick myself and planning on having to tear the bike Dorsum downwards So I rechecked all the hoses and noticed ane of the vacuum lines pulled out . Upon reconnecting everything was kosher.

After a quick warm-upwardly and jot around the throttle is a bit more responsive below seven,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 departure is when I'd bleep 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 ane of the diaphrams, talk to TheDuck He has a pretty effective manner of patching the diaphram with a prophylactic tire patch that sounds to work.