Carburetor Diaphragm Repair

bountyhunter wrote:

otakar wrote:

bountyhunter wrote:

mkeating wrote:

How much would a couple of tiny holes affect the performance.

More than you would believe. It keeps the slides from rising at small throttle openings giving poor throttle response.

Actually the slides do not start opening until the throttle is about a quarter open so a tiny pinhole will not do much damage.

I guess it depends on what we call a small hole. Mine each had a couple of tiny slits maybe 1/4" long and were giving really bad throttle response. I had to compensate with larger pilot jets and moving the needle to get it rideable. Once I plugged the slits, it ran normal again. Amazing how long I screwed with the carbs before I found those little slits in the "lace curtains" near the rim of the rubbers.

I am talking about a "pinhole" or two. A slit or a tear is a different matter altogether.

Just to clarify, I have three small holes, roughly about 2mm wide on each of the diaphragms.

mkeating wrote:

Just to clarify, I have three small holes, roughly about 2mm wide on each of the diaphragms.

IMHO, that will screw up performance.

I also have 1981 kz 440

I used Gorilla Glue on my carb diaphrams.
Use a cotton swab (Q tip) to apply on both sides of hole.
Gorilla glue tends to puff up in about 5 min or so, if this happens just push the puff down with your finger. Do not get any water or liquid on the glue until it is dry, this make the puffing worse. Also use as little glue as possible.
Any way this is working for me.
Good luck

mkeating wrote:

Does anyone know where you can buy the grease paper that the adhesive will not stick so that you can plug the hole while you spray it??

Greaseproof paper
Look in your local supermarket in the baking supplies aisle.
It may also be called baking sheet. Comes in a roll in a cardboard box. Made by Glad

mkeating and the rest of you, thanks a bunch for getting this conversation going! At what point should you just replace your diaphragm skirt? After 3 holes? If they are more than 2mm in dia? I wish o knew why my right side was in such bad shape with the left just perfect. I'm off for some gorilla glue and PD in the meantime. Thanks a ton!

Jbosh wrote: mkeating and the rest of you, thanks a bunch for getting this conversation going! At what point should you just replace your diaphragm skirt? After 3 holes? If they are more than 2mm in dia? I wish o knew why my right side was in such bad shape with the left just perfect. I'm off for some gorilla glue and PD in the meantime. Thanks a ton!

I'd get a new slide or replace the diaphragm. There are aftermarket diaphragms available. Search out the source with google.

There is a seller on eebbaayy who sells the diaphragms & has a good how-to w pics. I've seen them for the 440.
JBM Industries is another place.

eebbaayy search = kz440 diaphragm rubber

jbmindustries.com/Keihin_diaphragm.html