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I have an 82 KZ 440 that I bought cheap, not running. One carb works, the other does not. The shaft connected to the diaphragm is stuck. Its been sitting outside for months so its stuck pretty good. I'm wondering what the safest way is to get it unstuck without damaging it. I've drenched it in WD 40 and tried prying it with a screwdriver, but that doesn't seem to be helping. All I've taken off the carbs to access these shafts is the bowl covers on the bottom and covers on top. Any suggestions??

Also... Is there anything out there I can use to seal a small crack in the diaphragm??
 

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I'd suggest a good penetrating oil like PB Blaster or liquid wrench to loosen up the stuck shaft.

For a diaphram repair, try this:

I found this the other day concerning carb diaphragm problems.

Carburetor diaphragm repair that works.

Ok so your old bike's carb diaphragm has a little pinhole in it, or you've got a little tear like mine does from being old and maybe a backfire or something. So you go to the dealership or check online and you can't find a replacement anywhere. You may stumble upon services that will re-diaphragm any old carb slide, but the wait time is a month and you can't afford the 170 bucks a piece. Never fear, I have found a solution.

Carb diaphragms are made of nitrile rubber and so are nitrile gloves (big surprise right) so I experimented on several gloves with various adhesives that I thought might work and eventually I found one.

First up was liquid electrical tape. The liquid electrical tape bonded the glove together really quick and held pretty **** strong. Much stronger than needed for a diaphragm. I then tested its resistance to Gum-out (which you should NEVER use on CV diaphragm carbs btw!) and the gumout dissolved it quick. Gumout also slackened and ate through the gloves after several minutes. Well scratch that one, I wanted something that would stand up to gasoline and the occaisional capful of cleaner.

Next up, weather stripping adhesive. This was a good candidate because it seems to hold soft rubber very well for nearly forever. Same problem as the liquid electrical tape. They both smell similar as well which might indicate the solvent being usedm which is easily cut with gumout. I would imagine that xylene and lacquer thinners would have the same effect. I know after painting with nitrile gloves (urethanes, lacquers, clear coats) that the gloves are resistant but will eventually break down anyway. This reinforces the NEVER USE CARB CLEANER SPRAY IN A CV CARB advice.

On the third try, and after reading some industrial adhesives literature, I came across a family of adhesives that include regular super glue, and polyurethane adhesives. You may know the polyurethane adhesives under "Gorilla Glue" or Elmer's "Probond". These guys have di-isocyanates in them and can be particularly nasty, but cyanoacrylates and di-isocyanates are one of the only suitable bonding materials for nitrile rubber, or even hydrogenated n butyl rubbers (the green o rings used in r134 ac systems). And speaking of HNBR (the green rubber), I wish people would push keihn and mikuni and the like to use that stuff in carbs. When you look at what they resist and the temps and pressures they resist, they are CLEARLY the choice for using in a nasty gasoline / solvent environment especially where there is heat involved.... But I digress. So gorilla glue is your best bet. Superglue cures too stiff, and will degrade over time with humidity (crazy huh?). The gorilla glue, being a polyurethane and using the chemicals it does to react with the bonded surfaces, won't let go even when covered with gasoline or carb cleaner. It remains somewhat flexible, but of course is much stiffer than your diaphragm which is just a nitrile rubber coated cloth. You can apply it thinly over tears and cracks and holes and it's not going to let go.

Alternately, some people say that the spray tool dip available from napa auto parts works like a charm. The only problem here is you are increasing the thickness of the diaphragm and that will decrease the response rate of the slide. It's not that big of a deal to get by but still... The main concern is keeping the hole closed #1, and keeping it airtight #2. You could always use a small bead of gorilla glue to hold a tear closed and spray rubber over it for added protection. You could even gorilla glue some nitrile rubber glove over a larger tear. But as I said, response rate will be affected. If you think about it though, there are big springs which hold the slide down, and the suction is really what makes them rise, so as long as they still slide up and down relatively well, and are sealed you should be fine.

The bottom line is, this fix will cost you under 10 bucks and get you going in 24 hours. While you ride on it, look for a new diaphragm, or better yet, save up some money for a set of VMs or something that doesn't use those ?!!&# diaphragms!
 

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WD40 is a very useful spray for a lot of jobs - but it is not really a pentrating / releasing agent !
 
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