Does this sound like a vacuum leak problem?

What are the normal symptoms of the leaks? I have an 81 kz440 that idles rough and very differently when it's cold than warmed up (like from 500cold-4000 when warm) also the rpm varies on constant throttle. When I carb clean tested the boots one of them reacted consistently when sprayed. Could these symptoms possibly be alleviated by new boots, and if so where could I find them?

Yes; those are classic carb holder leak symptoms. If you had any reaction at all (which you did) to the carb spray test you need to replace the carb holders. The good news is that according to Kawasaki.com yours are still available (Active) from Kawasaki (see image). Partzilla (see first link) lists them at $23.70 each; replace both. You should soak the carb holder screws with Kroil for a few days before trying to remove them because they will be stubborn to remove, and be SURE to use JIS screwdriver bits, the stock crosshead screws are NOT Phillips (see info under "TOOLS" in second link). Ed

find.partzilla.com/?r=t&q=16065-1027&x=10&y=9
kzrider.com/forum/10-new-members/589649-...r-savannah-ga#594587

I'm not too fluent with carburetors but I know that trying to diagnose further without leak free boots is a pain in the A. I was trying to adjust my carbs with leaking boots and I never got them right because of it.

This website is on carb theory on mikuni carbs. Its well written and very easy to understand.

What ed said, plus, once get the screws out, go to Ace (or your favorite big-screw selling hardware store) and replace those screws with Allen Head screws. It will make your life easier in the long run.

peavylotus wrote: I'm not too fluent with carburetors but I know that trying to diagnose further without leak free boots is a pain in the A. I was trying to adjust my carbs with leaking boots and I never got them right because of it.

This website is on carb theory on mikuni carbs. Its well written and very easy to understand.

Thanks for the link!

Good Fortune!

I took off the boots, put some gasket sealant around the lip and put them back on. After it all settled it ran much better. Hopefully this is permanent. Also I finished my top box project

delta 224 wrote: I took off the boots, put some gasket sealant around the lip and put them back on. After it all settled it ran much better. Hopefully this is permanent. Also I finished my top box project

Likely not very permanent.

Let us know what sealant and how it works, as most reports show only temporary success, with sealant not being both heat-proof and fuel-proof for the long term.

Am recalling that Yama-Bond is superior to silicone based sealers in this particular application.

www.z1enterprises.com/ItemDetails.aspx?i...+1194&item=TU53-0395

The product is promoted as follows:

ThreeBond 1194 is a semidrying liquid gasket whose major component is special synthetic rubber. After it is applied and dried, it will form a rubber-like elastic body. Since it excels in padding property, it shows a high sealing effect on bonded surfaces that have poor flatness and large clearance. In addition, it has excellent resistance to water, oil and gasoline.

High padding property.

It shows an excellent sealing effect not only on normal bonded surfaces, but also on bonded surfaces with large clearance.

Excellent resistance to vibration and impact.

After applied and dried, it will form a rubber-like elastic body and exhibit excellent resistance to vibration and impact.

Excellent resistance to high and low temperatures.

It keeps stable rubber elasticity in a wide temperature range from -40°C to 150°C.

Excellent resistance to water and oil.

Effective in preventing leak from threaded portions.

Sealing of flange surfaces and threaded portions.

Applicable to sealing of flange surfaces having large clearance.

For sealing other coolants.


Good Fortune!