Help: Carb kz650

[xbmxxx]

I am working on getting a kz650-4 running for a friend of mine. It was not running when I got it. I completely disassembled the carbs, soaked in carb dip, blew out passages with carb clean then compressed air. Reassembled them, set the needles as per the manual, and now it starts right up with a bump of the key and runs fine, with the choke on. With the choke off it stutters, flat spots, and won't idle at all.

Any suggestions on what to do next?

[JustinP]

Does that have the CV carbs?

If so check the diaphragms for pin holes or rips or replace them if they are baggy and wrinkled looking.

Clean the carbs again, clean the tank, put an inline fuel filter in.

But my number one guess is the rubber manifold between the carb and the jugs are leaking.

With the engine running hold an unlit propane torch around each rubber boot. If you hear a change in the way the engine is running you have a manifold leak.

[xbmxxx]

Does that have the CV carbs?

If so check the diaphragms for pin holes or rips or replace them if they are baggy and wrinkled looking.

Clean the carbs again, clean the tank, put an inline fuel filter in.

But my number one guess is the rubber manifold between the carb and the jugs are leaking.

With the engine running hold an unlit propane torch around each rubber boot. If you hear a change in the way the engine is running you have a manifold leak.

No, they aren't the CVs. There is an inline filter in the line, but I have not looked inside the tank. I did the carb boot leak test (but with carb clean) and it did make the engine rev. however, I tested it on my bike and it did the exact same thing, and mine has no idle issues. Is there a difference between the propane method and the carb clean method?

thanks for the suggestions.

[JustinP]

Propane, carb cleaner, WD40 all functions the same, propane is just not messy.

If the rpm's go up when you spray the boots they are sucking air. Yours may not be as bad as your friends, but they are leaking.

I think the carb boots are the problem or at least part of it.

If you need to choke it to keep it running when it's warmed up, it's running lean. Sucking in air through a leak will cause that.

Also is the exaust and air filter stock? If those have been changed and the carbs were not re-jetted that could be adding to your trouble too.

[johnnybarndrunks]

What JustinP wrote + I know that some carbs have lean setups described in their shop manuals due to emissions restrictions. For example, on my wifes scoot (XS400) the manual states 1,5 turns out (probably to meet emissions restrictions) but that's way to lean when I do a plug chop. It runs perfect at 3 turns out.

But start with a possible air leak, if your 100% sure that your carbs really clean. Last op would be the mixture screw.

[Bear]

My 2 cents sounds like Carb boots. -Bear