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I have a 2007 Kawasaki ZZR 600 that I just recently bought with about 4k miles. It's my first bike and i'm typically always paranoid about something with it. When I bought the bike, the owner said it sat in his shed for about a year so I dumped the old gas out and went to get the carbs cleaned. When I go to warm up the bike ill leave my choke at about half way which throws the idle up to 3k to warm up, and I leave it when im sitting at around 1300 rpm's with the choke off. Today I think I left the choke about 1/5th - 1/4th of the way on accidentally while leaving work. I got to my first stop sign only about a minute after warming up the bike, and randomly it shot up to 6-7k rpms and I thought the thing was going to explode. Quickly I put it in neutral so I could make sure the choke was turned off, and even when it was the rpms wouldn't go down so I eventually had to hit the kill switch. After turning my bike back on I didnt have the issue anymore, but im afraid something similar will happen again. Any ideas on what could cause this, and what I could do to fix it? I feel like I need new spark plugs maybe but thats just a wild guess.
 

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I have a 2007 Kawasaki ZZR 600 ... randomly it shot up to 6-7k rpms and I thought the thing was going to explode.... I eventually had to hit the kill switch.

Any ideas on what could cause this, and what I could do to fix it? .
An ignition (gas) engine throttles the amount of AIR it receives to limit RPMs. Without such throttling, and unloaded (in neutral) it would roar past redline to where it self destructs. (unless it has an electronic rev limiter)

A Diesel engine throttles the amount of FUEL it receives to limit rpms.

If your rpm's shot up, then your THROTTLE PLATES, the butterflies, somehow stuck open, briefly. Probably from goo, old gas, varnish, stuff that makes them stick. Or perhaps a missing return spring.

I don't know THIS particular engine, THIS carburetor setup, it could be it has "slides" rather than butterflies.

You might also have a MASSIVE air leak from a torn boot, whatever, although that lets in air, not fuel/air mix, and tends to stall an engine out rather than zoom it, UNLESS the choke were on, etc.

I'm going to suggest it is NOT a problem with your spark plugs (which only IGNITE the fuel/air mix), nor your choke (which ENRICHES the mixture) but doesn't control HOW MUCH air/fuel "charge" your motor is receiving. (although the choke TENDS to limit the total amount of charge available, since it too 'acts" like a throttle plate.

I'd suggest you either pull your carbs, order rebuild kits, and take them to an "expert" for rebuilding or have a qualified motorcycle tech "look at" your throttle control cables, butterflies, slides, return springs, or whatever and figure out what stuck on you.

IMHO You need help from an expert, unless you are willing to risk redlining and cratering your motor if you don't get it repaired right. I don't mean to be negative but learning MC repair "the hard way" is hard on the wallet AND ego.
 
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