Fast Idle After Top End Rebuild 04 636 - ZX6R Forum
 
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post #1 of 5 Old 12-01-2010, 04:15 PM Thread Starter
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I Ride: 2004 Kawasaki ZX636B2
Fast Idle After Top End Rebuild 04 636

After high siding my bike and not riding it forever i decided to do a top end rebuild on it for some entertainment. i reground the valves for a better seal, put all new seals in, did a valve adjustment. I took the throttle bodies apart to clean them and put them back together pretty easily. I made sure the throttle plates were set just to the point that they were closed.

put the motor back together which was alot easier than i thought and got it back in the bike. a very small bit of very old gas was in the bottom of the tank but it was diluted with two gallons of fresh 93 octane the other day.

i started the bike up. it cranked, turned over easily, but sputtered out very quickly about three times. the fourth time it fired right up and ran smoothly.

now the concerning parts... it idles around 1800rpm when hot (~200 degF) and the exhaust coming out of the muffler feels a little puttery and not very smooth. i have the idle adjuster backed all the way off and again made sure the throttle plates were closing all the way. in the first 7 minutes of running it got close to 2500rpm but has since backed down to around 1800rpm and remained steady there. with respect to the exhaust feeling funny when i put my hand over it, the motor sounds like its running very smooth and maybe smoother than it ran before.

perhaps if i run the motor a little longer and let it run for a bit maybe take it out on the street for a few it will slow back down to its low 400rpm ish that it would run at before rebuild (with the idler backed off all the way of course). it has also been at least two years since i remember feeling the exhaust with my hand so maybe i just worry too much. i triple checked everything during reassembly but there is always that chance i missed something.

if anyone happens to have input please spit it to me. the engineer inside me could be worrying just a little too much but i always like to make sure. thanks for reading. take care everyone.
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post #2 of 5 Old 12-01-2010, 11:03 PM
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I did the same thing this past weekend and found the EXACT same results. I started with a vacuum leak and the bike wouldn't run under 3k. Located and fixed the leak, and now it won't run below about 2200 rpms. Anything lower than that and it just falls flat on its face and sputters out. I deglazed the cylinders with my rebuild, so I took mine around the block to see if a bit of break in would help it at all, and it didn't. It's ride-able, until you come to a stop, then it just dies.

My next course of action is to synch the throttle bodies and adjust the throttle position sensor. I'll probably do that this weekend, and I'll keep you updated. You really should synchronize your throttle bodies. When you adjusted the valves, you changed the amount of air that is flowing to each cylinder, so the previous settings aren't going to work as well as they did now that things are different; so you need to correct it for the new conditions.

I would suggest tripple checking for vacuum leaks as well; if you don't see anything, just grab a can of carb clean and make sure.

Setp one: Obtain 5-8 squares of clean, dry toilet paper.
Setp two: some prefer to neatly fold while others prefer the "wad" technique, but you need to condense the squares into a thicker unit of TP.

...do I really need to continue?
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post #3 of 5 Old 01-13-2011, 10:32 PM
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I revisited my top end and found that most of my valve clearances were off. I set them with the motor sitting on a bench, but never went back and checked them at operating temp. That was MY problem, hope that info helps you if you haven't figured out what's happening yet.

Setp one: Obtain 5-8 squares of clean, dry toilet paper.
Setp two: some prefer to neatly fold while others prefer the "wad" technique, but you need to condense the squares into a thicker unit of TP.

...do I really need to continue?
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post #4 of 5 Old 01-13-2011, 10:46 PM
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You don't adjust valve clearances at "operating temp". You should be adjusting at "room temp"- so it is more likely you inadvertantly fixed some other problem along the way of readjusting the valves.

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Stupid people say stupid things on the internet, so be wary of who those people are. If you solicit advice on the internet, just keep in mind 99% of what you'll receive is not based on fact or science-and likely atleast 95% of it is based on bullshit and bravado regurgitated from some other schlub who also did not experience any of what they claim and are also full of shit. If you don't like my bluntness- too bad. I am not here to please you, so move along, your approval is not desired nor is it needed. So before opening your pie hole and adding more stupidity, perhaps sit back, listen, absorb and learn something. You know that saying, it is better to remain silent and thought a fool than to open your mouth and remove all doubt!
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post #5 of 5 Old 01-14-2011, 03:27 PM
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Maybe theres a vaccum leak, or a disonnected sensor? one connected to the air box up front, or hiding. does it smell rich now?

"Those who sacrifice liberty (freedom) for safety, deserve neither."
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