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Discussion Starter · #1 ·
Hello all, my names damian and im new to the forum.

So i recently aquired a 2002 zx12r with roughly 14k miles, the engine build seemed pretty extensive, je +3mm pistons, built/ported head, cam gears, nitrous, air shifter, myrtle west swingarm, pc3r, msd launch control, etc etc

the bike starts up cold just fine, little hesitation, but after maybe one or two cranks (@35 degrees) she fires up and idles great. once she is up to temperature i will have slight hesitation from idle to 2500-3krpm then she starts pulling wonderful.

my problem is when this bike is at normal operating temperature i will shut it off, go to start it again and it will chug slower than normal like a bad battery almost, or like the ignition timing is too far advanced. But if i let the bike cool down it will start up no problem. today while trying to do some diag i was riding it around the block a couple times and temp got to about 3/4 and then as i was about to shut it off the fans kicked on.

This is driving me nuts trying to figure it out, battery, rectifier, stator are all new and wired correctly.

so heres a question, this problem leads me to advanced timing possibility, too advanced keping it from being able to hot start

Does the coolant temperature sensor have anything to do with timing or fuel on these bikes, is there a diag procedure to test these on the bike (resistance values etc)

the bikes tune is a mess on the power commander 3r, and in cell 0% throttle 500rpm it shows a fattening of 5, which doesnt seem normal to me. i dont want to erase the map and start over, but if i was to post the map would someone be able to tell me if it looks right on a larger bore zx12?

i apologize for the long post but im trying to provide as much info as possible for you kawasaki gurus to shed some wisdom on me, wanted to say thank you in advanced and i hope i can find the answers to my woes.
 

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2003 Kawasaki ZX-12R
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I was going to be installing an afr gauge, sooner than later. I haven’t yet.
My idle is fine, it just won’t start when hot, that’s my main concern
Well if the bike can't start when hot then the idle is most likely also not good while hot, you did state it would "chug" while hot. Having a wideband Guage can help to determine whether maping is one of the issues. Also, have you checked your coils and plugs? Coils can sometimes perform worse under hot temperatures, and it's free to check them as long as you have a multimeter. As for your mapping i personally never touch anything below idle (1000-1500 my bike) or the 0% throttle column however my engine is not as moded as yours, some of the more experienced 12 owners here on the forum would be the ones to know as wether that is normal given your build.
 

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Discussion Starter · #6 ·
Well if the bike can't start when hot then the idle is most likely also not good while hot, you did state it would "chug" while hot. Having a wideband Guage can help to determine whether maping is one of the issues. Also, have you checked your coils and plugs? Coils can sometimes perform worse under hot temperatures, and it's free to check them as long as you have a multimeter. As for your mapping i personally never touch anything below idle (1000-1500 my bike) or the 0% throttle column however my engine is not as moded as yours, some of the more experienced 12 owners here on the forum would be the ones to know as wether that is normal given your build.
By chug I meant it would turn over very slow, imitating a bad battery or too much advanced ignition timing. Whereas when the bike is cold (before running it and after running it and letting it get back down in temperature) it starts up very swiftly with no hesitation. I agree that I need to get an afr reading. And would make sense to have a gauge on the bike as a permanent fixture.
But to clarify, it has all new plugs and coils, as well as battery, stator, regulator/rectifier, and high torque starter.
 

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Does it have a manual timing advancer ? Pull the crank trigger cover on the right side to see.

disassemble the starter and check the brushes?

86mm pistons may be 13:1 compression. Do you have a battery with enough amperage?

does the crank have added stroke? To tell quickly, is there a large spacer/shim between the block and case?

what are the cams degreed to? What cams are being used?

have you checked the starter solenoid, cables and ground? No corrosion

Handle bar start switch needs to be clean and make sure all the contacts are good.

when it’s hot, use a regular car battery and jump start at the starter. This will provide plenty of amperage. If it spins and starts then you know you need a stronger battery?

just some things to check.

cmg
 

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Just a comparison. My 1361 zx has bigger bore and stroke. Timing is advanced in the ecu. (Scott Davis flash) no advance down low. 415”/265° cams
13:1

starts fine when hot. I am using a AG801 240 amp battery. All cabling and switches are stock. Made sure the battery box connections are clean and tight.(I did bypass the ignition with a woodcraft zx14 ign delete)

cmg
 
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