Starts, rough idle, dies with throttle..

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aussie_rider59
Posts: 6
Joined: Thu Mar 07, 2013 4:31 pm
My Bike: Zxr400

Starts, rough idle, dies with throttle..

Post by aussie_rider59 »

Hey Everyone,

Newbie from Australia here. I bought a zxr400 track bike a couple of months ago which was running like a dream. I left my bike for about a month, went to start it and no love. The starter engine turned over but wouldn't turn the engine over. I replaced the battery, changed the fuel in the tank, drained the fuel lines and carbies. The bike now starts and idles (rough) but any pull on the throttle kills it completely. I'm guessing the fuel got old and went to crap and clogged up the jets?? Any thoughts?? Or does it sound like a vacuum leak? I don't know how that would happen when it was sitting though.

Cheers in advance!
Tess71
Posts: 3
Joined: Fri Jan 04, 2013 5:07 pm
My Bike: zxr400

Re: Starts, rough idle, dies with throttle..

Post by Tess71 »

i had this, turned out to be the fuel pump relay, so it got bypassed which alot of race bike do, and now it starts fine, make sure the fuel is on when you start it as when its not you will hear the fuel pump ticking over trying to suck fuel thro and keep it on reserve all the time, especially as its a track bike, but you knew that lol, i didnt, half way round snetterton!!
aussie_rider59
Posts: 6
Joined: Thu Mar 07, 2013 4:31 pm
My Bike: Zxr400

Re: Starts, rough idle, dies with throttle..

Post by aussie_rider59 »

Awesome thanks mate
aussie_rider59
Posts: 6
Joined: Thu Mar 07, 2013 4:31 pm
My Bike: Zxr400

Re: Starts, rough idle, dies with throttle..

Post by aussie_rider59 »

Umm Tess, mind explaining the tech behind this? If there is a faulty relay does that mean its telling the pump to stop operating when it really should be?
aussie_rider59
Posts: 6
Joined: Thu Mar 07, 2013 4:31 pm
My Bike: Zxr400

Re: Starts, rough idle, dies with throttle..

Post by aussie_rider59 »

I can hear my fuel pump feed as soon as I turn on the electrics before I hit the ignition. I'm guessing that means its already bypassed.
Tess71
Posts: 3
Joined: Fri Jan 04, 2013 5:07 pm
My Bike: zxr400

Re: Starts, rough idle, dies with throttle..

Post by Tess71 »

the tech is right and yes if you can hear it ticking when the fuel is in the off position then yes it sounds like its already bypassed, alot of race bikes do this. i have had so many issues with mine with the fuel side of things, which first occured like your self when i let it stand for 3 weeks to respray bodywork, put it all back together then she wouldnt run without the choke on full, the removal of relay sorted that, then took out on track and she was faultering on full gas, turns out the regulator rectifier was shot so you may have to check all of this too, i am also giving her a complete carb rebuild to and a new throttle cable! sounds small but they wear badly and dont return very well, these are 20yr+ bikes after all! but im still to test it out on track yet so watch this space, good luck
aussie_rider59
Posts: 6
Joined: Thu Mar 07, 2013 4:31 pm
My Bike: Zxr400

Re: Starts, rough idle, dies with throttle..

Post by aussie_rider59 »

Ok I feel like such a douche, pulled the carbies apart and cleaned the jets out (clean as a whistle so there was no point). Put it all back together again and noticed a wire had fallen off from the right coil! Duh! Oh well at least my baby is running like a champion again!
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