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I need help with my st

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mark d
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I need help with my st

#1 PostAuthor: mark d » Fri Dec 28, 2018 8:40 pm

Got a problem .my st has been in the family from new so it’s 99% original and std as from the factory : I went to use it at the start of last summer and I found it seemed to shut down at about 3.5 thou revs I could shut of the throttle and re twist and it would pick up again only to shut down as if it had a rev limiter fitted . I’ve stripped the carbs down twice and made sure there were no blockages , I also noticed the coils were split so I put on new ones from z power , ive checked the wiring but I can’t find any loose or damaged parts. I knew I had a seized spark plug in no 2 cyl which I snapped trying to get it out ( to put in a new set ) I’ve had my mate an x Kawasaki mechanic from the zed days sort the head and now 6 months later I’m testing the bike and it’s shutting down again ( I can rev the bike high on a stand still ) does any one have any ideas ? Could the std electronic ignition cause this ? Or the cdi ? Now up to these revs it’s as sweet as can be and rides like there’s no fault until you get to roughly 3.5 depending on what gear your in . Any help would be gratefuly appreciated before I start buying parts for it . And getting my mate away from his really busy schedule is a waiting game and I want the bike to be ready . Thanks mark
4 pipe a1, z1000 st ,gpz rx 1000 x3 , Rx bitza in boxes x1

garyd
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Re: I need help with my st

#2 PostAuthor: garyd » Fri Dec 28, 2018 10:19 pm

As you've looked at the carbs, I wont suggest that.

have you thought that the air vent to the tank might be blocked? this could cause the fuel to flow slowly...enought to stop it reving.

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chrisNI
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Re: I need help with my st

#3 PostAuthor: chrisNI » Fri Dec 28, 2018 10:56 pm

+1 to checking that, also check the fuel tap isn’t surrounded with a layer of crud inside the tank, and just to double check - when you did the carbs you did check float levels?

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Re: I need help with my st

#4 PostAuthor: Philippe » Sat Dec 29, 2018 5:40 am

Hi Mark
a suggested above, check the fuel vent in the filler cap. To determine if that's the problem take a ride with the fuel cap open so air can get in the tank, be sure there's only the half amount of fuel in the tank so it doesn't get out on top while riding it.
The same happened to my Z1R. A blocked fuel vent hole. She would ride, but when revving up the engine, she stalled. There was no problem with a full fuel tank as the fuel warmed up by the engine heat, thus creating an over pressure and forcing the fuel to the carbs. When I filled the fuel tank the temperature of the fuel inside the tank dropped and the overpressure was gone until the fresh fuel was warm enough to create more pressure to get the fuel running again.
Good luck !
GrtZ
Philippe
the differences between a little boy and an adult man is the price and size of their toys!

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gpjes
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Re: I need help with my st

#5 PostAuthor: gpjes » Sat Dec 29, 2018 11:27 am

Process of elimination, fuel & flow, get a remote fuel bottle blank off the vacuum tap feed and run it that way, if it sorts it well fum and games but curable, however, if the problem is still there,,, cdi, or check the bobweight assembly advancer RH side, ST's do run to stupidly high mileages std, which was what they were designed to do :D
More Smiles Per Mile

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Al
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Re: I need help with my st

#6 PostAuthor: Al » Sat Dec 29, 2018 12:00 pm

If the coils cracked i would have a look at the ballast resister. If it has failed / overheated you could measure the voltage at the battery at 3,500 RPM and if high then it may have fizzed the CDI.

AL
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mark d
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Re: I need help with my st

#7 PostAuthor: mark d » Sat Dec 29, 2018 12:35 pm

Thanks I will try these suggestions over the next few days . One other thing that happened and this was in 2000 on a z rally that the wires from the electric ignition side (points side if it had points ) melted on the exhaust and kept miss firing / shutting down higher speeds which I fixed with tape and double checked it the other day by soldering the joints for a solid connection and I’ve had no problem since then until now ( I wrote in the mag on look before you strip down the carbs ) I wonder if this knackered my coils etc . I will def try the easy options of air flow first and get back to you
Thanks for the information your a great bunch
Mark
4 pipe a1, z1000 st ,gpz rx 1000 x3 , Rx bitza in boxes x1

garyd
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Re: I need help with my st

#8 PostAuthor: garyd » Sat Dec 29, 2018 4:12 pm

Not sure I like being called a ' great bunch'

mark d
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Re: I need help with my st

#9 PostAuthor: mark d » Sat Dec 29, 2018 5:13 pm

Sorted my shaft drive out and it turned out to be something so simple I had only gone and put the air filter in the wrong way round and don’t I feel stupid but glad it was an easy fix .thanks to all who said about air flow . Took the bike out and she is super smooth and quick , with out this club help I could of spent hundreds so it shows how much it’s worth being in the club and I would gladly pay double for all its help . Now looking forward to summer
Thanks
Mark
4 pipe a1, z1000 st ,gpz rx 1000 x3 , Rx bitza in boxes x1

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gpjes
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Re: I need help with my st

#10 PostAuthor: gpjes » Sat Dec 29, 2018 5:22 pm

I wouldn't worry about the little disasters, all part of growing up, we live and learn, you have used cdi type coils, I have to ask coz I hate to think it, but saw it done when I worked at bike shop back in 86 ho ho, yep gone are the days of charging a condenser up in the sparkplug cap, and throwing it across workshop to the current smallie and shouting CATCH, Ahh yes the good old days :twisted:
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chrisNI
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Re: I need help with my st

#11 PostAuthor: chrisNI » Mon Jan 07, 2019 10:56 am

mark d wrote:. One other thing that happened and this was in 2000 on a z rally that the wires from the electric ignition side (points side if it had points ) melted on the exhaust and kept miss firing / shutting down higher speeds
Mark


That must have caused a bit of head scratching... :D

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