1992 Katana 750 dies unexpectedly while riding

[69396Chevy]

I am posting this for a friend who does not have internet access during the day from work. Hopefully someone can help us figure out what's wrong with this. I'm pretty good with cars and thinking this is some sort of electrical problem but cant diagnose it unless it dies. My thinking was follow him around until it dies then pull the tank off and check for power to and from the coils, spark and maybe the CDI or ignitor as its called in the manual, remember Im not a bike guy so excuse the wrong terms.

It's a 1992 750 katana
It has a full Yoshimura 4 into 1 pipe, a "Factory Pro" jet and needle kit,
and Accel super coils with 8.5mm plug wires.

I have tried all the fixes that were mentioned for the GSX1100(Checking the vacuum line to the carbs from the tank and riding it with the gas cap off or loose to make sure it is venting).

It will idle all day and can be revved to redline repeatedly with no stumbles or any other problems but within 5 minutes of road riding it will
shut off completely. It shuts off as though the ignition switch was turned
off, even though the lights are still on and it will crank over with no
spark.

After waiting approximately 3-4 minutes it backfires loudly and starts. It will then run (riding) for approximately 1-2 minutes before shutting off again. If it is restarted, (without riding) it will idle indefinitely again.

This is what we have already tried:

1.) replacing the CDI. (identical results)
2.) synchronizing the carbs (found that i had no vacuum reading on the 2 RH carbs, but both LH were fine) bike IS running on all four cylinders with
good throttle response.
3.) all previously mentioned possible fuel delivery problems (open tank
cap, petcock set to reserve, petcock set to prime)

I can take the bike out in the street and do 60 ft burnouts repeatedly, but
I can not ride it in a normal fashion for more than 5 minutes.

Anyone have any ideas??

[Motorcycle Forums]

MotorcycleForums.net is the original Motorcycle Forum! Registered Users do not see these ads. Please Register - It's Free!

[timekills]

Wow. It's like a "try before you buy" bike. You can get a taste, but can't use it for real unles you pay first.



I'm such help, aren't I?

[Fosters99Katana]

Its a long shot but I know my Katana has a touchy kick stand. Any decent bump will jar it enough to kill the bike.

[87gsxrnut]

Yeah, no spark could inticate either sidestand or clutch kill switch. Also try cleaning the kill switch/connections by the throttle. Those damn Suzuki kill switches have caused all kinds of misery over the years for me.

- Nut

[69396Chevy]

Weve cleaned the kickstand switch but havent ridden it yet, also what do prople do with "the secondary air cleaner hose" when they get rid of the factory airbox? can it be plugged?

[87gsxrnut]

Are you talking the one that comes off the top of the valve cover?

If so, you can do the following:

- Route a hose through the bodywork and have it come out the rear of the bike. Cap it w/a filter.

- Route the hose under the tank and cap it w/a filter. Not recommended because oil fumes make a mess in there over time.

- Route it to a catch bottle. Not really necessary for the street, but works OK too.

Do NOT plug or cap it off however. This is the crankcase vent. If you plug it, the oil will find its way out somewhere.

- Nut