zx9r c2 intermittent starting problem

[trevor saxe-coburg-gotha]

Eh up everyone -

My bike's a C2 with 85k on it and runs and rides very well. But for the last couple of years it's developed a fault when starting. This happens hot and cold, but ironically does seem somewhat less prone in winter (!).

Symptoms are: key in barrel, turn key, thumb starter, cranks but yet I know - I just can tell - it's not going to fire up. My usual cure is simply to turn the key back to off, and then back to start, and this one simple thing is 90% of the time enough to correct the starter system and the bike fires up as it should do - almost instantly.

This problem arises on or off choke.

Lately the problem's increased in regularity and developed a couple of new twists. Firstly, it'll do it four or five times in a row before it "corrects" itself with the key-back-to-off 'trick'. Secondly, it's starting to sound like the battery is shagged when it fails to start.

Now you're going to ask me how old the battery is. I can't tell you for sure. What I can say is I've owned the bike for - what - let's say 4 years. I haven't fitted a battery - I don't think there's a receipt for one in the stuff from the previous owner. Bike had 18k on it when I bought it - which to me suggests it HAS stood underused - which in turn implies it will have had a battery unless it's been Optimated. So I don't know is the short answer. It could be the original though. Me, I run the bike couple hundred miles a week on average, throughout the year.

note - despite not being EFI, this bike has a CPS, it's conjectured that KAwasaki were going to make the switch to injection but delayed it for whatever reason - but regardless, could some sort of CPS problem give the symptoms I'm experiencing?
____________________
"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[jaffa90]

I would be checking if the fuel pump is activated when switching on .

[to v or not to v]

putting new plugs and plug caps in mine greatly improved the cold starting.
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current bike Yamaha Thunderace.
Moto Guzzi V7.

[Irezumi]

Are the key and lock/barrel set original. Sounds stupid but could it be worn and moving from on to off slightly?

Long shot but not unheard of.

[Kawasaki Jimbo]

I was thinking the same since the lock on my similar vintage, 66k miles 6R is noticeably worn and I can pull the key out in the ON position. However I don’t have any running problems, and would a worn barrel allow the starter motor to work but not the ignition?

[Copycat73]

I've had bikes spin with the kill switch off.
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Whatever I post I have no citation and no intention of providing one..
caveat emptor

[UncleFester]

If wiggling the key is what sorts it then i'd be looking at ignition barrel / wiring and also cleaning the kill switch / starter with dielectric white grease.

That said, 'her' CB400SF will spin over all day long on a half charged battery but will start every time without fail on a fully charged one. It was even more iffy before new plugs. So now it has new plugs and lives on an Optimate and has given no more trouble.
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2017 Z1000SX

[trevor saxe-coburg-gotha]

tbf i've probably got 85k on these plugs
____________________
"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[jaffa90]

[trevor saxe-coburg-gotha]

[xX-Alex-Xx]

[trevor saxe-coburg-gotha]

i wonder how it actually would run on 85k plugs though
____________________
"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[xX-Alex-Xx]

[trevor saxe-coburg-gotha]

https://media1.tenor.com/images/de3f46ffff16213a116b4cdd0be97e96/tenor.gif?itemid=17599743
____________________
"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[Robby]

My first thought was a sticking relay, but I don't know if there are any relays that would cause this problem in your system.

It runs carbs, so any fuel pump stuff is not a factor in initial start. The float bowls will have fuel in, so it has fuel.

The engine is spinning over, so the bulk of the electrics are behaving.

This means that something is intermittently interrupting the spark, and only on startup, not when running. A sticking relay is the neatest problem, could also be a corroded connection giving high resistance and not enough power to create a spark while also running the starter motor.

Wiring diagram, look for anything that can interrupt the spark from the ignition barrel down.

[trevor saxe-coburg-gotha]