K100 Won't start. Battery working. Aftermarket gauge with strange behavior

[LeMoeur]

Hello everybody!


Been here for some time, and always read the posts that indeed proved to be very useful to me.
I recently bought a K100 from 1992 (btw i'm in Italy) and trying to give him a new life with some shredding and customisation.
I started with changing the  headlight then moved to the instrument cluster (Koso RX2N). For this one I used some solutions found in this and other forums to enable the Null light and to get the "bouncy RPM" problem solved (low pass filter).


Last week i embarked for my first trip far from the garage, a city 50 kilometers from it, where i reside in the weekdays.
Before starting for the trip i noticed that with hot engine there was a strange issue: getting to high RPM (about 4k) with no gear and then letting the accelerator handle release fully would cause the bike to shut off... carelessly, i rode it, keeping in mind to release gently the accelerator, or keeping RPMs up before a full stop, and the problem never appeared again.


During the week i made quick trips around town and the only thing i could notice had been longer times (revving) to get the bike to start.


Just today, i started the bike as usual, it went on, then suddenly died out. I blamed not having opened the choke lever, retryied after that and it worked. 500 meters after, i stopped to make fuel and then the story got bloody.


Turning the key on start position would lighten the HUD, lighten the headlight, activate fuel pump (i can hear it whirring) but no sound on pressing the start switch. Instead, it goes lights out, like there were a huge power surge: gauge checks again as it would on key turning and fuel pump restarts. Then after few trials found a pretty unsettling thing (but this could well be my fault in connecting the new instrument cluster) when i pull in the clutch in the cluster starts up, same as it would if i had turn the key on.


Then tryed to solve the problem (thinking about flat battery) using a booster. I could hear the relay (starter?) clicking but no sign and no noise from the starter.


Even bump start didn't work: the bike would turn on... stay on for few meters then die out.

[/size]Now.. had to leave my bike unattended in a not so good block and now i really need help.[size=78%]


Thanks

[Laitch]

What is the battery voltage reading? You have made a good try at discovering the source of the problem.

Check the connection of the battery ground wire to the transmission. Is it clean and fitting tightly at both ends?
Check your positive connection to the battery. Is it clean and fitting tightly?
Check your fuel injection control unit plug. Is it clean and fitting tightly?
Check the connections to your starter. Are they clean and fitting tightly?
When this condition occurs, what happens if you turn the ignition key off and on quickly a few times then try to start it?
Have you checked the condition of the fuel filter and the tank hoses?
Do you have new, clean fuel in the tank?

The fault could be in the wiring of the new speedo but it could be somewhere else, too.

[LeMoeur]

What is the battery voltage reading? You have made a good try at discovering the source of the problem.

Didn't test it yet. I'll try tomorrow. And thanks... all my (little) knowledge comes from reading forums hehe.

Check the connection of the battery ground wire to the transmission. Is it clean and fitting tightly at both ends?

I didn't understand this tip... you mean.. the ground wire that goes from the battery to the transmission piece of the engine?

Check your positive connection to the battery. Is it clean and fitting tightly?

Checked, tight and clean!

Check your fuel injection control unit plug. Is it clean and fitting tightly?

Where is that?

Check the connections to your starter. Are they clean and fitting tightly?
When this condition occurs, what happens if you turn the ignition key off and on quickly a few times then try to start it?

Will try this tomorrow too.

Have you checked the condition of the fuel filter and the tank hoses?

The pump is new, shouldn't be the filter new too?  :dunno2:  the hoses seems good from outside.

Do you have new, clean fuel in the tank?

Fuel is new and clean!


Many thanks, I'll post any new that'll come out

[Laitch]

Didn't test it yet. I'll try tomorrow. And thanks... all my (little) knowledge comes from reading forums hehe.

You shouldn't undertake working on your bike without knowing the names of components and having a general idea of how they function but you went ahead and did it anyway. hehe Download a manual from this site's technical library.

I was referring to the battery ground wire connection from the battery to the transmission.
The fuel injection control unit is under the seat.
Maybe the fuel filter should have been replaced but there's no way of knowing unless whoever owned the bike before you knows or has records of its being replaced.
There are several electrical components that could be part of this condition and your wiring skill could be part of it, too.

How many kilometers has the bike been ridden? How many have you ridden it?

[LeMoeur]

Today i payed a visit to my beauty, and bringing with me my trustworthy voltmeter i tested the battery for charge... about 3V with the ignition key on OFF position and slightly more (that's strange!!) whit the key on ON. Now i charged the battery and i'm gonna reseat it tomorrow!

I was referring to the battery ground wire connection from the battery to the transmission.

Connected firmly.. I just added 2 other grounds to the bolt.. one for the RPM feed from the primary coil and the other one for some idiot lights added to the instruments (ex. Alternator light)

The fuel injection control unit is under the seat.

Seated & connected firmly!

Maybe the fuel filter should have been replaced but there's no way of knowing unless whoever owned the bike before you knows or has records of its being replaced.

That's unknownable, i fear

There are several electrical components that could be part of this condition and your wiring skill could be part of it, too.

I akwnoledged lately to have made a wiring error in the relay set i used to get the "N" signal
https://goo.gl/images/k8jxUo
I accidentally used the UNswitched power (the wire coming directly from the battery tonthe cluster) but i don't think that could have caused the mess... maybe only the battery drain

How many kilometers has the bike been ridden? How many have you ridden it?

I've made 250km (I know i'm a newbie..) the beast has about 45kmon her back!


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[LeMoeur]

In the end... i tried just recharging the battery at home and reinstalling it. It worked!
Didn't knew that low battery could cause the bike to not start even by bump starting.. i guess it's because the alternator it's not engaged at low RPMs


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[Laitch]

In the end... i tried just recharging the battery at home and reinstalling it. It worked!

:clap:

[LeMoeur]

:clap:

I feel so stupid and so happy at the same time!

Anyway thanks for your assistance!


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