Aprilia RS50 only jump starting (electrical issue?)

[dshwasher]

hi,

 

i last posted on here over a year ago. i have a little 2010 Aprilia RS 50 that refuses to start off starter and only will start when being rolled and put into gear (jump start). once she has been started like this, she refuses to start again once turned off (she needs to be jump started again). 

 

what i have replaced (from the top of my head):

 

(multiple) batteries

x2 starter motor

starter relay

CDI

stator

top end

 

i believe this is an electrical issue as when she is running, she runs no problem. the issue is, i am clueless when it comes to electrics. it would be greatly appreciated if someone could recommend some readings i can do. 

 

last thing, can someone please tell me what sort of voltage reading i should get between the battery and starter motor when cranking? the battery is healthy (over 12v)

 

thank you !!

Edited September 6, 2024 by dshwasher

[Tinkicker]

Electrical testing 101.

 

Disconnect the relay exciter wire ( small wire to relay) and touch a piece of decently sized wire between the relay exciter terminal and the battery positive.  If the starter spins, you have a problem in the exciter circuit, either a bad fuse, bad connection, bad ignition switch or handlebar switch.

 

Buy a cheap multimeter ( because you may damage a non pro type, specially designed for this type of testing, doing the test) and connect one end to the battery positive and the other end to the starter relay positive in terminal ( with battery cable fitted as normal). Set multimeter to amps.  Press the starter button.  If the multimeter shows zero amps, or very low milliamps during your test, it shows you have got good connections at each end of the cable and the cable itself is good.

If the multimeter stops working, you have blown an internal 10a fuse in the meter due to high current flowing through it, and the cable or connections are bad.  You could also before testing the cable,  first, test the connections at each end of the cable in the same way. Cable terminal to relay post and terminal at other end of the cable to battery post. If both show zero amps and then you blow the meter when testing the cable itself, you know you have a bad cable.

 

Repeat from relay to starter motor.  Then test the ground side cables and connections.  

 

 

Battery voltages. 

12.7 and im in heaven.

12.5 im still alive.

12.1.  Some work needs to be done.....

 

 

 

 

Edited September 6, 2024 by Tinkicker

[dshwasher]

hi tinkicker,

 

thank you for your reply. unfortunately i’m really clueless on this. i have a cheap multimeter. do i need it on the “10A” setting? i have attached a photo of it below (note that one cable is in the 10ADC plug, is this correct?). 

i probably should have mentioned that the bike does turn over. the starter is working but the bike still won’t start.

 

thank you for your help, i appreciate it!

[Tinkicker]

Ah I thought it would not turn over.  It sounds like the starter is taking too much of the available power from the ignition when cranking over then.

First place I would look is the ignition switch.  Does your neutral light go dim and flicker when cranking the engine over?

[RideWithStyles]

Are we talking of a carbs or injection bike?

[dshwasher]

id need to check tomorrow Tinkicker. i’ll report back with findings 

 

RideWithStyles- carb bike 

[Mississippi Bullfrog]

Just worth checking....if it's cranking over but not firing how old is the spark plug? 

[Thehunted]

If you are going to do any voltage testing, the red lead needs to go in the middle socket of your multimeter and leave the black lead where it is. Also the dial needs to go to 20v DC which is about 11 o clock on your tester. 

 

At the moment it's set up to test current.

[bonio]

But I think it's set up right for testing 10A through the start motor?

[dshwasher]

1 hour ago, Mississippi Bullfrog said:

Just worth checking....if it's cranking over but not firing how old is the spark plug? 

about a year old? i think i’ve had about 3 different spark plugs fitted and the issue persisted 

[dshwasher]

18 hours ago, Tinkicker said:

Ah I thought it would not turn over.  It sounds like the starter is taking too much of the available power from the ignition when cranking over then.

First place I would look is the ignition switch.  Does your neutral light go dim and flicker when cranking the engine over?

 

just gave this a shot. the neutral

light does dim and flicker but only very slightly. my bike has a battery voltage reading on the dash. according to my voltmeter i’m starting from 12.5v. when i start cranking, im getting 10.8-10.9. according to my bike however, im starting from 12.4v and when i start cranking im getting 10.1-10.3v. 

 

the readings you mentioned earlier, about the amperage. is it still worth giving them a shot. if so, can you confirm if my multimeter is correctly setup in the image i attached.

 

thank you

[Tinkicker]

No. The multimeter thing was to check the connection between the battery and starter motor.  If the engine cranks there is no problem.

 

You have a bad connection between battery and ignition module somewhere.  I found a wiring diagram online.  As an experiment, try disconnecting the yellow wire that goes from the generator to the voltage regulator and seeing if it starts then.  If something is sapping power from the ignition, then this should prevent it.

 

If not, check the connections of the green, red and white wires from the generator to the ignition module.

[dshwasher]

i tried disconnecting the yellow wire. i have the same issue. 

 

the green, white and red connections are in great condition along with the ignition module. they are both new and were replaced. 

 

i have tried to start the bike by connecting the battery to the starter motor via a jumper lead. same thing, turns over but never starts

[Tinkicker]

Sorry dshwasher.  I am out of ideas.... 

[RideWithStyles]

Carb, you could Try cleaning and I mean really clean the idle jet port/pathway. Most likely you’ll have to removed and strip them down and soak in carb or brake cleaner.

While your there might aswell look at the other ones. After putting it back together you’ll most likely have to rebalance it.

[Hairsy]

12 hours ago, dshwasher said:

i have tried to start the bike by connecting the battery to the starter motor via a jumper lead. same thing, turns over but never starts

One suggestion.
 

Can you do this but using a separate battery to run the starter motor, leaving the bike battery to run the ignition?
 

There was an earlier suggestion that the starter motor could be sapping so much power from the bike battery that there’s not enough power left to run the ignition. This would test that theory - I think it was a good one.

[Tinkicker]

1 hour ago, Hairsy said:

One suggestion.
 

Can you do this but using a separate battery to run the starter motor, leaving the bike battery to run the ignition?
 

There was an earlier suggestion that the starter motor could be sapping so much power from the bike battery that there’s not enough power left to run the ignition. This would test that theory - I think it was a good one.

 

 

According to the wiring diagram I came across, ignition module is energised directly by the generator, not the battery as was previously thought.  I figured that it had to be the battery dragging the generator down when cranking, hence trying with rectifier disconnected.

 

At a loss.  Only other thing, if everything else is clean and good, is the magnets in the rotor losing magnetism and the generator unable to supply sufficient power at cranking speeds.  Bump starting means higher engine RPM....

 

Loss of magnetism is a known thing for older 1970s two strokes with magneto ignitions.  I would not have expected it in a relatively modern bike though.

Edited September 8, 2024 by Tinkicker

[dshwasher]

these bikes have a rep for starting issues. i just cannot seem to get to the bottom of it. 

 

i have stripped down the carb before but i can give it another shot. 

 

i feel like its something so simple. something im overlooking. when i got the bike, it started perfect off the starter for the first day or so. i then serviced it and it stopped starting. she had been standing for a while so i did a battery change and oil/coolant drain and change. she started after all of that. then started refusing the next day. 

 

then again, maybe it was just horrible timing. 

 

thank you for all the help regardless 

[Nick the wanderer]

I had a Yamaha FZR600 which had this weird non starting issue. Most of the time it started on the button but every now and again it would just turn over and over and not start. Did my head in for ages looking at this and that, though I never tried bumping it.

Anyway in the end it was a wire to the generator where it went between the cases had just rubbed through. You couldn't see it until I took it off for a close up look, it must of shorted it out but only now and again.

Go through every wire to check the condition would be my advice, I know it's a ball ache but that's how I found that one for me.

Good luck.

[dshwasher]

yeah i think that’s my next move after i have a quick look at the carb. all the exposed cables that i can see look fine. there’s a few bundled cables (held together with like a sleeve). bit of a pain having to get the sleeve off and look through those cables but at this point i don’t know where else to look haha 

[Nick the wanderer]

I also noticed a Aprilia forum while having a quick look, maybe worth looking there if not already on it.

[dshwasher]

yeah i’m on there too. was a very lively forum last time i posted (around a year ago) but this time around seems a little quiet in comparison to the help i’m getting here hahaha

[David2025]

Did you manage to get to the bottom of this starting issue