I’m hoping the gurus can help with a starter fault that I’m experiencing on my 85 R80 RT.
When attempting to starting off a fully charged battery I get a few clicks, occasionally a turning over of the engine but then she dies. It’s draining the battery down to 9v while and switching off.
The bike has a new motogadget m-unit setup, however I was experiencing this just prior to the rebuild. Battery is relatively new, and I’m confident it’s not a wiring/grounding fault. Was thinking it could be a faulty battery, faulty starter motor, cooked diode board or faulty alternator.
Is there any other possible causes, and how do I go about isolating which of the above is the guilty culprit?
Thanks in advance.
Starter Troubleshooting
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Rob Frankham
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Re: Starter Troubleshooting
OK, there are four real possibilities here... starting with the most probable.
1) The battery is shot. Yes, I know it's relatively new but your statement. Don't really understand your statement 'It’s draining the battery down to 9v while and switching off.' but if the battery is falling to 9v when the starter is engaged and not recovering as soon as the load is removed then the battery is definitely suspect. As a first port of call, you can get the battery load tested at most auto electrical shops toalternator be sure.
2) The problem is caused by a defective starter. An '85 RT would probably be fitted with a Valeo starter. If it is the original, then there is a very real chance that the permanent magnets in the starter have come loose. Often this will completely jam the starter but this doesn't appeared to have happened here. If they are loose but not jamming the motor, the result can be a motor that drains energy but produces virtually no power. Remove the starter cover. Look at the rear of the starter solenoid, there are two large nut connectors. One has the BIG lead from the battery, the other has a braid leading into the motor proper. Us a piece of substantial wire to briefly connect the second connector (the one with the braid) to battery positive. If the motor spins freely, it's probably OK
3) The starter solenoid is corroded. To check this, you really need to remove it from the motor and dismantle it.
4) There is an interuption in the main power circuit to the starter. Check battery terminals (undo clean and refit... a terminaol that looks and feels secure can still be bad if there is corrosion b etween the connector and the terminal. Do the same for the end of the main cable on the starter. Check the main battery ground at the rear of the gearbox. Check that there is not a build up of corrosion where the starter seats on the crankcase.
The fifth possibility that doesn't really bear thinking about is that engine itself is partly seized... remove the front cover (don't forget to disconnect the battery) remove the spark plugs and try to turn the engine over with an allen key in the stator bolt. You should be able to turn it fairly easily with just a short allen key.
Finally, you can discount the diode board and the alternator. They don't affect the operation of the starter as long as the battery is fully charged. Not saying they are necessarily good but they are not the cause of this issue.
Rob
1) The battery is shot. Yes, I know it's relatively new but your statement. Don't really understand your statement 'It’s draining the battery down to 9v while and switching off.' but if the battery is falling to 9v when the starter is engaged and not recovering as soon as the load is removed then the battery is definitely suspect. As a first port of call, you can get the battery load tested at most auto electrical shops toalternator be sure.
2) The problem is caused by a defective starter. An '85 RT would probably be fitted with a Valeo starter. If it is the original, then there is a very real chance that the permanent magnets in the starter have come loose. Often this will completely jam the starter but this doesn't appeared to have happened here. If they are loose but not jamming the motor, the result can be a motor that drains energy but produces virtually no power. Remove the starter cover. Look at the rear of the starter solenoid, there are two large nut connectors. One has the BIG lead from the battery, the other has a braid leading into the motor proper. Us a piece of substantial wire to briefly connect the second connector (the one with the braid) to battery positive. If the motor spins freely, it's probably OK
3) The starter solenoid is corroded. To check this, you really need to remove it from the motor and dismantle it.
4) There is an interuption in the main power circuit to the starter. Check battery terminals (undo clean and refit... a terminaol that looks and feels secure can still be bad if there is corrosion b etween the connector and the terminal. Do the same for the end of the main cable on the starter. Check the main battery ground at the rear of the gearbox. Check that there is not a build up of corrosion where the starter seats on the crankcase.
The fifth possibility that doesn't really bear thinking about is that engine itself is partly seized... remove the front cover (don't forget to disconnect the battery) remove the spark plugs and try to turn the engine over with an allen key in the stator bolt. You should be able to turn it fairly easily with just a short allen key.
Finally, you can discount the diode board and the alternator. They don't affect the operation of the starter as long as the battery is fully charged. Not saying they are necessarily good but they are not the cause of this issue.
Rob
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Riverman0000
- Posts: 4
- Joined: Tue Feb 06, 2024 7:45 pm
Re: Starter Troubleshooting
Thanks Rob, that’s very helpful.
I’ll try using my car battery first, things tick those steps off. Fingers crossed.
I’ll try using my car battery first, things tick those steps off. Fingers crossed.
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Riverman0000
- Posts: 4
- Joined: Tue Feb 06, 2024 7:45 pm
Re: Starter Troubleshooting
Fires up beautifully with the car battery connected via jumper leads. Hopefully it’s just a faulty battery. Will replace and fingers crossed, problem solved
In hindsight the car was running, assuming I should check if it fires up with the car engine off as well before jumping the gun?
In hindsight the car was running, assuming I should check if it fires up with the car engine off as well before jumping the gun?
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Rob Frankham
- Posts: 1213
- Joined: Thu Aug 26, 2010 2:11 pm
- Location: Scotland UK, 20 miles from civilisation up a dead end road!
- Contact:
Re: Starter Troubleshooting
No, if it fires from a jumped battery, whether the donor vehicle is running or not, then the fault is probably the battery. A simple test for the battery would be to charge it fully (off the bike) then leave it for - say - 6 hours and check the terminal voltage... should be somewhere over 12 volts. If it's below that, then the battery isn't holding a charge... ie. it's shot. If it does hold it's voltage, try it on the bike. If it won't turn the bike over (or even if it's sluggish) the battery is shot. If it does start the bike then treat it with caution... leave it for a day and try it again.
It's worth disconnecting any clock and/or other permanently connected electronics during this time.
It's also well worth checking (or having checked) the charging system. If it's not performing to spec, it could be putting an additional strain on the battery which might be contributory to early failure...
It's worth disconnecting any clock and/or other permanently connected electronics during this time.
It's also well worth checking (or having checked) the charging system. If it's not performing to spec, it could be putting an additional strain on the battery which might be contributory to early failure...