Starter relay: I chose violence. It worked... but why? | GTAMotorcycle.com

Starter relay: I chose violence. It worked... but why?

adri

adri

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Recently got gifted a neglected 09 Ninja 250 that's been sitting in storage for a couple years (only 15k km ish).

Popped a battery in, no turning over, just a *click* sound whenever I hit the starter.

Battery voltage good, all fuses good, hmm...

I took out the starter relay on advice from a buddy. Then I'm not sure why, but I feel the need to whack the little bastard with a hammer. I put the starter relay back in, and she started cranking!!

Why is this? Was it the disconnecting and reconnecting of the starter relay, like turning the modem off and on again makes the internet work again? Was it the random act of violence? Why is it working again?

Trying to understand what my takeaway from this is, and maybe help others with no start issues in the future.

PS: She fired up with a little spray of brake cleaner in the air intake. I only let her run for a couple seconds. I want to drain out all the old fluids. And yup, I've ordered a replacement relay anyway, it arrives tonight.
 
It's not just the hitting, it's knowing where to hit and how hard. ;) ;) ;)
BTW - those things are notoriously cold blooded. A long time on the choke before you try a ride away. If any bike benefits from a jet kit these do.
 
adri said:
Recently got gifted a neglected 09 Ninja 250 that's been sitting in storage for a couple years (only 15k km ish).

Popped a battery in, no turning over, just a *click* sound whenever I hit the starter.

Battery voltage good, all fuses good, hmm...

I took out the starter relay on advice from a buddy. Then I'm not sure why, but I feel the need to whack the little bastard with a hammer. I put the starter relay back in, and she started cranking!!

Why is this? Was it the disconnecting and reconnecting of the starter relay, like turning the modem off and on again makes the internet work again? Was it the random act of violence? Why is it working again?

Trying to understand what my takeaway from this is, and maybe help others with no start issues in the future.

PS: She fired up with a little spray of brake cleaner in the air intake. I only let her run for a couple seconds. I want to drain out all the old fluids. And yup, I've ordered a replacement relay anyway, it arrives tonight.
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Look up a relay or solenoid teardown and it'll help put the pieces together. What may have happened is some moisture got inside and caused the armature or movable contacts to rust stuck. Violence just knocked the moving parts loose.

There's probably another ignition interlock relay that takes into account switch/stand/lever position, that might have been the click you were hearing. That relay would have to trigger before the starter relay.
 
adri said:
Recently got gifted a neglected 09 Ninja 250 that's been sitting in storage for a couple years (only 15k km ish).

Popped a battery in, no turning over, just a *click* sound whenever I hit the starter.

Battery voltage good, all fuses good, hmm...

I took out the starter relay on advice from a buddy. Then I'm not sure why, but I feel the need to whack the little bastard with a hammer. I put the starter relay back in, and she started cranking!!

Why is this? Was it the disconnecting and reconnecting of the starter relay, like turning the modem off and on again makes the internet work again? Was it the random act of violence? Why is it working again?

Trying to understand what my takeaway from this is, and maybe help others with no start issues in the future.

PS: She fired up with a little spray of brake cleaner in the air intake. I only let her run for a couple seconds. I want to drain out all the old fluids. And yup, I've ordered a replacement relay anyway, it arrives tonight.
Click to expand...
One of 2 things happened,

1) Stuck starter relay (normally called starter solenoid). This is an electro-mechanical relay. When you hit the start button, voltage goes to the trigger circuit (small wires) which energizes an electromagnetic solenoid. When the solenoid clicks, it's connecting the fat wires, one side to the battery and the other to the starter motor and the starter should spin. The mechanical part can stick or be intermittent for a variety of reasons, the click you heard indicates it was not sticking.

2) Corroded connection. This is more common, and since you heard the big click -- most likely. The trigger connections were working fine, firing the solenoid and giving you a solid click. A loose or oxidized connection on either fat wire is the most likely culprit, removing and retightening likely corrected this.

I doubt the solenoid is the issue, but it's a cheap part so changing it won't kill your wallet. Test the removed solenoid and toss it in the parts bin for future emergencies (they are very interchangeable). When you do change it, be sure to give the electrical connections a good clean-up and treat the connections to a little dielectric grease or Grote. Clean the fat wire connection at the starter too if it's easy to reach.

Sorry to say Fonzie, in this repair, the hammer whack was probably irrelevant.
 
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A common problem on older BMW K-bikes is a sticking starter relay which results in continuous cranking of the engine even if the ignition is turned off. The cause usually is a weak battery. The weakened battery is not quite strong enough to hold the starter relay closed and the relay chatters causing arcing. The arcing between the contacts causes the contacts to weld together. The "quick fix" is to strike the relay a blow that will release the contacts. That may have been what happened when you struck the relay.

Check your starter relay contacts for arcing damage and repair that damage by filing the faces of the contacts to remove arc-damaged metal.
 
My only experience with something similar was with my first car. The engine stalled for no reason and when I tried to restart it, it just cranked but wouldn't fire. I opened the hood to look around as if I knew what I was looking for, then slammed it down as hard as hard as I could in frustration and got back in. As I contemplated which direction to walk in the rain to get to a pay phone without an umbrella or jacket, I gave it one more try and it fired up immediately. Never happened again after that.
 
robmack said:
A common problem on older BMW K-bikes is a sticking starter relay which results in continuous cranking of the engine even if the ignition is turned off. The cause usually is a weak battery. The weakened battery is not quite strong enough to hold the starter relay closed and the relay chatters causing arcing. The arcing between the contacts causes the contacts to weld together. The "quick fix" is to strike the relay a blow that will release the contacts. That may have been what happened when you struck the relay.

Check your starter relay contacts for arcing damage and repair that damage by filing the faces of the contacts to remove arc-damaged metal.
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Welded starter solenoid contacts aren't the fault of a weak battery -- it's a design fault in the bike.

Whether the battery is weak or strong, a relay should not 'bounce' to the point where it welds itself closed.
 
Well, you may challenge my explanation, but it's what happens. Read about it in any of the BMW K-bike forums.

The starter relay has a pickup voltage (the minimum voltage needed to engage the relay and close the contacts) and dropout voltage (the minimum voltage required to keep the relay contacts engaged). A weak battery will show a significant voltage drop under load (like cranking a motor). The situation is that there is enough terminal voltage on the battery to meet the pickup voltage when the start button is pressed. The relay will engage and the starter motor turns. But the week battery can't deliver the needed current so its terminal voltage drops below the dropout voltage level. This will cause the starter relay to disengage. Then the current demand will disappear and the battery voltage will rise above the pickup voltage and the relay will engage again. And this cycle continues, many times a second. Meanwhile cranking current is flowing through the relay contacts (remember we have an inductive load with the starter motor and current drawn won't stop instataneously) and causing arcing each time the relay disengages, which heats up the contacts and eventually welds them together.
 
bitzz said:
How so? What "design fault"?
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Starter relays have been designed like this for decades, there was never a reason to fix something that wasn't broken.
They fail sometimes, so what ? Repair/replace and move along.
 
bitzz said:
How so? What "design fault"?
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A relay should never 'bounce' enough heat to weld itself together. Just because a relay can switch the amperage necessary to engage the starter in perfect conditions, the circuit still has to be reliability tested through a practical range of conditions. BMW chose the wrong part for the job, users found the dependability problem. Sound familiar?

Starter relays welding up was a common issue on Ks. BMW's first solution was complicated and silly -- add an additional relay into the trigger circuit that would not fire on low voltage. Later BMW dropped that idea and followed backyard mechanics by swapping the relay with the same $15 part used on large Japanese & American bikes.

Not a huge deal, but another example of where Euro makers put less into dependability engineering and testing.
 
TK4 said:
Starter relays have been designed like this for decades, there was never a reason to fix something that wasn't broken.
They fail sometimes, so what ? Repair/replace and move along.
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I think this was a fairly common issue on these bikes -- not the first time a bad design turned into a chronic problem. I have a couple of XV920Rs that are known for chronic design flaws in their starters.
 
Mike I'm not gonna argue with you about this but a low battery CAN weld starter relay contacts. If the battery doesn't have the amps to turn the starter, the voltage will spike and weld the contacts.
Pretty sure on the BMW starter relay the neg side of the coil goes to load, so the "cure" to a bouncing relay would be to give the coil a path to neg, but it will still weld the contacts if the battery is low.
 
bitzz said:
Mike I'm not gonna argue with you about this but a low battery CAN weld starter relay contacts. If the battery doesn't have the amps to turn the starter, the voltage will spike and weld the contacts.
Pretty sure on the BMW starter relay the neg side of the coil goes to load, so the "cure" to a bouncing relay would be to give the coil a path to neg, but it will still weld the contacts if the battery is low.
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No argument... it's pretty clear a low battery will weld contacts, the question is "Should that happen?" The answer is no, in a properly engineered circuit the contacts will not weld because the trigger will not fire if the voltage is too low to hold the contacts. W

Relays usually weld when the contacts get hot from arcing when they are bouncing.

In a low-battery situation, the voltage doesn't spike, it drops. As the voltage drops, the circuit closing the relay fails and the contacts open and then close quickly causing an arc at open and close. Repeat this in a machine gun cadence and the contacts weld.

The cure is to use a relay that will hold and not bounce under low voltage conditions. Holding the relay closed won't hurt -- the relay circuit resistance is only in the motor.

That's something that should have been detected in testing but clearly was not... for several years of production.





-- but only in a poorly designed circuit or
 
This inscription was found on the wall of a Roman chariot repair shop
It pretty much explains how the world works.

non opprimere
uti maior est malleo
 
Thank you all for the answers. Not gonna lie, I had to read some of them twice, slowly, and do some googling, to actually understand. Many thanks.

Sorry to say Fonzie, in this repair, the hammer whack was probably irrelevant.
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I see no reason to let your science dissuade me from my beliefs lol
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