Evo 1340 Solenoid run on

McQ

McQ

Registered User
Only just got your message reply.
I put a post up about a problem with my 85 Evo1340 FXWG, When the battery has been sitting idle without the optimate plugged in it has this problem with the starter solenoid, in that it turns over ok at first, but if it doesn't fire before running down, it then goes into what's called a run over cycle, where even if the ignition is switched off it continues to turn over putting lots of pressure (heat) into the battery, this normally goes until the next full cycle and is ok. But sometimes it jams and then keeps going until something gives, i.e. no power left in the battery or what happened to my Motobatt (barely 4 months old) It blew it up. because it has a Horseshoe oil tank with battery inside, It's not just a quick undo. The thing is every time I have asked any Harley service place Official or Unofficial about this, they just say keep it topped up with an Optimate it'll be fine, Which is ok, But it isn't a solution...
The other day I was looking at google, and happened on an article whilst searching for info on exhaust fitment, which mentioned this problem and they had called it Solenoid run over mod, On the Harley Davidson Forum, (USA I think) so i read it up and there is a wiring solution the guy was demonstrating in pictures, But it was for the old style mechanical relay and regulator, mine is transistorised, So I was wondering if anybody on this site had heard of it or even done it to their bike, Or knew how to sort electrics on bikes? I would like it done and am pretty hands on but just wanted to make sure about which wires go to where. so if anyone on here could help that would be brilliant, and if I could help anyone with what I can do, Welding, Fabrication (to a point!) I can work things out, But not always able to make the part's, Mainly trial and error with me, I like to use stainless where I can too! I am pretty good at sourcing stuff.
The wife say's because I am too stubborn to let anything beat me.. Lol
 
I had a problem with the starter running on occasionally and I cured it by taking the solenoid apart and giving it a clean.
I also gave the spring a stretch.
Doesn't cost anything to try it.
 
Basically you already have the answer, if the bike is fine when being on the Optimate and the problem only happens when it has not, the battery has insufficient capacity to start the bike!

Yes I have had the issue where the starter keeps running, with similar set up with a sperate solenoid & starter motor, if it keeps running until the battery goes flat at best it will destroy your battery fairly quickly or the battery could basically explode due to overload!

Generally why the starter keeps running is not the solenoid contacts are stuck but due to the engine not starting. The engine does not start because there is insufficient voltage to get a decent spark as the volt drop caused by the starter motor drawing around 100 to 150 amps to run the starter will drop the voltage, this is where it comes back to the Battery having insufficient capacity!

However it may not be just as simple as a new battery, it could be one of several issue or a combination of a few or all!

The solenoid wiring mod is most likely where people have replaced the original large round starter relay with a small square one as used by later bikes and cars, you have to re-route some of the starter cables and solenoid cables to do this!
If I find the pictures I will stick it in below!

Early
1707497480848.png




Late

1707497537202.png


Why the starter motor keeps running:

Basically more mechanical rather than electrical.

Press the 'Start' switch, this operates the relay which makes the circuit for the solenoid pull in coil, the solenoid pulls in engages the starter drive gear on the clutch ring gear and makes the circuit for the starter motor to run, as well as switch the solenoid from 'pull in' to 'hold in' coil.

The starter motor turns the engine over and this turning starts the ignition circuit regards sparks at the right time, the motor starts, you release the start button, the relay releases, the solenoid circuit breaks the hold in coil circuit, disengages the solenoid which then breaks the starter motor circuit and the drive gear disengage with the ring gear, fine.

If the engine does not start and the drive gear is a bit tight on the ring gear, the bush for the starter shaft worn, solenoid spring a bit weak etc. the drive gear may stay engaged even when the solenoid circuit is broken, if it stays in it will keep the starter motor circuit made as it is a mechanical connection.

Why in this condition it works fine if it starts & not if it does not start is to do with the engine running faster than the starter motor can turn and throw the drive gear out, the same if it stalls or kicks back, the jolt will tend to throw the starter gear out.
If it happens you can try putting it in gear, this may give enough jolt for the starter gear to be thrown out!

The starter can keep running if you try to start a bike without the outer primary on as the starter shaft will not be supported and can get stuck in!

So basically when I had it happen, it basically came down to the solenoid, required replacing, rebuild kits, only worked for a short while, I tried H-D, Eagle Iron, Accel, kits, even had the starter motor fully tested!

I mentioned there could be various other items that will limit the battery capacity to start the bike, these will all be basically to higher resistance than they should be, it does not take much resistance to make a difference as you need around 100 to 150 amps for the starter.

Start simple, check the battery & starter connections, they should be clean & tight, no corrosion. This should include all the earth connections in the starter circuit, especially the main earth to the motor/frame connection.
Check the cables, are the lugs cracked, are there green/blue deposits on the cables, if so you want to replace them.
Is the solenoid cap cracked, if so this will let moister in and corrode the terminals for the starter.

Then look to checking/replacing the battery, strip the solenoid, check replace the return spring.
Then if you want to go further, check the starter shaft bush is not worn or even missing in the outer primary, check the ring gear and starter gear, even the clutch bearing and primary alignment!
 
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nealebms said:
It sounds like the contacts in the starter solenoid are temporarily sticking welding themselves together, I may be wrong but have seen it.
Click to expand...
No it's been replaced three times, I am now running an all balls one as recommended these have better resistance.
 
This is the wiring diagram the Guy from America sent me,

But when I went to check it out, I found whoever had done the wiring (Import from States bought during Covid as a project) had renewed the plug for the original Starter relay and had got two wires the wrong way round, which meant unbeknown to me, because it was working, The relay was in fact permanently on, causing the battery drain problem, and the run on as it kept the solenoid energised too... a quick swap round with the earth and power wires, Fingers crossed, It won't need the mod done! I wish that one of the Harley experts had checked that out, When I first said about it... But then again I could blame myself too, But it's not something that you would expect to check really....





1707571493875.png
 
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If that is how it is wired you have a relay operating another relay, which is unnecessary!

Have you still got the H-D large relay as below, if so you do not need it, it itself will add extra resistance & high current carrying contacts!
1707659455081.png

Basically you replace that round relay with the Bosch type and change the wiring as below, so the Bosch relay is operated by the starter button & the heavy duty contacts of that relay operate the solenoid.

The solenoid is connected direct to the battery Positive and direct to the starter, so there is only one set of contacts from the battery to starter motor. No link wire is required on the solenoid as it is connected direct to the relay.

Basically as below

Starter.jpg
 
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Whoever came up
McQ said:
This is the wiring diagram the Guy from America sent me,

But when I went to check it out, I found whoever had done the wiring (Import from States bought during Covid as a project) had renewed the plug for the original Starter relay and had got two wires the wrong way round, which meant unbeknown to me, because it was working the relay was permanently on, causing the battery drain problem, and the run on as it kept the solenoid energised too... a quick swap round with the earth and power wires, Fingers crossed, It won't need the mod done! I wish that one of the Harley experts had checked that out, When I first said about it... But then again I could blame myself too, But it's not something that you would expect to check really....





View attachment 1199587
Click to expand...
Whoever came up with this idea is not an Auto Electrician. As SJC says, all this does is add another Relay to operate a Relay. Totally pointless.
Do what SJC says in his post and you will not go wrong. 👍🏻
 
SJC69 said:
If that is how it is wired you have a relay operating another relay, which is unnecessary!

Have you still got the H-D large relay as below, if so you do not need it, it itself will add extra resistance & high current carrying contacts!
View attachment 1199601
Basically you replace that round relay with the Bosh type and change the wiring as below, so the Bosch relay is operated by the starter button & the heavy duty contacts of that relay operate the solenoid.

The solenoid is connected direct to the battery Positive and direct to the starter, so there is only one set of contacts from the battery to starter motor.

Basically as below

View attachment 1199602
Click to expand...
Thanks mate, As I said when I actually went to look at my relay, It turned out the owner in the USA had wired up the plug wrong on the Bosch type conversion (It should have had the old bolt on style). He had the Ignition and main breaker wires the wrong way round, Which was keeping the relay on with or without ignition, which caused both problems, The battery drain and run on... The only bit different on the wiring to your diagram now is that 85 & 86 are the opposite way round, but when I looked up on google it says that shouldn't matter as long as it's opposite, Is that right, or do I need to change them over too?
 
softail898 said:
Whoever came up

Whoever came up with this idea is not an Auto Electrician. As SJC says, all this does is add another Relay to operate a Relay. Totally pointless.
Do what SJC says in his post and you will not go wrong. 👍🏻
Click to expand...
Hi mate,
Thanks for the reply, I haven't actually done the conversion, But was just asking if anybody had heard of it, As I was at my wits end, trying to sort this problem out. because it kept doing these problems, I was holding back from riding it much... I've had three different mechanics work on this, and they know their stuff... But nobody thought about checking the way the wires were rooted in the actual plug, Well you wouldn't normally think, oh I know it must be somebody who has put a nicely wired plug wiring between the breaker and the ignition in the wrong place... Well I wouldn't and obviously these guy's didn't either.. But it has cost four different grades of solenoids, Three batteries (Incl the original one), Three new cables,
a starter rebuild, and because of the type of Starter casing which bolts inside the primary as well as outside, Gaskets, Primary oil, Labour etc.. ( most of this I could have done myself apart from electrics due to a confidence issue..) So loads of money later... The thing that is good about this Run on mod though, Is it got me to look at the wiring and to join this site, and between the two has finally sorted the problem out..
So thank you Sjc69, I don't know where you managed to get that wiring diagram from and to you softail898 for confirming this.. If I can ever help you guy's or indeed everyone else that answered my Query. Thanks again guy's! :cool:
 
I knew of a lot of HD's especially older Pan's & Shovels that had had isolator switches retro fitted to prevent the run on when Solenoids had their contacts stuck, I eventually had the same problem on my '87 Evo so I bought a Durite 0-605-20 Iso keyed switch so you can make the bike a bit more theft proof and safer, as some bikes have to have the seat removed to get at the battery, and can catch on fire before this is done...
 
An excellent thread with top knowledge from Steve. Well worth saving this info.

Mr McQ, don't forget that your kicker on that nice and rare bike can save you on occasion when the electric leg is reluctant or dysfunctional.

The late-style relay is a great upgrade for Shovels and early Evos, because they are cheaply and widely available and take up about 60 per cent less room too.

As an aside, on occasion in the past I have found that TWO thrust washers on the starter shaft have cured a lazy electric start issue, and I could never figure out why that was, but it was a tip I read somewhere once. What is the actual purpose of that thrust washer? Sorry if that's a stupid question, but I don't ask, I don't learn.
 
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