Hitchcocks Forum

A friend ownes a Royal Enfield 500 Electra X, and brought it to me for the repair of a broken exhaust

Besides that, the owner told me there were also some electrical problems. I thought that the replacement of the tappet would be the biggest challenge, yet the electrical issue seem to give me more headaches then expected. I can't get my head around why things happen the way they happen....

First of all, the bike runs and the battery is charging. The headlights and indicators are working, yet already clear is that the rear section has a bit of problem with the earth connection. Disconnecting the whole tail section has the result that the front reacts very normal to any lightswitch that you move.

Up untill the moment when you press the horn. The engine dies immidiately, as if you press the kill-switch. And restarting the engine is impossible, since there is no spark.

yet after about an hour, the spark magically returns, and the engine is easily kicked back to life.

The minute you press the horn, exactly the same happens again. Which also applies for the starter button, perfectly realising that i normally shouldn't press that with a running engine.

Its like the condensator shorts and overheats in that split second you touch any of the two buttons. Is that even possible? Is there anybody that can give me directions to were as this problem may come from?

Thanks

Jeroen
Swakopmund, Namibia

Looks like there is a short on the rear light (pretty common) Could also be a short on the horn wiring. This could be dropping the voltage on the battery to such a level that the ignition won't work. Electra's are fussy about voltage. I suppose the battery could "recover" enough in an hour so there's enough to start the engine again.

You have a wiring fault but the actual cause nigh impossible to diagnose online. The various connectors between wires, and to fuses and bulbs and relays are quite poor - pulling them off and putting them back on clears oxide off. Take a good look at the starter relay, and do check the fuses. And then I'm afraid you will have to trace the wiring back from the horn push to the horn and to its fuse and power supply, same again with the starter button. I fear you have a short somewhere. It is probably something simple and cheap to fix but you have to find it first.

Check the horn resistance for dead-short. Like if it got filled with water.



But that doesn't explain why the starter button would kill the engine, unless that is shorting out too (but then the starter motor wouldn't work at all). Tricky things wiring. I suspect you are looking for one common fault on both systems - they may run off a common fuse.

Thanks PeteF and Jefrs.

Yet it becomes more complicated: disconnecting both the horn and the switch wires to the starter only seems to solve the button-pushing problem. I actually did find some damaged wires already and temporary repaired them by insulating them properly.
After i had the bike idling for a couple of minutes, it died the same way, yet this time without pushing any buttons. That means it could be that the coil is faulty?! Yet i do not understand the relation between the horn and the coil..... ?!?!?!

Jeroen

As jefrs says, you are perhaps hoping for too much if you think this can be diagnosed online.



Electrical circuits are simple things, with just a few basic rules. Things only get complicated when there are lots of them connected together. But the basis rules still apply. The only way to approach this is via a logical and systematic analysis of what is happening. Do the high-level stuff first: measure the battery voltage when the engine is running, and then watch what happens when you press the horn button. If it drops right off, that is why the engine stops. Follow the horn circuit, looking for a short circuit.



Make sure you understand the electrical circuit required to make the engine run. With the engine running, probe the various parts of the ignition system with a multimeter so you are familiar with what it should look like. That should include the 12V and earth feeds to the electronic unit. Find out which one changes when you press the horn button and then report back.



Earth connection faults are particularly puzzling, because they can cause some very odd symptoms. That is why you should always connect your multimeter black lead directly to the negative terminal of the battery. Then, when you find wiring which *should* be at earth potential but isn't, it's a sure sign of an earthing fault.



But honestly, conducting the fault-finding online is going to be almost impossible. Do you have anyone locally who is fairly competent at electrics? It would be much easier for them to fix it, rather than us trying to tell you which connector to probe next.



One last thing (and perhaps going against what I've just said): the one hour recovery time strongly suggests an almost-knackered battery whose voltage drops below that required by the ignition system when you press the horn button, and which takes a long time to recover. Perhaps you could take three measurements of the battery voltage for us: 1/ Before starting the engine; 2/ When the engine is running; 3/ Immediately after you've stopped the engine with the horn button. Measure directly on the battery terminals.

You removed the horn and it 'cured' the horn press problem. This does tell us something, that draining current through the horn kills the ignition - but did you check the horn resistance? Is the horn itself operating correctly.



If the horn itself is good and simply operating it draws too much current from the battery then the ignition may well die. Likewise trying to operate the starter motor when the engine is running, that has a huge current draw.



First thing to do, is check the battery. Check the electrolyte level and charge volts. Use the battery condition meter.




Why on earth are you replacing a tappet for a broken exhaust?



Check that battery!

"yet already clear is that the rear section has a bit of problem with the earth connection". That will be your problem. Make a good job of fixing that and probably all will be solved. Bad earths cause all manner of seemingly unrelated issues.