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Falcon 87 wiring problem?

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Falcon 87 wiring problem?

Post  devices on Sun Jul 20, 2014 5:34 pm

Hi Chaps,

I've just purchased a Falcon 87, and its a great little ride. I've never owned a classic before, having only ridden modern stuff.

I've only done a couple of journeys on it, and now I've run in to a problem. I rode it to work one day, and when I came to ride home it wouldn't start. I discovered the 20amp fuse that was fitted was burnt out.

I have a wiring diagram, but unfortunately I don't see anything wrong, apart from the battery appears to have a slightly melted corner, and one cell was significantly low, with the little stoppers popped off the top.

I'm of the new generation where I plug my computer into my modern car/bike and it tells me what the problem is, but I'm currently a little stumped - I'm going to get a new battery for it, and see if that helps, but any pointers would be ideal. The bike has a new little square rectifier unit fitted instead of the old flat one, and has all 4 connectors connected.

If it is possible to wire the bike up to run without a battery, that'd be ideal as its only going to be used occasionally.

Any pointers? Sorry for the vague info, I'm still learning about it. Mechanical stuff is fine for me, if it was a carb problem I'd be happily working away, but electrickery has always been my weak point.

Or if anyone knows anyone in Surrey/Hants/Berks area that I could employ to help, that'd be great.

Thanks Smile

devices

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Re: Falcon 87 wiring problem?

Post  banjo boy on Sun Jul 20, 2014 7:34 pm

Hello and welcome to the world of Francis Barnett I to have a model 87 but still in the rebuild stage but my knowledge of electric's is not my strong point ,but I can say that you can not run the bike without a battery.if it had a magneto then you can but these bikes do not .With the fuse blowing my be you have a earthing problem.I am sure some one here will put you right.
banjo boy Cool 
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Re: Falcon 87 wiring problem?

Post  devices on Sun Jul 20, 2014 9:00 pm

Thanks for that, it does at least remove 1 thing I can look at.

I can't find a bad earth, or frayed wire, or bad connection anywhere I've looked so far. Bike was restored last year, and was running perfectly, idling like a sewing machine, I just can't work it out.

devices

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Re: Falcon 87 wiring problem?

Post  Jack Clegg on Sun Jul 20, 2014 9:39 pm

Hi. You really ought to be finding out why your battery melted first. You may just end up frying a new one. Could be an overcharging issue. If the tops have popped off all the cells it was probably gassing like a chimney. One cell caught it worst it seems. Let's hope that's not the case, could just be a duff battery. Did the replacement fuse blow again immediately? TTFN Jack
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Re: Falcon 87 wiring problem?

Post  devices on Mon Jul 21, 2014 12:02 pm

It blows the fuse the moment I hook a battery up.

Overcharging sounds likely, I thought the rectifier was supposed to regulate the AC voltage from the Alternator to a sensible level, or am I missing something?

I've got to work out how to take the headlamp/switches apart so I can look in there to see if anything is amiss.

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Re: Falcon 87 wiring problem?

Post  devices on Tue Jul 22, 2014 6:12 pm

Found a short in the cable from the battery to the ammeter. Ran a new length of cable and it fired right up.

Just got to work out why it shorted out, as some of the insulation was a little melted.

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Re: Falcon 87 wiring problem?

Post  Jack Clegg on Tue Jul 22, 2014 7:46 pm

Could still be overcharging. The battery & part of the loom has got pretty hot. Why, is the big question. There has to be some sort of Zener Diode or a resistance wire in the circuit otherwise it'll get 'ot. The lead from battery to ammeter fits the scenario, it all got very hot.
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Re: Falcon 87 wiring problem?

Post  devices on Wed Jul 23, 2014 12:52 pm

I'm sure it is overcharging - I've noted the resistance wire in the wiring diagram, I'm going to spend a little more time going over it. Makes it significantly easier to diagnose when it has power!

I've also noted no movement at all on the ammeter. I expect that is related.

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Re: Falcon 87 wiring problem?

Post  Jack Clegg on Wed Jul 23, 2014 1:51 pm

No movement plus or minus? Probably cooked the ammeter too. You might be better off fitting a Regulater/Rectifier from Paul Goff. 6 volt type will handle it all.
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Re: Falcon 87 wiring problem?

Post  devices on Wed Jul 23, 2014 4:03 pm

No movement that I've seen.

It has a square modern rectifier, fitted with the re-wire last year. Now I've got it running I can test everything with the engine running, I'm just waiting on a delivery of glass fuses.

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FB Falcon 87 electrics

Post  FB vincent on Wed Jul 23, 2014 9:07 pm

devices wrote:No movement that I've seen.

It has a square modern rectifier, fitted with the re-wire last year. Now I've got it running I can test everything with the engine running, I'm just waiting on a delivery of glass fuses.
 
The AMC engined 199 and 250cc engines used Wipac electrics, a system used by many other manufacturers of the time. In good condition, the system provides a good output for the dc ignition coil and lighting. No fuse was included, and the resistance wire is only cut in when the headlamp is not in circuit. Whether an original Wipac selenium rectifier is in circuit, or a modern replacement, the critical item for the voltage regulation is that the 6 volt battery should be in good condition and the terminals clean. Use the 'Search' function on this forum for discussions on rectifier wiring. You say that the bike was re-wired, have you carefully checked this against the wiring diagram? The headlamp switches cut in the coils progressiveley to (a) power the dc ignition coil, pilot light plus resistance wire, then (b) the headlamp. The 'Emergency' switching cuts in all coils. The FB handbook provides a user testing routine for all components. The ammeter is important in determining what is going on - testing of all circuits should take place without the engine running, but in all conditions a total discharge or charge suggests a problem. Good luck with your project - remember that you are not alone with Wipac, the Prince of Darkness. (But to provide balance to this forum, Villiers magneto systems have their own problems).

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