Boxerworks.com

Hi, Some of you may remember me as Epochmaker from the UK. I have been absent for a long time, I recognise some members here from way back then.

I have an R75/5 which I bought in boxes as a 'project' which was unfinished. Many hours, ££££ and much help from your good selves got the old bike on the road.

I have kept the bike, it has been laid up for years, 4 or 5? maybe more... My wife left me and I moved to a town centre flat with no room for a bike. Now I have a little cottage by the sea where I will be able to keep it handy and be able to use it regularly I hope. It has been stored in a garage since last it was used, although at present it is outside until I can build a shed for it.

I tried to rejoin the forum a few months ago but it has been revamped so I have had to re-register, I have chosen a better username. I have been working on the cottage since I moved in January only managing a few moments to try to get the bike roadworthy.

I have fitted a new battery, the larger 24 Ah? battery used in the later R bikes. I have an engine mixture adjustment and a starter problem I need help with in due course but right now I have an electrical problem I would appreciate help with...

From time to time I have been starting the engine and running it, taking the bike for a ride around the block just to keep things moving, and because I enjoy have the fun of riding it occasionally.

Yesterday I started the engine, all seemed OK it started easily left it ticking over for a couple of minutes, then set off for a short run around the block maybe 200 yards? As I set off smoke started to come from the engine, acrid black smoke which smelt electrical, if you know what I mean.

I immediately killed the engine, fuel off and raced to my tool box for spanners to remove the earth lead. The smoke stopped when I killed the engine. The ignition warning light, which normally is off when the alternator is charging was ON after I switched off the ignition.

I have not had time to investigate properly but today I removed the front cover. I found the two wires which connect the alternator rotor to the voltage regulator were burnt. Both wires are burnt right through and severed close to the alternator about two inches from the LH terminal looking at the alternator from the front. I have not yet removed the fuel tank and engine top cover so I am unable to say if the burning extends towards the voltage regulator. I am currently away from home so I can't access the bike right now. I found molten globs of copper at the bottom of the front engine cover.

I assume there has been a short circuit to earth, or between the two wires feeding the Rotor. Is this likely to have damaged the Voltage regulator, and is there any test I can carry out to test the voltage regulator for operation?

I will check the continuity of the rotor, there is no sign of burn shellac on the rotor windings or the field windings. The only burning I can see are the wires I have mentioned.

Would appreciate any suggestions or comments so I can get to the bottom of this. I will post images of the burnt parts as soon as I can.

Some of early /5 were fuseless but by 1973 all had fuses

I see no reason for a big battery on a /5

with LED lights in the tail and LED idot lights used with a H4 headlight my bike is well lighted and electrical efficent

with just enough extra juice just handy for a heated something which I never use or own....

a electrical solid state Regulator set to 14.2 is a good thing

I'm afraid Robert cooked his chargeing system, if he had the old electrical regulator I'd make a bet it stuck


Welcome back Robert

Thanks for the welcome guys

I always try to fit the biggest capacity battery I can on anything, does no harm and allows leeway if for some reason I have difficulty starting or if the charge circuit fails, I stand a better chance of getting home or to somewhere safe.

The bike is a 1971 ex French police bike imported to the UK in 1972. Registered as 1972. It has the longer wheelbase, allowing room for the the bigger battery between the rear of the air filter clamshell and the rear mudguard. Also has /6 front forks with single disk. Yes, it is completely fuseless, I may address that this time.

I don't yet know about the regulator, yes it's the original electrical unit, I have wondered about it, but it has functioned fine until now, it may still be OK but I like the idea of an electronic regulator. Are these available or do I have to find one from another bike, any suggestions? (remembering I am UK based)

My initial reaction is the wires have grounded on the alternator mount lug but until I can remove the tank and top cover I won't be able to trace the wires back.

Also if that much current HAS been running through the voltage regulator then if it was OK, I doubt it will be now, those wires have been very hot, dripping copper means a lot of heat.

Robert, you keep talking about the voltage regulator, but you also talked about finding gobs of molten copper under the front engine cover. Your voltage regulator is not under the front engine cover. It is mounted to the frame under the gas tank, probably on the R/H side of the top frame tubes.

The electrical component that is under the front cover is the diode board, which converts the AC current from the alternator to DC current. The only copper that might be associated with the diode board would be the etch itself. I would think the etch to be so thin that you wouldn't get gobs of copper from that.

I'm guessing the copper came from the wires that fried. But it could have also been the alternator rotor or the alternator stator.

When you tear things down the source of the copper will surely be evident.

Your problem appears a bit snarly. No only are you going to have to replace whatever it was that might have melted, but also fix the melted wiring. The good news is that you're asking the right people.


Ken

Thanks for your input Ken, I guess my initial post was long and convoluted.

The globs of copper are from the melted wires, the reason I am mentioning the Voltage regulator is that the wires connect the rotor to the voltage regulator. If that amount of current has loaded those wires I hate to think what the state of the Regulator will be. I am expecting it will need replacement, if only to upgrade to Solid State.

There is no sign of the rotor or field (Stator?) alternator windings having heated. The three wires from the field (Stator?) to the Diode board show no sign of heat nor is there any apparent (Visible) damage to the Diode Board.

I had not expected to be away so long but I should be able to post pix tomorrow and more detail of the track back on the burnt wiring.

Seems to me the more I think about this, the two wires from the regulator to the rotor brushgear must have either shorted or grounded. Grounding would only have burnt one wire because the other has zero potential? That would suggest a breakdown of insulation on both wires and a short between them fed from the regulator. These wires are original so it's not impossible they were cracked. I have been into the starter recently (Another story) so obviously the front cover has been off and the wiring disturbed.

I still wonder why the Generator warning light was on after I switched off the ignition. That would normally indicate a blown diode?

Sorry for the delay.

I have taken the fuel tank off, removed the Voltage Regulator and opened it up. I have inspected the wiring and the only wire which I can find which appears to have been overloaded is the brown wire from the Voltage Regulator to the Rotor brush assembly.

I have checked for continuity between ground and the rotor slip rings, that seems OK, no continuity.

I am a bit concerned that the D- terminal on the Alternator cover is Ground, I had not expected that.

It appears to me that the brown wire is negative (ground) and the blue/black is positive. For the brown wire to have been overloaded it must have come into contact with a substantial positive current. If it was from the blue/black field wire I don't understand why the blue/black wire shows no signs of overload along it's length. It appears thinner than the brown wire.

I can see no signs of overheating inside the voltage regulator. There is continuity between all three terminals of the voltage regulator even when I manually operate the relay.

My next move is to investigate the Solid State Voltage Regulator suggestion. Nobody has told me where these can be obtained, I will got onto Motorworks site and see what they offer. Is this what I need?

http://www.motorworks.co.uk/vlive/Shop/ ... 20ELA44410.

Some pix of the burnt wiring... If I can figure how to post images. OK, how do you post images please?

Robert B wrote:If I can figure how to post images. OK, how do you post images please?

Post your pix to a website, eg photobucket. Then in your thread reply, click on the "Img " above the text box, then copy your picture url from photobucket and paste it between the Img thingees.

Hmm, I just read that and it doesn't sound very intuitive...good luck.

or...

FAQ wrote:Can I post images?
Yes, images can be shown in your posts. If the administrator has allowed attachments, you may be able to upload the image to the board. Otherwise, you must link to an image stored on a publicly accessible web server, e.g. http://www.example.com/my-picture.gif. You cannot link to pictures stored on your own PC (unless it is a publicly accessible server) nor images stored behind authentication mechanisms, e.g. hotmail or yahoo mailboxes, password protected sites, etc. To display the image use the BBCode [img] tag.