1972 G7S help

[Sacha]

The headlight on my 1972 G7S was burned out when I bought it. It's a sealed beam lamp and the part is no longer available. A guy at NW Vintage Cycle Parts said people are using the headlight from a 1968 YG5T. My original headlight is a 6V/15W and the replacement is a 12V/25W. Is that going to cause problems?

Also, when I checked my battery I found a clear tube in the battery compartment. The tube is not hooked up to anything. It was just threaded through the compartment. I haven't found any mention of it in either the rider's manual or the Clymer manual. Does anyone here know what it might be?

Thanks!

[nayruf]

Hi Sacha

The new headlight is the wrong voltage so if it works it will not shine as bright,

Although physically it will probably fit.

The UK & European bikes use headlight lenses this allows the use of different bulbs,

I would try to find a replacement headlight lens and a 6 volt bulb to suit,

http://www.ebay.co.u...=item336ff5fa57

This is a link to UK ebay an example of this type of lamp,

A fellow US member (flyday 58 or something like that) was looking to do the same thing.

Early Bikes don’t seem to have handed light beam spread so a UK lens should be ok and will not blind oncoming traffic, the US to UK import bikes of this age don’t normally need headlamp changes, so it should be an ok swap.

The clear tube is probably the battery overflow pipe, does it track down through the bike and onto the road, keeping the acid away from the machine?

Hope this helps a little

AJ

[Sacha]

Hi AJ,

Thank you so much for the info! I suppose I should have done a search to see if anyone had already posted about it (sorry). I will look at those links and get my headlight replaced.

You were right about the clear tube too! I've got it all hooked back up and threaded through the frame and out to the road. Thanks again for taking time to help this newbie.

[Sacha]

Good news! The gentleman from NW Vintage Cycle parts has a 6V bulb to go with the assembly he suggested. woo-hoo! I'm getting a new headlight.

[nayruf]

Hi Sacha

It’s good that you can get a bulb headlight set up; replacing a bulb will be easier and cheaper,

The only question left to ask is, what was the reason for the original lamp to blow?

Was it because of age and natural wear & tear or was it because of an electrical gremlin?

I ask this because on my DT which I believe has a similar electrical set up, the head lamp is powered from the magneto not the battery, this means that when the engine is at higher revs it can produce higher voltage. Controlling this is a voltage regulator,

My bike blew its replacement bulb and the regulator looked to be allowing higher than needed volts, with the regulator replaced and a new rectifier fitted just for good measure the bike has not blown a bulb since or ‘cooked’ the battery,

Neither of the parts cost much and they are easy to fit so the fault was easy to overcome.

This is the regulator I used,

http://www.ebay.co.u...=item53db8dea14

This is the rectifier, it is polarity sensitive so the + and - connections need to be the right way round,

http://www.ebay.co.u...=item3f0d70567d

I am not trying to throw a dampener on things, I am just trying to giving you a ‘heads up ’on what could be a further fault,

AJ

[Sacha]

You're absolutely right though. I've been wondering why the lamp was out myself. I thought I'd see how the new bulb does, and then go from there. But after reading your post I think I will look into the electrical system too! You are so awesome for giving me a heads-up. I really appreciate it.

[Sacha]

Okay, so I got the new headlight assembly, but I can't find the voltage regulator. My Clymer manual tells me how to test it, but not where to find it. Is this something I should leave to a professional? My husband has a Fluke meter and I'm sure we could measure the output voltage, but I don't want to start tearing things apart without a clue. Any suggestions are greatly appreciated (as always).

[Airhead]

so it does have one then sacha?...because it seems lots of old yam tiddlers dont!

problem is its a rare bike and theres only you has one lol...so how are we to know

[nayruf]

Hi Sacha.

I assume ‘possibly incorrectly’ that the bike would have a voltage regulator, but AH could very well be right, I would think if a regulator is supposed to be fitted the Clymer manual wiring line diagram would show a schematic symbol for it, My DT/CT manual does not show a voltage regulator for the DT/LT 100 only a rectifier, But you could follow the wires from the magneto through the harness if there was a regulator there then you would find it. With a fluke you should be able to check the output from the magneto,

A 6 volt bulb cost me £3 about $ 4.75 in the UK , so I would just fit the new bulb head lamp set and observe the performance of the bulb with the magneto producing a current.

[Sacha]

so it does have one then sacha?...because it seems lots of old yam tiddlers dont!

problem is its a rare bike and theres only you has one lol...so how are we to know

Well... I'm not sure. That is the trouble.

Hi Sacha.

I assume ‘possibly incorrectly’ that the bike would have a voltage regulator, but AH could very well be right, I would think if a regulator is supposed to be fitted the Clymer manual wiring line diagram would show a schematic symbol for it, My DT/CT manual does not show a voltage regulator for the DT/LT 100 only a rectifier, But you could follow the wires from the magneto through the harness if there was a regulator there then you would find it. With a fluke you should be able to check the output from the magneto,

A 6 volt bulb cost me £3 about $ 4.75 in the UK , so I would just fit the new bulb head lamp set and observe the performance of the bulb with the magneto producing a current.

The Clymer manual has schematics for earlier and later type systems (some show a voltage regulator and others don't). I think I'll do as AJ suggested and follow the wiring to see if there is one. I did get the new headlight assembly installed and when I tested to make sure it worked, I noticed the light seems to flicker quite a bit with any change in idle. Do you think this is a voltage regulation issue or grounding issue? Maybe my best bet is to take it in (I know just enough to make a mess I'm sure).

Thanks for all of your help though!!

[nayruf]

Hi Sacha

Flickering lights whilst the bike is at idle is something my DT does, my DT’s lights also shine brighter and the indicator lamps flash more quickly with any increase in revs. So your bike might not have a problem. With the Fluke connected whilst the bike is running with an increase in revs the output shown on the meter should rise, a regulator should control this to prevent excess, if your bike does not produce enough current to stress the electrics then a regulator might not be needed. However an old friend bike back in the 70’s was blowing his 6 volt head light quite often, so he put a 12 volt stop and tail light bulb in the back light, This 12 volt bulb used up the extra current and his bike ran for years like that but its tail did shine a bit less, it even passed its MOT annual test like that too. But if you feel adventurous and the voltage regulator that is shown on the later wiring diagrams is an easy retro fit you could add a regulator to your bike just for good measure, my bikes regulator has only 1 wire and the body connects to ground, the single wire is connected on an output lead from the magneto it looks to allow excess current back to earth but I assume it really acts a bit like a capacitor, (no doubt others will correct me). I cannot think of any reason why a set up like this could not be used if needed.

AJ

[Sacha]

You all are amazing! Thank you so much. I am scrambling to complete a project for this semester and get my thesis finished ASAP, but then I am going to get on this. I will keep you posted on my progress.

[Airhead]

..........., my bikes regulator has only 1 wire and the body connects to ground, the single wire is connected on an output lead from the magneto it looks to allow excess current back to earth but I assume it really acts a bit like a capacitor, (no doubt others will correct me). I cannot think of any reason why a set up like this could not be used if needed.

AJ

Yes assuming the little G7 has an AC powered headlight

[Cynic]

Even money say's all that little bike has for a regulator is a big assed resistor somewhere near or on the front of the frame in the airflow.

Its all a 72 dt (Well CT's ) had anyhow, HTH.

[Sacha]

Alright! One project finished... still have work to do on my thesis, but I'm getting back to my bike this weekend. It's necessary for my mental health I checked out my battery tonight and it's not in good shape. I couldn't get the tube from the battery tester into any of the holes to check the specific gravity, but on closer inspection it looks like there are actually old spider nests inside it! How is that even possible?! I'm thinking they must have gotten in through the overflow hole because that tube was disconnected. I'm surprised it works at all. Needless to say the next item on my agenda is to get a new battery.

As far as the wiring goes... I did burn out the headlamp bulb (almost immediately) and the indicator lights fluctuate from zero visibility to bright enough to actually see. The turn signals seem pretty dim too (from what others have said). A lot of the wiring is tucked into the frame, but I haven't found a voltage regulator. I've published a pic of the wiring diagram from the rider's manual. Sorry the top is blurry... had a hard time getting a good shot.

I do see a rectifier and am wondering if will be worth it to replace it. We haven't been able to find Mike's Fluke meter either (we cannot remember the last time we used it) so I'll have to see if I can pick up a cheapo one at Harbor Freight or something. Mike currently has his learning permit so he can't ride at night (yet) but I'd like to have my bike ready to ride at night by the time he gets his motorcycle endorsement.

Just thought I'd keep you posted... so you all don't think your advice is all for naught!

[nayruf]

Hi Sacha

Your thesis graphs remind me of hover performance calculations for Harrier aircraft, Your post makes me wonder that if your battery is unserviceable it might be adding to the bulb blowing problem, I would confirm that the battery is ok and that it is charging correctly, I used a syringe to draw up the electrolite and transferred it to my Hydrometer to get the SG measure, if your Rectifier is not turning the A/C to D/C then iI think this could be what is killing your battery, When my bike had this kind of problem I was a bit impatient and I 'nuked' the problem from orbit by changing the 3 components, one of which was the silicon rectifier,

[Airhead]

Change the battery, i'd put money on it that it's no good from your description of it.

Buying or finding the meter would be a good move also, then when the new battery is fitted you can check it's charging by measuring the voltage increase with engine running.

[Sacha]

You two are well awesome! I so appreciate your expertise. A syringe! Brilliant. The only thing that came to my mind was a turkey baster - uh, also not gonna fit. I have a new battery on order... and am also thinking that has a lot to do with my lighting problems. I went ahead and ordered the rectifier while I was at it too. I only found one, and the website stated that it was the "last one". I'll let you know what happens after I get the new battery.

[hover performance calculations for Harrier aircraft - WOW! If only I knew something about that - then maybe I'd make the big bucks. (LOL)]

[btw - here's a pic of the battery (best i could do). the middle cell has what looks like white cobwebs with little black specs - huge ick!]

[nayruf]

Hi Sacha

Looking at the photo the battery does look like it has seen better days, when you get your new battery if it needs to be charged be aware that some switchable 6 to 12 volt chargers as used on most cars have a charge rate that is too high for small 6 volt bike batteries, this can make the battery get very hot and will damage it, if the new battery does not come with instructions on its charge rate I think there is a calculation that you can use to find out, I cannot remember the calculation but if you do an internet search then you should be able to find out more, I think the calculation is based on the precentage of the amp/hr discharge rate but I cannot be sure,

AJ

I know you probably already know this but as well as containing sulfuric acid, lead acid batteries vent off small quantities of hydrogen gas when they are being charged,

[Airhead]

Eeeek that pic...looks like the last view through Titanic's cabin widows

your new battery will no doubt be pre-charged so if you havent got a proper bike charger just stick it on the bike and see how it goes