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Old 09-01-2009, 01:31 PM   #1
mitchberry
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Default converting old suzuki t125 from 6v to 12v

is it possible to convert a bike from 6v to 12v?

My reasoning for this is that the headlights on this bike (if it were running) are very very dim, and i'd like to put new model fog lights on the bike so i could actually SEE while driving down the road.

In order to do that, i'm pretty sure i'd need 12 volts.

Granted i know that the engine is only designed to charge a 6v battery.. not 12.. it has a magneto, not an alternator (per say) so, how would i go about doing this? or is it possible at all?
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Old 09-01-2009, 04:48 PM   #2
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As far as I know, you would just swap out the RR, the battery, all the bulbs and anything like instrumentation or horns that were 6V. I dont think you'd have to rewind the magneto because they're capable of kicking out 30V or so.
The starter motor would probably really rip on 12V, so Im not sure what effect that would have.

Take all this with a grain of salt, because Ive never attempted that before...so use at your own risk.
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Old 09-01-2009, 05:28 PM   #3
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out of curiosity, what is an RR? instruments would be difficult unless i retrofitted newer model instruments to the bike, but then i have to worry about gearing and what not.

on the other hand, the instruments are all cable driven not computerized. remember we're dealing with a 1969 suzuki. however, i apparently didn't specify that in this post. My fault.

also, there is no starter motor, it's purely kick start, so no problem there.

There are apparently lights in the instruments though, and i guess those would need to be replaced with 12v bulbs if i could figure out how to crack them open to do so.
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Old 10-06-2009, 09:34 PM   #4
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You can certainly upgrade to a 12V system. RR is the rectifier/regulator but on the older machines they used two components, either a selenium or silicon rectifer, and a zener diode for a voltage regulator (today the two are combined in a solid state unit). The silicon rectifer that you have in use has a zener diode combined with it rather than as a separate unit. It's rated for 6 volts so you'll have to swap it with a 12 volt unit. But it's only "half-wave" rectification unlike the full wave rectification on newer 12V bikes - the difference is that you only get half of the ac power from the lighting coil rectified (single phase) rather than the full wave where the rectifer is able to "capture" both positive and negative sides of the sine wave (3-phase). This means that there is less power available to charge the battery. You will also have to change the headlight, tailight, turn signal bulbs, horn, battery, instrument bulbs, and turn signal relay to 12V units as well. The switches (ignition, brake light, turn signal, etc. should not have to be changed - they should be able to handle the higher voltage (as well as your wiring harness). Changing the instrument bulbs should be quite easy for you. The bulbs sockets are mounted in rubber "plugs" and are pressed into the underside of the instruments. Simply pop them out, exchange the bulbs, and press them back in place. The original 6v bulbs were rated as follows: Tach lamp = 3W, Hi Beam indicator = 1.5W
Neutral indicator = 3W, Turn signal ind. lamp = 1.5W, Speedo lamp = 3W, All turn signal lamps = 8W (each), the headlight was a 6v 25/25W and the tailight/stoplight bulb was a 6v 3/21CP
Hope that helps a little bit.
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Old 10-06-2009, 11:16 PM   #5
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You may also have to replace the ignition coils.
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Old 10-06-2009, 11:21 PM   #6
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That was very insightful thank you.

I didn't know some of the technical things you mentioned, but as for what i'd need to change out, i had figured that out in the last few months and decided not to do the swap. Instead, i just did my best to find 6v bulbs and try to keep it to what it's supposed to be.

i did have 12v bulbs in the gauges though, and that alone was enough to draw too much power for the engine to run at anything less than 3,000 rpm when it was in "night mode."

I pulled all of the bulbs out of the clusters and replaced the neutral indicator light, and the two gauge bulbs with blue LED's, which draw far less voltage. once i did that and replaced the blinker actuator and the rectifier it seemed to run a lot more smoothly at the lower RPM's in "night mode" ..

it runs flawlessly in day mode with the exception of not being able to start -every- time i want it to (which found me stranded a mile from home pushing the bike back (twice) this week)

-------------

aside from that though, i have found that if one WAS to want to convert from 6v to 12v they sell coils on jc whitneys site... rectifiers can be taken off of just about any 12v bike and retrofitted, and same with just about everything else... and bulbs are very easy to find. it's not a big deal to do..
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Old 10-07-2009, 12:34 AM   #7
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You don't have to replace the ignition coils if you ever do decide to convert to 12V - that is because the power for the ignition system (energy-transfer type ignition system) is supplied by a primary coil that sit's opposite of the lighting coil, behind the flywheel, and the ignition circuit is independent of the lighting/charging system.
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Old 10-07-2009, 03:32 AM   #8
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i see what you're saying..

Basically, the alternator should power the coils so it doesn't matter what the battery does.

I get it..

there is one thing though, In my bike, i have an alternator rather than a magneto, so it actually needs the battery in order for the bike to start, so that leads me to another issue. at 12v i may be putting too much power to the alternator and condensers at that point.

But i think with a magneto system you wouldn't have to change the coils for the reasons you mentioned. the battery is only for running the lights, not the motor itself. therefore you don't need a battery at all for the bike to run.

Believe me. i REALLY wish i didn't need the battery for my bike to run.

anyway, am i right by assuming this?
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Old 10-07-2009, 08:50 AM   #9
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You should not need the battery to run the engine. The ignition system incorporates a separate primary coil from the lighting coil. The lighting coil is the source of power that goes to the rectifier and charges the battery. You do not have a magneto (in the true sense of the word) you have what is known as a "energy transfer ignition" which is sort of like a magneto, but uses the primary coil in which electrical current is induced - that electrical current is then "transferred" to the ignition coils (I didn't forget the points and condenser - just didn't want to create confusion). The lighting coil which is separate is your "alternator." This is how most of those models were produced. There were some manufactured with true alternators which employed what is called a "battery-coil" ignition system. In this case, you most certainly need the battery to provide a spark to the engine. This is less common on your bike but became more common place on later units. If your bike does indeed have a battery-coil ignition system, you can still convert to 12V with the components I outlined above. You may have to renew the ignition coils in such a case, but some of them will handle the 12V system. That being said; if you do convert and have a battery-coil ignition rather than the more common energy-transfer ignition system, try it with the existing ignition coils and if they work, you just saved a few bucks. If they crap out and you have to replace them, you were planning to anyway. On condensers: They should handle the increase in voltage. If you indeed have an alternator - you won't be putting power to the alternator. Even with the later used battery-coil ignition systems that used "alternators," the current is induced by permanent magnets in the flywheel - there are no other coils that are fed from the battery. Therefore your alternator only puts power out (to the rectifier). So regardless of which system you have, you should be good to go without any worries other than finding a 12v battery that has the proper rating (capacity in Amp-Hrs) that will fit in your existing battery holder without some sort of modification.
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Old 12-17-2009, 11:46 PM   #10
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Any part numbers for recommended regulator and rectifier assemblies? If my rectifier only has 1 wire from the magneto, I can assume the "other wire" is ground and use a full wave rectifier, correct?


Thanks!
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Old 12-18-2009, 12:10 AM   #11
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wow, i posted this thread back in September.

Welcome to the forum.

Not sure what you're asking specifically though.

The answer depends upon the year, make, and model of your bike.

if i were you i'd start a new thread about this since my question has long since been answered and i've completed my bike / moved on to another one in that time.
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Old 12-18-2009, 12:13 AM   #12
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Quote:
Originally Posted by mitchberry View Post
wow, i posted this thread back in September.

Welcome to the forum.

Not sure what you're asking specifically though.

The answer depends upon the year, make, and model of your bike.

if i were you i'd start a new thread about this since my question has long since been answered and i've completed my bike / moved on to another one in that time.
Thanks for the suggestion!


I'm going to be quite honest, this post was me trying to get up to my 3 post count so I could start a new thread. I figured posting in related threads would be better then making useless garbage posts!
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Old 12-18-2009, 12:20 AM   #13
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cool... no problem. i just hope this thread doesn't get picked up again. that happens fairly often. something from several months ago gets pushed back to the top then i start getting responses again for something i fixed months ago.

no big deal though. the information is out there for anyone else who may need it as well.
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Old 02-23-2012, 02:42 AM   #14
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hi i am from Pakistan and have 1983 Honda CD200 road-master, problem is that i dont find 6 volt battery anymore , can any one advise me shall i put 12 volt battery instead of 6? or its require to change other things in bike? beleve me i m not a technical person so advise me in simple Lagrange..
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