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ELECTRICAL QUESTION / TW200

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Hellwig

Hellwig

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Recently picked up an old abused tw that was not running and have been making steps towards reversing that. carb rebuild and cleaned, tank derusted, wire harness sorted.

Some one thought it would be a good idea to cut off all the street legal bits, so the harness is there but nothing else except switches and headlight. Fast forward to starting:
With a battery, the engine fires off and runs, but without a battery connected, it will not run. Using the wiring diagram from the manual I gleaned online the culprit proved to be two relays: Ignition circuit cut off, and starting circuit cut off relay. I thought about just buying a battery, but it aggravated me that if the battery were completely dead, the dern thing would not kick start, so I pulled the relays, jumpered the connectors, and BOOM the bike kicks over fine and seems to run with no problems. I insulated the jumpers and the positive battery terminal with electrical tape to prevent shorts.

My question is, will this negatively affect the electrical system or hurt the bike in any way? The headlight did come with the bike, and I have thought about maybe trying to make it work and so would probably have to buy a battery in that case, but in the meantime it seems fine. Does anyone have any idea?

Thanks in advance.
 
Are you confident in dealing with an old school bike?;-) That relay stuff was just some safety bumpers for beginners. As long as the charging system is functioning you are ahead of the game.
 
heck yea im confident, so far just minor issues considering its a 26 year old bike. compression is good, valves adjusted fine. still gotta get some cables and check out the swing arm, rear wheel bearings and brakes, new fork seals, but bike looks like a solid buy so far. since speedo and all is missing along with the title, it is going to live the rest of its days as a fat footed dirt bike.

what exactly do i need to be concerned with the charging circuit -as long as it fires? i am ignorant is why i ask.

thumb-fumbled from my Obama monitored electronic leash
 
the typical small bike charging system needs the battery for the charging system to function correctly. generally the regulator will not regulate without the battery. you will start the bike and the headlight will light up but as the engine is revved the voltage will go up but not cut off and it will blow the bulb due to over voltage.
 
ok, so if running the headlight i need to worry about over voltage to the headlight, but if i do not run a headlight or other electric option, will it harm the bike, with no battery? If so, how can I simply bypass whatever would be harmed to run safely without a battery?

Except for tires and fuel, batteries seem to be one of the costliest expenses on all my equipment, so I am trying to avoid having one in the TW if possible. If it is a real pain, or expense to run without it, I can buy one, but it is a weird size (different from any other bike battery I have) and I was just looking for a way to eliminate it since I dont have to run electrics.
 
wow just looked up the diagram for that bike! they did over complicate it didn't they!

it will run just fine, it uses a CDI ignition system that is not connected to the lighting system in any way other than shared ground (frame) the regulator may work. you will just have to use a multimeter to test the voltage at various RPM's. likely the light will only produce usable light above a set rpm level and be dim below that.

if the voltage rises to high (over 14.5 volts) there are ways to correct it.
 
LOL, Ive got jumpers in place all over that harness. Neutral switch, clutch switch, side stand, ignition relays etc.. I cant help but think, I could cut out and remove most of it for my purpose but I hate to do that to a perfectly good harness. I think it will suffice to just cap and isolate / jumper where necessary. Thanks for sharing your knowledge and excellent advice. I am learning a ton working on these old bikes.
 
The regulator should work regardless if the battery is present. The 14V is to charge the battery, once the battery has reach maximum load the voltage is still there only the system does not draw as many amps. Well let me clarify that, it draws as many amps, the battery just supplies them. There should be 3 wires into the regulator, typical they are yellow, each one of these should have a AC(alternating current) on them being 60 Vs each. This is then combined together through diodes in the regulator to create a 14 V DC (direct current) by using a diode called Zener that puts anything above a preset voltage shunted to ground. The regulator is finned, keep it in the air flow but free from debris. It converts the energy to heat, heat ruins the silicon devices with in the case. You do need a battery, this adsorbs drains on the system better than the regulator can and prevents the regulator from being over whelmed and over heated trying to keep up with amp drain. Say you add some electronic device,Switching head high to low, brake lights. the battery keeps the system stable as the alternator fluctuates during engine speed.

Did that make sense?
 
sure it makes sense to a degree, but will it damage the regulator or other components if no appliance(lights) or battery is present in the system? if it will be dangerous to a component, is there a work around for it? change the regulator or generator? unplug it?

thumb-fumbled from my Obama monitored electronic leash
 
I had a yamaha xt350 that was converted to off road only and it would only regulate with a battery hooked up, remove the battery and it would burn out the headlight bulb.
I agree that the regulator should regulate battery or no battery but in that case it wouldn't.
Minor issue, we did very little riding after dark.
We did do a loop of a enduro course by moon light once and that was a rush.


Sent from my iPhone using Tapatalk - now Free
 
Hellwig said:
sure it makes sense to a degree, but will it damage the regulator or other components if no appliance(lights) or battery is present in the system? if it will be dangerous to a component, is there a work around for it? change the regulator or generator? unplug it?

thumb-fumbled from my Obama monitored electronic leash
Click to expand...

The battery acts like a buffer, that collects the surges that happen when you add RPMs. Higher RPM higher output, higher out put in both voltage and current. These surges are hard on all the electrical devices. Install a small inexpensive battery, $14 at Wally place. You have a CDI ignition, keeping it at an even steady voltage state gives you a better spark. Any thing else is just a bunch of work.
 
A capacitor can work as well. Much smaller and almost no weight..
 
Found on tw200forum.com but I dont know how well it works. "Go find a nice 10,000 microfarad 25 volt capacitor, and replace the battery with it (making sure to connect positive to positive and negative to....negative!)" The original thread is here:
http://tw200forum.com/forums/7722/ShowPost.aspx

I happen to have a 19000uf at 30VDC 40 surge with screw lugs and all. Anyone see a problem with this for no lights etc on the system?
 
Hellwig said:
Found on tw200forum.com but I dont know how well it works. "Go find a nice 10,000 microfarad 25 volt capacitor, and replace the battery with it (making sure to connect positive to positive and negative to....negative!)" The original thread is here:
http://tw200forum.com/forums/7722/ShowPost.aspx

I happen to have a 19000uf at 30VDC 40 surge with screw lugs and all. Anyone see a problem with this for no lights etc on the system?
Click to expand...

caps a cap, looks like you just saved you $14 plus tax.:lol2:
I was thinking about a cap earlier today. To a circuit they act similar. Accept a charge and put power back into the circuit when voltage falls below a certain level.
 
1-what if the regulator won't work without a battery, or does and then fails?
2-at what charging voltage without a battery will the CDI get smoked?
3-how much does it cost to find/replace the ignition system?
4-what was the reason the bike mfgr engineers put a battery in the bike?
5-Is the least costly/headachy solution to buy a $14 battery?
My experience with regulators is with far more fancier systems. However, your bike has some electronic stuff and would probably be very happy with a battery in the bike.
good luck! YMMV
 
Last edited:
wanabeguru said:
1-what if the regulator won't work without a battery, or does and then fails?
2-at what charging voltage without a battery will the CDI get smoked?
3-how much does it cost to find/replace the ignition system?
4-what was the reason the bike mfgr engineers put a battery in the bike?
5-Is the least costly/headachy solution to buy a $14 battery?
My experience with regulators is with far more fancier systems. However, your bike has some electronic stuff and would probably be very happy with a battery in the bike.
good luck! YMMV
Click to expand...

the only connection the CDI system on that bike has with the lighting system is a couple safety interlock relays that have already been defeated.
the CDI gets its power from separate charge coils on the stator.
no regulator required no lights and no battery required.

it does require the stator as the charge coils for the CDI are integrated into the stator assembly.
 
strange thing, i added the cap mentioned above and bike starts and runs fine but voltage at the cap now reads 1. i have not removed it to check without yet. i will post up results after testing by removing cap and checking voltage again. if it still is producing 14v i guess i have a bad cap and may just put in a battery and try reinstalling the headlight for rare night rides. thanks for all the input.

thumb-fumbled from my Obama monitored electronic leash
 
focus frenzy said:
pretty much, it substitutes points for a electronic trigger.

here is a pretty good tutorial and animation of how a CDI ignition works.
http://www.vespamaintenance.com/elec/cdiwork/
Click to expand...

Pretty much what I built from a kit for my '70 440 six pack charger that would always diesel. I originally left plug gap at .032 but burned the electrode completely away. After that I gapped at .060 recommended. JC Whitney had the kits as well as other aftermarket suppliers. Capacitor was huge! Worked like a champ with factory dual points. Still only got 10/gal:trust: but brutal torque
 
Update on the TW project. I was only able to get 1V at the capacitor after installation, so I removed it and now only getting 5-6vAC, so I just removed the cap. isolated the hot battery connector and she is still running and starting just fine. I am not sure if I imagined 14v prior or if I smoked the generator with a bad cap or what, but in any case I do not think that 5-6v is enough to recharge a battery and so will scrap the idea of re-installing the headlight with a new battery for now. From what I have read the 87 TW had a weird electrical system and many issues ave been documented (leading to updates in the following year TWs.

Thanks all for the help. If I get back into this project at a later date, will update on progress but as this bike is my daughters trail bike, it probably will not happen anytime soon.
 
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