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Discussion Starter #1
I have a 1973 Honda CB450 that I thought was finished and road ready but I come to realize I have an electrical issue. The bike was running after countless modifications and adjustments ie new lithium battery, regulator/rectifier, etc. It was running well but i wanted to change the plugs. I followed the manual and replaced the old with new and never turned it over. A couple weeks go by and the battery has since died and the bike wont turn over.
I bought a battery charger and gave the battery a charge but there was no change, the bike still wont turn over.

My question to you all is; Is there anyone or anyplace in North New Jersey that could help me diagnose this issue???
 

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ZAMM Fanatic
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Yeah, No! You can do 90% of the diagnosis yourself. Even if you've never used a voltmeter. It ain't rocket science.

Start with an AA cell or D-cell battery and set up the Voltmeter on DC volts so that you see +1.5V. Now you're ready.

Start by disconnecting the battery and putting a voltmeter on it. I'm not all that familiar with Lithium batteries, but ....should have at least 12V. If not, perhaps take it to Autozone or O"Reilly's for a load test. (12.8 is fully charged for a LiFeP04 battery)

If it sat, flat, for any period of time, it's probably history. A battery is like a swimming pool, as it ages, or if you let it sit flat, the size of the pool schrinks AND the pipes in and out get filled with minerals so it just can't deliver enough water (amps) to spin the starter anymore.

So one way or another, get a good, tested battery INTO your bike. Borrow one, if necessary.

If it still won't crank, (make sure the kill switch is on, kickstand up, in NEUTRAL, etc.) then check all your battery connections, battery to frame and battery to starter (big red wire) connections, just look at them, wiggle them, make sure theyu're not loose, corroded, etc.

If so disassemble, wire brush, clean & tighten 'em. Spray with battery terminal protectant (red)

At the very least you need your headlight, etc. to come on when you turn on the ignition. If they don't, then look for the main fuse and check or replace it.

If you do that with a good battery, and still nothing, then your ignition switch is probably SNAFU.

FWIW, changing the plugs shouldn't have made any difference.

If you DO end up replacing the battery, please do NOT buy another Lithium battery. Get a good old boring lead acid battery because that is what the charging system in your bike was designed to charge. A lithium battery requires different voltages, times, etc. to properly charge.

If after all this you can get the bike to start, then, in neutral, hold the rpm's to 2000 and AGAIN measure the voltage at the battery. If the battery was 12.8 just sitting there, with the alternator charging it it should show at least 13.8 volts. At least a 1.2volt improvement over battery voltage alone with the alternator/stator putting out.

If it isn't, then your alternator/regulator/.... may need some work or replacement. I have no idea how well these 40 year old designs would react to being tasked to charge a LITHIUM battery. Maybe just fine, ya never know!

After you've done all this we'll either never hear from you again or you'll have the info you need to talk to a motorcycle mechanic (or re-post here) for "next steps.

Be sure and turn your meter off.

Cheers!
 

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Just a few details: there is no kickstand or clutch switch, and the neutral switch only turns the light on, but it is a good idea to have it in neutral when attempting to start.

If you want the lights to come on, you have to turn the switch on to test them.

The run/stop switch can be a problem, but should have been a problem before it sat.

The ignition switch could be the problem; its connector is subject to failure, and the wires are soldered to the back, and often break. Also, if you shut the engine off by turning it clockwise from the run position, you left it with the tail lamp on, which will kill a battery in a few hours, unless you have an LED in the lamp, then a few days.

I agree about not using a lithium battery; they require much better regulators than those made 40+ years ago. The charging system, with the lights off, doesn't start to charge until the rpm are over about 1500; lights on, low beam, closer to 1800.

There is only one fuse in this bike, which is in a holder next to the battery. It is a tubular glass type, but not the type that were used in the US; the diameter is just a bit different. Also, the holder oxidizes, especially after 40 years. I replaced mine with a small blade type fuse holder and fuse; the holder has a sealing cap, and is usually available at auto parts stores.

I can email you a pdf copy of the schematic, if that will help.
 

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lost
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Old bikes are fun

And often the host to corrosion. If that battery is able to reach a charge of 12 volts you should be able to get the instrument lights to come on at the very least. Turn signals may come on but not flash. Brake lights and the headlight should also come on. If you've got nothing at all start by looking at fuses and the battery connections themselves. The ground strap is a good one for having a bad connection. Check both ends, not just the battery terminal.

If you find that the battery, fuses, and ground are in good order you probably need to check switches first and then run through the entire wiring harness to see if there is a bad connection. As daunting as this sounds it really isn't that difficult. It is just time consuming. Back to that el cheapo multi meter that wadenelson recommended. It should have an Ohms setting. That will allow you to check switches for function and the harness for open circuits. Zero resistance means you've got a connection. Infinity on the resistance scale indicates an open circuit. That should only occur on switches and diodes under certain conditions (a manual will let you know). You will need a wiring diagram. And if you've got astigmatism a copier that will blow up images is downright handy for keeping you from going all cross eyed trying to follow parallel lines that are too close to each other and too many in number.

A decent manual is handy I prefer Clymer over Haynes for organization and completeness, if you can find one the factory manual is handy too but may be lacking in detail for the novice mechanic. Helm publishes them. These will give you some resistance values for items like the stator, ignition coils etc. It will also let you know what connections should occur at switches so they can be checked for continuity.

What you need to do is visually inspect all connections for green crap living on the metal. A contact cleaner may be all that you need to eliminate it. I have found that you can extract most of the little connectors in multi pin connections by using a paper clip straightened out to depress the tang that is holding it in the housing. If they're really corroded you'll need to replace them or consider soldering the connections instead of replacing them. There are outfits that make OEM style connectors. Bear in mind you'll be cutting wires to shorter lengths and this may pose a problem with reach. In some places that won't be apparent until you turn the handle bars and unplug something.

Ignition switches can be the culprit as mentioned. I had mine develop a problem while flying along next to a line of traffic on a Michigan interstate. Not fun. Turned out to be a bit of slop in the contacts that caused some arcing which led to melting of some of the plastic that held a part that should be floating under spring pressure to make contact. It was barely making contact which contributed to more arcing and eventually it wasn't making contact at all. Right next to a semi at 70mph. Slapping the snot out of the ignition switch offered temporary relief. Shoring things up with solder to keep things from moving around and carving out some of the melted plastic fixed the problem.
 

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Oh, yeah, if you PM me your email address, I can send you a copy of the factory service manual in pdf format, assuming your email server can take a 32M file.
 

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Motorbike Macgyver
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As soon as I read that the battery sat dead, my immediate thought was the battery is toast. For future reference, you cannot let a battery sit dead for very long at all. Before screwing around and wasting time testing everything but the battery, do what Wade said and get a good tested battery in the bike. If you can get your hands on the multimeter, test the dead battery for continuity just to be sure. You can Google how to test for continuity, I did. But a new battery will more than likely solve your problem.
 
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