I have a 1993 Honda F2 and it died yesterday on my way home from work. I came to a light that always takes FOREVER to change and it was in the mid-90's yesterday so I shut the bike off while waiting for the light to cycle. When I tried to turn the key to the on position, there was no electrical power.

Checked:
- No audible noises ie. relays clicking or shorts when cycling the key from off to on.
- The battery has ~ 12.96 V and infinite resistance when the key is in the off position. When the key is turned to on the voltage drops to ~ 0.3 V (bad) and the resistance is around 5 K ohms (seems normal).
- Fuses: The four or five under the right fairing for continuity. They were all good. I then checked a fuse under what looked like the CDI module on the left side of the bike and it was good.
- The SAE pigtail fuse (could have indicated a short) and it was good.
*** I couldn't locate a main fuse and I am unsure of its location.

My friend and I push started the bike and it fired up and ran but just barely. It sounded like it was missing on one cylinder and couldn't rev it above 3000 RPM as it sounded awful. Rather than risk a more expensive fix I grabbed a truck and loaded the bike up and took it home.

I think it is the battery but the strange engine behavior after the roll start has me wondering. Is the stator/generator/alternator powerful enough to run all of the ignition electronics without a battery? If not I would think it is the battery or an errant safety switch.

Any input would be appreciated.

 

Try using a 12v car battery and some jump leads.

(DO NOT have the 12v battery on a car with the engine running.)

If bike starts and runs well with 12v car battery attached it is a DEAD battery issue.

Now to find out what killed the battery.

With the bike engine running at around 2000rpm - check the voltage over the battery terminals - you are looking for around 14v

If the voltage is very low or very high then the reg/rec is toast - replace it.

If reg/rec tests ok you need to check the generator - unplug the loom from the reg/rec and identify the three yellow wires comming from the generator.
With the engine running you should see around 26v AC between any two of the yellow wires.

 

May well pick your "North End" brain very soon with an idle issue my English friend!

 

Thanks for the great guide. And if the rectifier and the generator both check out then we know the battery just went belly-up, right?

 

Yep - but check all three to be sure.

I normally start at the generator.
Generator good - move on to regulator
Regulator good - move on to battery
Check battery

And just to be sure - after replacing any of the parts - do the checks again

 

Sounds great! Thanks again for the input.

 

Things turned out great. Swapped out a new battery and had 12.9V at rest, and 13.6-13.9V across the rev-range. Both the stator and rectifier tested out good. Thanks again for the help, guys.

 

Nice easy fix for a change - cool

 

I'd recommend looking into your regulator/rectifier though and if it is the crappy OEM part to replace it with one that has a heat sink. A lot of people have issues with older CBR's OEM rectifier burning out. Once that burns out it can take out the stator as well (this happened on my fireblade).

Obviously this would cost money, but could save you a stator in the long run. If it already has a heat sink, then you should be fine.