I would like to add my experience to the great article about checking your charging system. There is a part that says to check the windings of the alternator with a multimeter. If the windings have a dead short, it works. If the windings's coating is deteriorated and not fully broken through, it will not work. Here is what happens.
As a motor (alternator, generator, starter, electric motor) heats up the coating expands. Also, the frequence produced by the windings vibrates the windings (AC voltage). The combination of the vibration and expansion cause the deteriorated wire coating to break threw and then you have bare wire to bare wire touching or very, very close to each other. That is the condition.
A multimeter runs off a 1.5 volt battery. The 1.5 volt battery will not generate enough voltage to "jump" the bare wire distance (its "Potential" is too little). It will just test the complete windings length and gives you a resistance in ohms. Coiled wire creates resistance through length (eddy currents). So, a winding that produces 3 ohms of resistance (spark plug coils) have an engineered amount of windings to create that distance which produces the desired resistance in ohms. Now, jump the winding half way and you get half the resistance or 1.5 ohms. Ohm's Law says that Current = voltage/resistance. If you lower the resistance and keep the voltage the same, the current will increase. Current (flow of culomes) creates heat. Heat is what causes burnt wiring, coils, CDI units, etc.
By checking the alternator with a multimeter, the true running condition of the alternator's coiled windings (a Y configuration in our CBR alternators) can not be detected. Once the alternator frequency gets going and the heat builds and the voltage being 60 volts or so AC (AC voltage is measured by the frequency of its peak voltages positive and negative values) the voltage "jumps" to the short wiring condition. Presto, things burn... Amperage increases. My point?
You must use a Meg Ohm meter to check the winding conditions. Meg ohm meters generate high voltage, low current and will "jump" any wire to wire gap where the wire coating has deteriorated. What causes the wire coating to deteriorate? Heat with vibrating frequency.
Hope this helps.
The caveat of using a Meg Ohm meter? If your coating is close to being bad, the Meg Ohm meter may just finish the job. High voltage may "break" the little coating left off the wire and create a bare wire condition. So start with the lowest voltage on your Meggar and work up from there. Using more than 250 volts on an alternator that only produces 60 volts AC may be all you need to check the conditions. If 250 volts breaks the coating off, it might have been a good thing rather than ending up in the Nevada desert wondering when the next Ghost Rider will come by and give you a ride home!

 

Will the alternator on an F4i physically fit and F4? Remember Ohms Law also states that Power = Voltage x current (P=IE) where P= Watts, I = current and E = Voltage. So, if you need 100 watts (power), then the current produced by the alternator must increase since the voltage is a constant with a 12 volt system. To increase current, you would need to have more windings in your alternator windings. The F4i must have more windings in it than the F4. Is there a lower current consuming fan motor available for your radiator fan (look at the motor wattage as an indicator)? You might be able to attack your situation from your F4's consumption standpoint. Rear running lights changed to LEDs would help (LEDs use less amps).
The difference between the F4 and F4i in alternator output is 100 watts and that equals only 8.34 amps (100 watts = 12 volts x 8.34 amps). A lower amperage rear light that puts out the same elumination might get you some of the amps you need to run your radiator fan. I don't know if your laws require a headlight to be on all the time, but a 55 watt (low beam) headlight being off (during the day of course) would give you (55 watts = 12 volts x 4.6 amps) 4.6 amps towards your 8.34 amps you need to make up the difference between the F4 and F4i alternator output.
So, turn off your headlight (during the day if possible) and change your taillight to a LED and you just might make it...
If the alternator from a F4i will fit, you can use it, but you might have to go with a F4i rectifier also (Vb on the diodes in the bridge rectifier - internal to your rectifier -will be the same, but I do not know that the current passing through the diodes would allow the diodes to hold up in your F4's rectifier).
Hope this helps.
P.S. Kerchef's therom states that the total current draw is equal to the sum of all the individual current draws. Reducing some of the individual current draws will give you less current draw thus helping with the heavy draw from the radiator fan so the battery can still get some juice!!!!!

 

Shadow, Technically, I try to avoid the stickies, they lead to slickies in the nickies.... By the way, you are welcome....
Sometimes after painting the living room and drinking JD while listening to Neil Young's Decade album, I can remember things, but then again sometimes I can't.... So, like the famous artist (just call me Leonardo De Stickie), I say fr*k it, and put the paint brush where it belongs - on the neighbor's roof!!!