Hi John, thanks for the reply let me start from the beginning, are you sitting comfortably!
I bought the bike from a chap in Huddersfield, pieboy, I believe, although his name is Mark. Rode the bike home (Bath, Nr Bristol) no problem. Set about cleaning it up the next day, as you do, and tucked it away, no problems. Went back to it the following morning, flat battery. (bike was left idling a long time the previous day, thought id mention this as i know they dont charge much at idle). Checked the charge rate, 13v at 5000rpm, oh sh*te!
Didnt panick, put the battery on the optimate and left it for a week. Had the battery tested,(good tester, good dlr), and it was ok. I have just been down to the garage and started the bike on a fully charged healthy battery and the readings are as follows; at idle charge rate of 13(+or-0.2v) volts. at 500rpm, engine warm, 14.10volts, switched on the headlights and brake lights and at 5000 rpm charging voltage went up to 14.35/40 volts. now i know that honda recommend a charge rate of 14.9-15.5 volts at 5000rpm, and just to check they do actually do that i contacted a mate down on the south coast with exactly the same bike and his charge rate is 14.9 at 5000 rpm, no lights on etc so i know they do do it. the problem i have is knowing what 'bit' to renew. I have been a car mechnic for 25 yrs so i am assuming that the charging system on the B/B is basically the same principal as a car, i.e. if the battery has a loading put on, i.e. lights switched on etc and the charge rate increases then the regulating system is working? that is what mine is doing so am i fairly safe to assume that the reg is ok? I am warming towards your suggestion that the alt/dynamo, (the bit inside the l/h engine cover), is faulty. Now i am faced with 2 options, 1 is to repair the bike and 2 is to just leave the battery on charge permanently as it is only used some weekends. I personally will not be able to sleep properly knowing the bike has a fault (sad, I know!) so repairing is the only real option for me. I know that no-one can give me the ultimate, 'yes, that will cure it' answer but you have a much wider knowledge of these than I do and so would appreciatte any help you could offer. The bike is a 2002 FI uk spec, no alarm, just H.I.S.S. as std.
hope you can point me in the right direction, rgds,Steve.
p.s. do you keep the parts? i.e. alt/dyn/reg, if so, what are the costs?