Checking the Regulator Check the battery voltage with the engine running and above 3000rpm and you should see 13.5 to 14.5 volts dropping to 12.5 - 13volts when idling. This indicates that your battery is charged and alternator and R/R is working ok. If the battery drops below 12 volts with lights on when idling or engine stopped, then your battery is not charged. Replacement Regulator Most bike regulators will do the job as they use a similar principal to operate. All unused power generated is shorted to ground leaving only what is required to run the bike and charge the battery. It is not uncommon to use one off a different brand bike even.As long as you get the three regulator wires that are the same colour joined up to the three alike coloured wires on the bike from the alternator, the red and black are obvious (+12v and ground respectively) you won't have any problem. Alternator Normally the alternator would put out something like 50-100 volts AC at high revs when it is disconnected from the rectifier/regulator. The alternator is 3 phase (with 3 output wires) and that voltage should be measured equally in all 3 combinations of connecting to those 3 wires. Also check that the windings are not shorted to the earth (metal casing of the engine) using the ohms range with one meter lead on the engine and the other on any of the three alternator wires. Must be unplugged from rectifier/regulator.
Just looking for some confirmation from others on what I've diagnosed. Bike - 1988 FZR250 2KR Symptom - If I ride the bike with headlights on for say 45 - 60 minutes the bike will suddenly cut out due to low battery voltage. Bike has no juice left to crank once dead. Leave bike for a few hours and try again and the battery has recovered enough to start the bike. If the bike is running with headlights off I havent witnessed any issues, (but maybe they take longer to present?). I have replaced the battery and issue persists. What I checked - 1) Checked battery voltage prior to starting bike, 12.15V, OK 2) Checked battery voltage once bike was running at idle, 13 to 14V, OK 3) Kept multimeter leads on battery while increased revs - voltage increased to 16 to 17V, not OK. 4) Disconnected alternator plug just before rectifier - 4a) Checked resistance between each stator coil (3 in total) to ground - no resistance noted (on a cheap multimeter), OK 4b) Checked resistance between each pair of stator coils (3 pairs total) - all approximately 1.5ohms, seems OK but not sure on allowable values 4c) Started up bike with multimeter measuring AC voltage across each pair of stator coils (3 pairs total) and ran through the rev range - all ran from around 50 to 100VAC @ 14,000RPM, OK So at this stage to me it looks like the regulator in the R/R has given up the ghost. What normally happens when an electrical system gets a higher voltage? I'm guessing since mine still all works not a lot other than wrecking the battery prematurely? Also, any pointers on what replacement R/R to look for? (I.e. I guess it needs the same plug and rough dimensions.) Any pointers would be much appreciated.
Bit of a bump to a 7 year old thread ? Yeah sound's like your reg/rect is kaput. Battery might be on it's way out too if it's showing 12.15v with the bike off, should have 12.6v - about 12.9v when it's fully charged I fitted an R6 reg/rect to my FZR250, think there's a pic of it on the first page of my thread, the link in below in my signature Where about's are you located ? I might be able to link you a reg/rect ?
Thanks for the info. Located in Perth, WA - I found a bunch on ebay (e.g. here) that look the same so might give one of them a whirl.
Yeah the 'YHC' reg/rect's are a cheap china copy of the original Shindengen Reg/rect's You will need to modify the wiring to the plug to use that one on your bike. It might last for a while, but i'd rather trust a good used or new genuine reg than a cheap chinese copy
Not sure if this is any better quality than the one you linked, but it's not a YHC reg and it's a direct swap for your original reg http://www.ebay.com.au/itm/Regulato...651943?hash=item4b0b734927:g:F4AAAOSwKOJYGZHQ
The worst thing with the china regulator's is the wait for them, 3 - 4 week's This is a decent Japanese reg/rect, it has a slightly higher output than the original FZR reg/rect's and just need's a simple 6 terminal plug made up to adaPt to you wiring Would cost you under $20 inc the plug (jaycar repco/supercheap) I can draw up a diagram if you're interested http://www.ebay.com.au/itm/VOLTAGE-...221382?hash=item2cab94df06:g:4eYAAOSw3mpXIMkJ
A bubble in the potting on the back of the reg/rect ? Yeah most likely a blown diode. Have you checked the voltage at idle, and at 4000 rpm's ?
Only just noticed it the other day, thought it was due to a replacement flasher relay from jaycar, might test the voltage next week
