F4i - Main Forum Main F4i discussion board

Strange random-occurring charging issue

Old 05-28-2018, 10:41 AM
Junior Member
Thread Starter
Join Date: May 2018
Posts: 2
Default Strange random-occurring charging issue

Hello, I'm new here nice to find a place with people that have the same bike.
My F4i 2002(F Sport) always had some electrical problems from the previous owner. At one point I changed the Regulator/Rectifier (with a cheap version though) and everything seemed to start working fine.

Now after 3 months, I've noticed that sometimes the lights are dimmed and it starts with difficulty so I bought and installed a display unit for checking the voltage on the battery. Based on observing the voltage during riding:

I start the bike, it starts charging until 13.5-13.8 even more if I rev it . I start riding and everything still works fine, every time I rev it I can see a hike in voltage comparing to idle. Fan goes in or I switch the high beam, the voltage takes a dip, but after switching them off it returns to 13.8-14 V.

Now totally randomly (from a lot of observations) the voltage suddenly starts dropping and it levels at (what I think) is the battery's independent voltage (12.3-12.8) and there's absolutely no increase in voltage if I rev it. Now the strange thing is if at any time during this issue when it's not charging anymore I restart the engine, the bike will start charging again to 13.5-14 V. I've tested with low rpm riding, high rpm riding, there isn't any difference. Sometimes it happens after 30 seconds after I start the bike, sometimes after 20-30 minutes.

Anyone has any ideas ? I have already followed the Electrosport troubleshooting guide, but it s almost impossible to diagnose it because when it's idle in the parking it ALWAYS charges correctly.

Any ideas ? Thanks a lot !
Old 05-28-2018, 10:51 AM
74demon's Avatar
Administrator and MVN, March 2012/Oct 2013 ROTM
Join Date: Sep 2011
Location: socal 949/951
Posts: 7,684

Have you physically looked at the r/r and the connections yet?
Old 05-28-2018, 01:38 PM
Junior Member
Thread Starter
Join Date: May 2018
Posts: 2

I've looked again right now, all connections and wires look good. The Reg/rectifier is on the aluminium plate and on the frame so it should dissipate heat well enough. But as I said in my first post, sometimes it charges well at any RPM even after 20 mins of riding, so it shouldn't be a problem of heat for the R/R i think. I have yet to look into the Stator though, that is my next stop.
Old 06-10-2018, 05:19 AM
Join Date: May 2018
Location: KC Missouri
Posts: 36

If you have a multimeter, check the resistance between the 3 yellow wires on the stator (check it evry which way) you should show between 0.1 - 1.0 ohms every which way, if so, ur stator is good.

Your positive the connection is good? The main one that goes bad is the yellow plug from the stator to the rectifier. Make sure your battery terminals are tight, and the main ground wire that connects directly from the battery to the mounting bolt for the starter is tight.

The bike wont really charge at idle, it doesn't really start to charge until you are up in the rpm, especially if the fan and/or highbeam are on. It will most likely lose power slowly with the highbeam and/or fan on at idle. Does it drop below say 13.5v if yourrpms are over 2500-3k?
They rate the stator to output full power at 5,000rpm! But it still charges fairly well at 2500+.
Related Topics
Thread Starter
Last Post
F2 Tech
01-27-2018 02:05 PM
General Tech
08-04-2015 01:57 AM
CBR 1000F "Hurricane"
01-30-2015 08:39 AM
General Tech
04-11-2011 11:35 AM
CBR 600F3
06-14-2010 07:41 PM

Thread Tools
Search this Thread
Quick Reply: Strange random-occurring charging issue

Featured Sponsors
Vendor Directory

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.