Help
Several weeks ago I bought a used 97 VFR750 as my first bike ever. It ran fine and I rode it over the first weekend without incident. The next week I realized that the chain was a bit old and rusted so i went again and had a local shop replace both chain and sprockets just in case. Later that same day, after driving about 30 minutes to a friend I parked and realized that the bike was running pretty hot. Attributing the problems to intense heat of the day (around 98 F) I parked the bike and went inside. When I came out a few hours later i realized the clock had reset and the bike wouldn't start. The best I got was an ominous click. A friendly neighbor showed me how to pop start a bike (very useful trick) and I rode home. On the way I noticed several problems. First the lights seemed to be dimming over the course of the half hour ride home. Second, at the stoplights along the way, the bike seemed to be idling really really low and would only want to stay about 1500rpm with a little throttle. Also, at the lights I noticed that the area under my seat (right by the battery) was incredibly hot. Finally, the spedometer eventually died and sat at 0 regardless of my speed or RPM of the engine.
The next morning I called the garage I had had the bike at asking what they had done and what the cause could be. Told it was a dead battery I immidiately attributed it to their carelessness and picked up a new one so I could ride over the weekend. A week later, on another incredibly hot day the bike died again and I had to pop start it to get home. I picked up a battery tender and began exploring this site to try to figure out what had truly gone wrong. I discovered that several people had experienced a few of my problems, but not all at once. In order to solve the problem I ordered a new Regulator/Rectifier, and in order to prevent it from happening again, the VFRness from Wire My Bike.
After testing and much thought it seems that my R/R seems to have completely failed due to the intense heat of the day in combination with Honda's notoriously poor wiring system. It seems that insufficient grounding of the charging system leads to major problems with the R/R. The battery had been overcharging at what could only be incredibly high voltages. The heat even seems to have melted my Starter Relay, located right in front of the battery compartment.
With the new VFRness and R/R, the charging voltage is no higher than 15v and the bike seems to be running great. So for all of you wondering exactly why your battery is so hot, as well as electrical and bike failures, grab a multimeter and check the charging voltage at idle and 5000rpm. It should no higher than 15v, and no lower than 13.5v.
Other than this electrical problem, my VFR seems to be running great and is very reliable. If you have any questions and can't seem to find an answer out there (remember, google is your best friend on this, its such a common problem) feel free to ask.
Hope this helps.
This post has been edited by ale700: 02 July 2009 - 05:28 PM
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