I think i know the answer.....

New here but not 100% new to VFR's.

Noticed yesterday that on starting the bike the clock went blank and reset itself (including trip counters), my immediate reaction was dead / low battery which led me to thinking it may be a Regulator / Rectifier issue.

I read in the manual that the regulated voltage output should be 14.0-14.8v at 5000rpm, i measured this at the battery terminals and was getting 13.7v at idle speed and 13.2v at 5000rpm. The battery read 12.5 volts witn everything turned off (which seems a little low???).

I've had the bttery connected to the Optimate overnight and i'll re-check it again when i get to work (with a better multi-meter!)..... Do i have R/R probs.... or am i just being paranoid???

The P/O had issues and changed the R/R some time ago (not sure exactly when without digging all the old receipts out!).
Are there any other checks i can do to be sure? What options are open to me should i need to replace? Questions questions :tongue:

 

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More info on the bike.

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If the battery is more than a year old replace it before trying to trouble shoot further.

 

Sounds like it may be time for the ricks motorsport R/R and the VFRness from wiremybike.com I did that almost a year and 7000 miles ago and haven't had a problem since. Oh, a cooling fan from an old desktop computer for the R/R is also in order. I noticed a dramatic drop in R/R temp and the 3 x 3 inch fan only draws .15 amps. I just spiced it into the license plate light.

 

Further news;

Following a night on the Optimate, the battery read 13.1v this morning with everything off, 13.9v at idle and 13.5v at 5000rpm. I'll try an alternator check over the weekend - if the missus give me a few less jobs

 

Good Luck with that!!

 

Battery is weak!

You don't have an RR problem, you have a nearly dead battery.

A battery with no load should read 12.8-12.9 at a minimum, or it is on its way out. At 12.5 volts, yours needs to be replaced. The static voltage means nothing--measure it during cranking and you will see it drop--it has no guts.

The RR seems to be working for you, the 14 volt spec is with a good battery fully charged. The 13.2 you measured is due to high currents trying to charge up your nearly dead battery. High current load will pull down the charging bus voltage coming from the RR.

 

On my previous bike, a 1999 800 like yours, the clock reset was caused by the dying battery, which was getting old but had been killed by the RR. Don't want to be the bearer of bad news but you may be looking at both for replacement. Good luck!

 

Hopefully a little closure now...

I took some of the advice given and bought a new battery, i'd used a 'MotoBatt' battery on a previous bike was most impressed, although they do cost a little more. The new battery for the VFR was £51 and it has appeared to make all the difference.....

14.1v engine running with nothing on, 13.2v engine running with high beam on (13.1v when fan kicked in) and 13.3v with everything switched off.

As it turns out (and as i mentioned in a previous post) the PO had the R/R changed and the upgraded SH689DA unit has been fitted. I gather these R/R's are a lot more reliable than the original SH579A-11 model.
I also gather that these uprated R/R's regulate at 13.8v at higher RPM and that the figures ive quoted above are quite acceptable..... i'd be interested to hear if you think different

 

Also, just to quench my paranoid thirst, i fitted an old 3" PC fan over the R/R and wired it into the tail lights..... belt and braces!!!