1998 vfr - Charging Issue

Afternoon all,

Hope everyone is well - looking for a bit of advice to make sure I am on the right track:

1998 Honda VFR Fi

Rode to manchester and back on Thursday (100mile round trip) - bike cut out about 1mile from home - able to get it started again using a jump pack I always carry with me.

Bike is parked in a dry garage at my home, constantly on a trickle charge.

I have tested the battery after charging - reading 12.8v. Starts fine. On idle I have taken a batery reading and it is reading between 13.5 and 14v so initially I ruled out the Reg/Rectifier problem. BUT when i open the throttle above 4k revs voltage is dropping to 8, which means when i am riding the battery is not getting enough juice put back.

My current thought process is:

Replace the Reg/Rec and run the same tests
If the test results are the same, then replace the stator (bike is due an oil change soon but want to diagnose this problem first if i have to drop the oil to replace the stator)

Just wondering if i am on the right thought process with this?

 

You can specifically rule out the alternator with a simple test if you have access to a multimeter. When running/revving you should see something like 50V AC across all combinations of the three yellow wires from the alternator. Also no continuity between any yellow and earth.

From your description it certainly sounds like the RR is failing, possibly one phase diode is dying when it gets loaded.

There's a decent fault finding chart at Electrosport.com.

https://www.electrosport.com/pages/technical-resources

 

Hi Terry,

Thanks for your reply.

Ive stripped the bike down this morning to check the R/R - the 4 - pin connection on the reg rec was fine but the 3 pin into the stator was melted together - i managed to get it part in the end but i thing that has been the cause of the issue.

I will need to replace the connection block at the stator (3 pin) that goes into the reg/rec

Does anyone know if i can buy a replacement connection block, or am i better to just replace the stator and reg/rec at the same time

 

If the alternator and RR are functionally fine, then just cut out the burned section and connector and solder in some new wires with heat-shrink to finish. That is a common failure on the 5G, water gets in and causes corrosion, corrsoion increases resistance, resistance causes heat...and you know the rest.

 

Perfect thanks for your quick reply mate.

I have attached a picture of the connectors; so before I try anything else next thought is to do as you said above (just want to make sure I get this bit right)

Cut off both connectors
Install new wiring and heat shrink together
Run my tests again

Just two quick questions (sorry mate just want to double check)

Does it matter what wires I connect together? I know I will be joining 3 wires but is there any particular order they need to go in?
Is there any particular grade of wire I should get for the pieces I am adding in? I have plenty of solder/shrink wrap etx. so thats not an issue, just want to make sure i use the right wire.

Thanks again Terry

 

It does not matter which yellow wires you join as they are all AC. Get a wire size at least the same as the originals (bigger is better but the originals will always be the limiting factor).

 

If you really want a permanent and weatherproof join then best use Marine heat shrink - it has a glue layer inside which makes the repair completely waterproof.

 

Just wanted to update everyone on this...........

Only had chance to really get into the bike today; I have connected the reg/rec directly into the stator as suggested and have run my tests again. The V is staying above 13 all through the revs and on idle so hopefully this has sorted the problem out.

Leaving the givi rack off for now (for ease of access) until I get the chance to take her on a bit of a run to check everything ok

Thanks to everyone for your help with this (especially @terry)