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Jul 06

Posts: 7

JEZMAN74 says:

vfr 750 f/l cdi and reg/rec

hi all having some probs with my vfr 750 f/l 1990. on last ride out the bike decided to cook the battery. so after getting it recovered obvious choice and agreed by the aa man was regulator/rectifier had gone. i am rebuilding my honda firestorm and had been told reg/rec would fit the vfr. so switched it over onto vfr found it had popped the ignition fuse so replaced that and fitted a new battery put the key in and she fired straight up. after about 3-4 minutes ticking over and gentle throttle smoke poured out of side panel so hit kill switch but carried on smoking till i turned key off. it had fried the CDI this time. got another CDI but reluctant to fit it in case same happens. any ideas whats caused it to do this most appreciated ! thanks all.


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  • Posted 2 years ago (25 November 2012 23:22)

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Aug 09

Posts: 2693

MarcusMarsh says:

VFR Charging systems

The problems with the VFR systems is that the regulator/rectifier doesn't always die instantly and on the way out it will take either the battery or alternator with it.  You then have a situation where, if any one of those components is dying it can take out the other two.  The only way to be sure the system is OK is to check everything and make sure that the reg/rectifier, alternator and battery are all OK.  These are all easily checked with a multimeter. 

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Mar 09

Posts: 8819

jaffa90 says:


I doubt the alternator but you can check the resistance and  a/c output as said with a multimeter,reg/rectifier i would not just put any on. You could try a new battery after being off charge for a hour reading 12.8v 12.9v start up with alternator disconnected from the r/r and then checking your alternator output,3 readings a/c all similar and if ok stop engine reconnect 3 wires, start up and check battery voltage in d/c if the voltage goes above 14.5 volt d/c in any revs switch off.  Your r/r is u/s.

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Jan 08

Posts: 7171

kcmc says:

Honda VFR 750 FL 1990


Doesn't sound good,think this problem may well be in the wiring harness,probably a live wire has melted and is shorting out into another wire that can make it to the CDI,the CDI is naturaly protected with a diode on its live so i thing this has either been compromised by a short or has been by past by a short into another wire.I would be having a skilled auto spark check this out before moving on and costing you on more parts and causing even more damage.Good Luck


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