[christnunn]

Hi all, hope this helps someone if they have this issue, as it took me a while to diagnose and I didn't find it mentioned in any forums.
My 2002 954 fireblade was intermittently cutting out at high rpm, above around 10k rpm. The rev counter dropped and FI indicator flashed up, with the red error dash light. This was only for a second or two then back to power again, but was pretty violent! It tended not to happen if the bike had been running for a while so I assumed plugs at first... also there was no error code logged.
Long story short it turned out to be the regulator rectifier as when I checked the wiring under the seat (by the ECU) one line showed charring at the connector indicating overload in that line.
So before changing your plugs and fuel filter check the RR first, Haynes manual gave the values for the stator and wiring checks but the RR can't be checked at home. I bought a new RR from MPW in the UK and it was £30, so cheaper than the plugs, and fuel filter. Still they would have needed doing at somepoint!
Good luck

 

[oldbastard]

Unfortunately that's usually only half the story, because the RR is pretty heavily influenced by what is happening to the stator. The normal sequence of events is that the RR gets too hot dealing with the excessive output from the over-engineered stator, gives up the ghost and USUALLY takes the stator with it. I would check the stator if i were you,either by measuring the 3 resistances between each of the 3 wires coming from the stator ...engine not running obviously..or with the engine running, check the voltage between each of the 3 wires...they should be the same and >30V.
Or just smell the oil. If the stator is fried it makes the oil stink of burnt insulation.
Maybe you were lucky and only lost the RR...

 

[christnunn]

Hi mate, thanks that's a good point. I did check the stator resistances and all were within spec, but I guess it's worth doing before putting a new Regulator Rectifier on. Could an out of spec stator damage the RR or is it only usually other way round?

 

[oldbastard]

I think that it can work both ways. I chomped through several stators and RRs ,both Honda and others, before deciding to de-rate the stator by rewinding it with fewer turns on each pole and thicker wire. That was done 15 years ago and is still going strong, although with the lower output you need to fit LEDs . Its not a job for the faint-hearted. You might be able to achieve the same effect by fitting a reduced-strength flywheel,I.e. weaker magnets. They are probably still available from racing equipment suppliers,but I'm afraid I don't have any links.