Hello all, long time reader, first time poster.

I am having problems with my Honda 1996 CBR900RRT Fireblade which I'm hoping you can cast some light on.

During a ride out, the bike stopped and I discovered I had blown the ignition fuse. I replaced this and it blew immediately when I turned the ignition on. I also noticed that the battery looked swollen and had dampness in the battery tray. It had been dry for my ride out and the bike is kept in the garage so I assume this was battery acid. Once I had got it home in the works van, I found the battery wouldn't hold a charge so I replaced this and started doing some fault finding. I discovered that removing the black+white wire from the Ignition Control Module stopped the fuse blowing and allowed the motor to turn over, so I assumed this was faulty. I found a replacement of an equivalent bike and it now starts and runs without blowing a fuse. A small step forward. I was still suspicious of the swollen battery as this seemed a symptom of overcharging. I checked the resistances of the regulation rectifier as described in the manual and these were within spec. While idling the output from the regulation rectifier was 13-14 volts DC. As I increased the revs, this value also increased to over 18volts at 3000rpm. At this point I chickened out as I didn't want to damage anything else. On a video from Partzilla about diagnosing charging problems for a CBR600, the presenter tested the AC voltage from the alternator and measure 15 volts AC on his machine at idle. I did this for mine and was getting 13-14 volts AC on each of the 3 phases but this also increased with revs in a similar way to the regulator/rectifier.

So, my question is: Is this normal behaviour for the alternator and the job of the regulator rectifier is to cap the voltage to a max of 15 volts and transform it to DC? In this case can I assume the regulator rectifier is at fault? Or should the alternator just provide voltage up to 15 volts AC and the job of the regulation rectifier is just to change this to DC and the alternator is at fault?.

My instinct is the the alternator is fine and that the regulation rectifier isn't doing the regulation part of its job. Does this sound right?

Is it likely the regulator rectifier will have cooked the battery and damaged the Ignition Control Module?

I don't mind spending £100 if it fixes it but I don't want to keep throwing money at it unnecessarily. If the Regulator Rectifier is the likely suspect I need to source a replacement. Reading through the posts on this forum and others, there seem to be many options: Pay £20 on Chinese roulette, order a Honda OEM one, source a second hand one from the same bike, replace with modifications from a different bike, buy an aftermarket one from a specialist.

Even though I don't like spending money, I don't fancy the Chinese option if there's a risk of it damaging other things. It looks like avoiding Honda ones is recommended as they seem a bit of a weak point and using more robust ones from other bikes tend to require wiring or connector modifications which I'd like to avoid if possible. I've come across the RR58 from a company called Electrex which looks like a direct replacement. Has anyone had experience of this unit and would you recommend it? Do you have any other plug and play recommendations?

Assuming replacement Regulation Rectifier does the job, is there anything else I should check out before going for a spirited ride? I don't fancy getting stranded again or spending loads more money...

I know this is a long post, but I'd rather you had as much info as possible so you don't have to ask lots of questions from an annoying newbie!

Thank you all.

 

Welcome to the forum, sorry that you are having problems, albeit quite a common one unfortunately.
Yes you have indeed have a fried R/R, max output from the R/R is 14.3 to 15v and the rest dumped as heat by the R/R.
This would have indeed blown the battery if running as high as 18v, you were probably unlucky that it also took out the ECU, that is less common.
I would personally not go OEM or Ebay Roulette, Electrex do seem to have good press and where possible seek out a mosfet replacement (give them a ring to check) as the mosfets switch much more efficiently and as a result generate less heat and don't seem to go bang in the way the originals do.
You could add a voltage readout on the bike in order to keep an eye on the R/R voltage but should not really be necessary.
Do you run with a lot of accessories and or have fitted LED's as too much or too little load on the systems will cause problems.
Good luck with the fix and make sure to crimp and solder the stator wires then weather proof them as it was one of Mr Honda's failing and is generally the source of the issue by not fitting waterproof connectors.

 

Thankyou for your reply, your welcome and the reassurance that it is what I suspected.
The bike is completely standard, no LED's, no accessories, not even an alarm.
I'll give Electrex a ring as they seem to have a variety of compatible options as well as the RR58 and find out what the best recommendation is for my bike.
I'll let you know how I get on.

 

+1 on an electrex unit - you don't want to be chasing this down again in 6 months...

 

I would personally not go OEM or Ebay Roulette, Electrex do seem to have good press and where possible seek out a mosfet replacement (give them a ring to check) as the mosfets switch much more efficiently and as a result generate less heat and don't seem to go bang in the way the originals do.

 

Mods, can you please check this poster (marioeee3) for being a 'bot' as its a direct copy from my post above!

 

Haven't you heard that plagiarism is the ultimate form of flattery?
I'll take a look. You are probably correct.

 

 

Have you been able to get a replacement from Electrex and install it? I have a Superhawk that has an R/R that should be replaced. I guess Honda had/has R/R issues back in the mid 1990s.
Thanks.