Tech reg/rec Q - looking for facts not conjecture

[manicguitarist]

Hi folks!
The reg/recs are weak on these bikes. I know that.

Mine is running a replacement one - but still - don't wish to stress it further.

Anyway - the question is - what is it that the reg/recs are suffering with? Is it power through-put - i.e. they can't handle the load and current drain that the electrical system puts on them - or is it that they cannot dissipate the excess energy that the generator makes?

To put it another way - is it that the electrical system (i.e. the things that *use* power) is over specified with regards the reg/rec - or is it that the generator is over spec'd?

Why am I asking?

Just been on another overnight trip on the RVF - had a great time. 500miles and a happy rider. But oh my it was cold. My hands properly hurt.

This is the first bike I've had that doesn't have heated grips - so would heated grips make the reg/rec more likely to fail (because of increased current draw) or less likely to fail (because the reg/rec doesn't need to dissipate so much extra energy).

Please no conjecture here - yes the reg/rec needs a heat dump - and when it gets too hot it will fail as things melt internally - but is it the supplying of current to the system that is struggling or the getting rid of unwanted energy that is struggling - both of those will cause heat.

Thanks.

M

[Dynamohum]

Practical sports bikes mag recently had an article on wiring modifications for older Honda reg/recs which might prolong the life of it if you have concerns.
I use r6 reg/recs on two bikes so far so good but basicly its old technology shunt type regulators just larger with more heat dissipated that hopefully last longer but imagine will eventually fail just like the shunt type on my old 4000mile 675 triumph striple did

The fact or fix is to change to a MOSFET type reg/rec rick oliver sells them for nc30/35s job done .

[magg]

More electrical load (headlights always ON, heated hand-grips) gives less rect/reg heat, better thermal transfer to chassis gives less rect/reg heat.

Old style SCR shut rect/reg (OEM NC30, SH part # prefix) generates most heat, newer FET shut rect/reg (FH part # prefix) appear to generate significantly less heat and do not appear to require heat transfer to chassis, RO rect/reg is completely different design series rect/reg which will get hotter with larger electrical load.

Is the 675 a SH or FH type rect/reg, if SH does it have good thermal tranfer to chassis?

SH type rect/reg off later model large capacity bikes can handle more power and thus more heat provided the heat is dissipated somewhere.

Good thermal management of adequately current rated SH type rect/reg should give reliable serice.

Can offer suggestion for wiring mod to improve the inherent wirimg deficiencies of the Honda OEM (applies to other manufactures too) if interested, PM me.

[Dynamohum]

Magg the 675 had a large heavily finned SH type bolted to a plate for good heat transfer mounted betwixt the shock and lower crankcase out in the breeze and still failed .
I believe they changed to the other type after 2010 after an influx of warranty claims for this problem .


The wiring mod you have does it involve running pos/neg from the regulator direct to the battery as PS magazine have ?

[magg]

Answer to wiring question - yes. The wiring mod extends battery life by giving it a full charge, battery voltage needs to reach at least 14 volts to be fully effective and may not with the wiring employed on many models.

I doubt your 675 rect/reg was mounted using thermal transfer compound and the flatness of the plate may not have been that good. Is the mounting plate part of the chassis?

These features are not part of the mass production process, would cost too much, like the wiring mod, and provided the rect/reg gets beyond warranty period, then no problem for manufacturer.

If thermal tranfer compound is used and the mounting surface is flat and structurally connected to the chassisa, the reliability of an SH type rect/reg should be comparable to the FH type. FH type are now popular with manufacturers because they are very reliable when mounted free standing.

[manicguitarist]

So - kinda back to the original Q - what is it that makes the regulators so weak on the 400s? Is it the wide rev range that they have? From comments above it seems that the issue is that the generator produces too much power for the regulator to dissipate when high revs are being used. Is this the case?

[magg]

Thought my opening statement covered the question, however happy to reiterate; heat generated internally by SCR type rect/reg that is not adequately dissipated will cause eventual failure.

400 rect/reg are no more weak than other SCR types, all SCR types suffer from heat dissipation issues due to OEM mounting methodology.

Inadequate current rating would be a rare complaint but heat dissipation is a common issue. Some rect/reg have finned surfaces to increase area but it appears to be more cosmetic than useful. All SCR type rect/reg will have improved reliability if mounted for best heat dissipation and the bike is operated with maximum electrical load ie headlights on.

FH and RO series rect/reg types are most reliable because of the lower internal heat generated, which does not require a well engineered heat removal mechanism.

[Neosophist]

So - kinda back to the original Q - what is it that makes the regulators so weak on the 400s? Is it the wide rev range that they have? From comments above it seems that the issue is that the generator produces too much power for the regulator to dissipate when high revs are being used. Is this the case?

I don't agree that they are weak, just they don't tolerate a lot of abuse so are easier to kill than a biger unit.

Not been addressed is that old batteries do not take charge as well as a new battery. Not keeping the battery charged up will allow the battery to degrade quicker, this heats up the reg/rec.

My latest 30 still has the original reg/rec on and hasn't failed yet, battery is replaced every couple of years and always kept charged up.

As magg has pointed out, its generally assumed heat is the biggest killer of these, the poor battery will cause it to heat up more.

If you fit a larger reg/rec make sure it can transfer heat well if its not in a place where it gets a lot of airflow.

Also ensure your battery is in optimum condition to prolong the life.

[Variablevalves suck]

The sh type reg/rec is used on pretty much every bike built between 85 and 2005, you find some bikes have more problems than others probably due to poor cooling, weather ingress etc.
They have cheap type connectors that are fitted and forgotten about, these cause the wiring to run hot etc
Poor earth, oxidation in other parts of the wiring all add up to problems.

You will be ok with heated grips if you give the electrical system a good mot, if you are prepared to spend a little you can convert to a water proof connection at the reg/rec or even better is to fit a 2008 cbr 600 (F008) reg/rec they are rated 10amps higher than the standard part but are only a few mm larger.

[manicguitarist]

Is the cbr reg/rec a direct replacement? Money isn't really an issue here.