Electrical help/advice please

[Guest Amigo]

A few weeks ago my honda regulator/rectifier handed it's notice in (with the fried battery to go with it).

After a bit of research on the net, a yamaha R1 unit seemed the best way to go. I bought one from that auction site, and fitted it following the instructions from various sites. I also fitted a brand new battery. It worked a treat (for some reason the X seemed to run better as well!) except for the rectifier getting hot. On friday whilst parked at work one of my lads came out with the 'your bikes on fire' line - and got the usual f**k off reply. Turns out it was! The R1 rectifier was quite happily burning itself out. On inspection the back of it was touching the subframe.

I've bought a pattern honda rectifier to refit. My questions are;

Why did the R1 unit burn out? What do I need to check electrically before/after I fit the new unit?

I'm getting at more than a little pissed off at stupid (& expensive) electrical problems that are ruining what is a great bike!

[fast_eddy 712]

You'll have to check the output from your alternator to see if it's overvolting, there is a procedure to follow in the shop manual. That along with all of the wiring concerned, you'll be looking for good clean connections etc.

Do this before fitting a new unit...

I can't comment on the R1 unit you fitted... I don't have a clue about its suitability.

[Guest fe5ta]

The first thing I would check is the earth wiring not just the strap from the battery to the frame but all the earth wires on the loom, does your bike keep blowing bulbs? as this would point to a bad earth and or over charging.

Regulator/rectifiers do get hot, sometimes nearly too hot to hold, that is because of what they do, all the extra voltage and amperage that they filter out needs to go somewhere and that is converted to heat.

As Eddy said you need to check your Alternator outputs and the rest of the charging circuit and connectors.

As for the unit touching the subframe I personally doubt that would have been the cause of the problem, was the bike still running or had it not long stopped, say 5 mins, when it went on fire? It would suggest that power was still going to the unit for that to happen and if the bike was turned off the only source for electrical power is the battery which would point the the charging circuit being faulty after the reg/rec.

[Guest Amigo]

You know my bike quite well! When I first had it, it blew bulbs on a regular basis. That stopped, but sometimes the headlight bulb goes very bright when I first switch it on, it seems to settle down to 'normal' after a while.

The 'bit' touching the subframe was the resin part on the back of the rectifier. The bike had been stood for about 5 -10 mins, I'd been to the chippy for the lads (a 5 mile round trip), it was switched off and the key was out.

Looks like it's out with the voltmeter, wire brush and electrical grease for me tonight!