im new to bike engines, cbr 900 893cc 1994

i have had a megablade westfield for a few weeks now, and gone out for a short run tonight as roads were dry,

lucky i was just 200m from home, and the car died at a junction, wouldnt start so pushed it home.

charged the battery up and started the car up and put the volt metre and reads 12.5 volts running and slowley dropping, even more when lights are on.

so no charge to the battery.

i have read up either alternator or rectifier, how can i test these to find the fault?

looking at the location of the alternator case its right against the fire wall but just enough room to undo the bolts, will this just slide out?

any help please?

is anyone local with a spare rectifier so i can test this?

Nick,
There is a test procedure for checking out the rectifier if you have a decent multimeter. The Haynes 'blade manual describes this well. Otherwise if you want to borrow my rectifier (mines a 919, but I think they are the same unit) to try it that's fine, I'm only down the road.

Chris

PS: have a look here, click on the 'fault finding guide'

Clicky

[Edited on 5/1/12 by Proby]

Cheers mate. It's enoying I had it booked in for it's MOT on Saturday.

Where abouts in wolvo are you mate?

U2U sent!

It very unlikely to be the alternator itself.
Likely the wiring or connectors on the way to the regulator, or the regtulator itself. So save your time and get to the regulator plug and measure the resistance acros all three of the big pins on the plug wiring to the alternatoer They should all read the same.
You may well find the plug itself burnt as you look at it.
As written so many times here before the regulators arent the best, but can be replaced with a more durable Honda 250 one with a better heatsink

Yeah looks melted and smells burnt. Had a bugger to disconnect it.

Honda want £150 for a new one. Any cheaper alternatives ?

Links or eBay item number would help please?

Thanks again guys for your help

Those fh012 or fh014 regulator/rectifiers are the mosfet ones and are great, these are on a few modern bikes. In my case it doesn't get even warm.

You might have to change the plugs.

Here is a useful link.
http://www.triumphrat.net/speed-triple-forum/104504-charging-system-diagnostics-rectifier-regulator-upgrade.html

New Rectifier Honda CBR900 RRN/RRX Fireblade 92-99 | eBay

Here is a cheapo original type.

There are alternatives as stated above, or even fit a 12v cooling fan from a PC above it to try and keep it cool......

[Edited on 6/1/12 by Proby]

You think a cheaper one will be more likely to go again? Yeah I thought wil get a pc fan to cool it and mount on the top

There is a bike shop selling new ones, heatsink for £60. So I can pick up tomorrow. They sell them on eBay.
Do you think an aftermarket heatsink is worth that much? Or just get a used original part for £30?

Honda Superdream CB250n Regulator/Rectifier,Fusebox | eBay

These are the ones to go for price/quality/heatsinkness

I could selll you a spare but that's a good price

Cheers guys new rectifier and charging 14.5v now