CB400 missfiring , won't start , hot battery ,

[hornetmike]

My sister came out on her bike today CB400 1994, first time this year and it kept breaking down. The bike was miss firing at low revs after a while won't start on the button, all the lights were flickering and when I took the battery out to put it on charge it was red hot.

Been told it could be rectifier , how do I test it ? Or could it be something else ?
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010

[Blau Zedong]

Probably a fucked reg / rec....you need to start it and measure the voltage across the battery. Shouldn't go above 14.5V when the engine is revved.
____________________
18:54:48 Rob Fzs: jews don't give away stuff for free

18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[salty21]

multi meter over the battery with the engine running, should be around 14.5v give or take, thats what my 94 cb400 is anyway and that runs fine. My guess is yours will be showing over 15v but im no expert.
____________________
04 NSR 125(sold) ---- 03 CBR 600rr(sold) ----90 pan euro ST1100 '' ----02 CG 125
94 CB400 Super Four ---- 2000 VTR SP1 (sold) ---- 08 ninja p8f(sold, meh) ----05 CBR600rr

[hornetmike]

cheers for your quick replys I will try that tomorrow.
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010

[hornetmike]

Is reg separate to to rectifier ? Why are they ?
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010

[Blau Zedong]

[Vincent]

I take it the bike is a CB400 Superfour? Early Reg/Rec units, (the ones without fins), were troublesome. You're lucky the battery didn't blow up. I think it's situated behind the tailpiece on one side. New replacements vary in price from £35 to £78 There are plenty of used ones available from various different Hondas, just make sure you get the "finned" one.

[hornetmike]

Cheers for your help tested voltage today and it was 17v when reved lightley with lights on which I guess is bad . The reg/rec is flat no fins so time for new battery and reg/rec.
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010