Greetings all

I have a 1990 CBR1000FL, and recently it has been intermittantly difficult to start, hot or cold. Once running, it runs 100% fine, which leads me to believe there is probably nothing wrong with the ignition box. I have tested both the pickup coils and HT coils, plus the side stand switch with a multimeter as per the manual, and all measure within specs, so I don't think there is anything wrong there either.

I can also bump start the bike OK every time, it just won't start on the starter. What happens is the starter will turn the engine over fast with no choke, and this gets a nice fat spark from the plugs. But as soon as I pull on the choke, the starter cannot spin the engine over very fast at all, and at these slow turnover speeds, there is no spark at the plug(s).

NowI have changed to another starter, and the same problem exibits. I also have the same problem when my battery is freshly charged, or when I have a pair of jumper leads attatched from a good car battery (should have heaps of grunt)

Question - Why does the starter not spin the engine over at the same speed with and without the choke on?? Is there some sort of chamber closing that affects the compression??

Question - Any suggestions as to what the problem may be? I've tested as far as I think I can without a result.

Thanks

 

If you are really sure that there is not a battery problem, it could be the starter beginning to give up or that the starter relay has got some contact resistance. First, check all electrical fittings in the starter circuit from battery to starter and the battery grounding. I have no idea if the starter is prone to wear. I would start to check and clean all electrical connections in the starter circuit. The engine tightens up when chocke is on due to more fluid in cylinders, there is no purge function associated with the choke.