Hello to you cbr guru's and officianados. Recently purchased a 1000f on 90 plate, the bike runs okay etc.. but i have a starting problem when cold. The engine spins over at an okay speed on the starter but as soon as you tickle the throttle open or give it some choke the engine struggles like mad to turn over, close the throttle or choke and after a couple of revolutions the speed of the starter picks up again. It has a new battery fully charged on my works battery charger, starter has been swopped for a known good one all with no difference. I checked earth connections and even tried another jump lead from engine casing to battery - terminal. checked wiring from crank pick up to ignition box and all okay. It sounds like timing but air gap on pick up fingersand rotor seem okay (but they do vary from one finger to next, guess this is for ign unit to know which cylinders to fire)not sure what they should be exactly. It sounds to me if it was a car that the timing is to far advanced when cold but there is no adjustment that i can see. The plugs were changed about a year ago and the bikes done 1500 ish miles since. Gaps are okay and compressions good. Any help apreciated. Once started with car jump box will be okay all day. cheers all !!!!

 

Advanced timing can be hard on a hot motor, but I think less so on cold. I am leaning towards the starter. Can you see how many amps it draws during the start? Maybe even the lowest voltage during start.

Good luck.

Edit: I don't know if plugs would matter as far as the speed of cranking, my guess is no.