classic motorcycle forum

hi there no wonder i can,t get my c15 started i think i,ve got a serious electrical problem i hope someone can advise me differently, so here goes. i thought i,d got a spark at the plug (well i did have but it didn,t last) i have just charged my battery up before trying it on the bike, with a 6v tester accross the battery termnals its fine but when i turn the ignition switch to either on or emergency start position (new switch  and i,ve tried the old one as well ) the tester light goes  really dim and the c.b lead( black and white) is only sometimes  live and when you open the points by hand you get a spark when the spark plug is earthed to the engine then it just disappears until you disconnect everything and start all over,then you get a spark for a little while. only the battery power has all but diminished now.i have tried two coils , &  two dizzies. i thought maybe the wiring harness was shot but took it off the bike and tested it on the bench putting a tester to each end of the wires and all seems fine except the small rectifier post was only live some times (i,ve wire brushed it all of and now that seems good as well. the only other thing i,m not sure about is the three wires out of the alternator as they  could be connected incorectly but would this really make a big difference,as i thought they were for charging and lighting only. any advise would be helpful,thanks folks

hope you clever people can help. i,m on my first rebuild and posted some questions ages ago and then decided to start from scratch because all i had was a bike that wouldn,t start but just backfired.  Right  the crank/conrod is all good.its had new piston rings and the barrel is sound.(so far so good) i,ve used another cylinder head as i thought there  may be a problem with the valve guides in mine  (although its old it all looks good so i,ve re ground my valves  into it )and also used another rocker box. the valve timing was set on the bench  before the cylinder head was refitted so i believe that its spot on.  its now back in the bike and has really good compression and bright spark. but its not even firing. i don,t think the plugs getting wet . i,ve had the carb to bits on the bench and it all looks o.k. but when its fitted to the bike and  you turn the petrol tap on it floods everywhere through the tickle valve.i,ve just removed the rubber connection between the carb and the air filter and when you turn the engine over petrol is coming out of the carb where the rubber joins the carb.any help would be appreciated.

thanks for your help guys, i,ve got a bit more to try now.i,m not givin up but just havin a rest from it till i,ve got more time on my hands

thanks for your replies, i only ran it for a couple of minutes and now i can check , your suggestions as i am learning all the time. cheers.

can anyone help please? i am working on my first renovation product a 1965 c15 and am nearly ready to give up. i have fitted new valve guides and have good compression ,i have changed the dizzy & coil and have a good spark at the plug . i believe the timing is correct as i have done it that many times but it still won.t start. all it does is backfire into the air filter. any ideas would  help my other problem is actually kicking it over.  with the plug out it is easy but with the plug in the kickstart seems to just slip without the engine turning. any help will be really appreciated,i thought this was going to be a nice retirement project but it has become a real windup.

can anyone help please, i cannot get a spark on my c15 (distributor engine) am i right in thinking that when the ignition is switched on (i have fitted new ignition switch ) that the black and white wire (c.b. side of the coil )should be live  cos it was at some stage but not now . should i be checking the ignition switch ? or the wiring loom. any help would be much appreciated ta.

very helpful thank you