If your racebike building, you clearly 'do' bikes .. so ...
How about ....
Battery / leccy problem ...
When starter motor draws ?? 30 / 50 amps ??? when spinning..
Ignition system is not getting juice as not enough voltage going to primary coil to give secondary coil the 12 / 16000 v output ??
Low battery ?? [does it spin up fine & fast ???]
Is there a lose connection on the coil / LT Line, and when starter spins, the high resistance joint gets no current flow as the starter is such a low resistance / high current path ?? So basically it all goes that way ??
Is it $hite at starting even when warm ???
If spins up good ...
Does it bump off good ..... [when warm, so choke carb prob's don't hide prob'] ???
Pull plug & see if spark at all when starter motor spins ???
Does plug spark change [for the brief moment] when starter is released
Deffo sounds electrical ??
?????
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Blue - DT 125 RE - '04 - First Of The Leccy Start Lanza'Like Bikes !
Stomp is cool ... 55mph ! My old 50 would [will !] just about do 50 down a fookin big hill
Your 'X' Earthed YPVS wire out in speedo ...
Pipes on it's way ! Would expect another lift in performance once you get rid of the CAT Xpanny chamber, i aint' seen inside one, but Pea tells me that the CAT matrix pretty much fills the wide part of the pipe So it's never gonna be as effective as an empty Xpanny chamber.
Are you planning on doing the Reed Valve Block Mod's ? And removing the Plaggy bottle near your L/H foot ?
Not spoken to anyone who has done the Reed Block ? [Will post question up ]
And general wisdom seems to say the plaggy bottle on the N/S frame is some kind of restrictor ? But im yet to get a full Xpaination of how it restricts bike ????
[Not the Plaggy Bottle on the top of the inlet F'Mould .. that's deffo' a boost bottle & helps the bike drive from low rev's]
If its screwed all the way in it will run way too rich and cause possible plug fouling. NEVER run it without the screw cos the motor will be way, way to lean and will eventually seize You mention it runs better with the choke on.This should not be the case with a warm motor so check for things like intake air leaks which will cause lean running If its not running right at 1 1/2 turns a good carb strip and clean is the best advice i can give