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[Ade]

Royal Enfield made a Classic Bullet 500 ES (Electric Start) CTD. Can anyone please tell me what the CTD stood for? I think it was something to do with an ignition and electrics up grade. Many thanks, Ade.

[Gwilly]

Hi Ade. i'll have a stab as no replies given. i think you may be getting your letters confused. Do you mean TCI and CDI? These do indeed signify types of ignition fitted as the Bullet was developed over the years. Both use a sensor to trigger a transister switch which has replaced the old points systems. TCI (transistor Controlled ignition) which switches the usual 12volts on and off through a normal inductive coil just like points but with better control. CDI (capacitive disharge ignition) fires  maybe 250volts into a low resistance coil or transformer which steps up the output voltage to spark at 30-40,000 volts. hense dont catch hold of the HT lead whilst engine running. I'm sure an automotive electronics engineer will be along to explain better, but i think thats the gist.


cheers gwilly  

[Alan R]

Hi there Ade--------I think it might have been a shortening of an Indian  Engineering phrase ( Ask Hemant for the full wordings) which looseley translates as }-----"Self Diss-assembling Spragg" . A typo during the design stage at the Chennai factory which nobody picked up on hence all those spragg clutch failures a while ago. On the other hand I must keep off those mushrooms !! I think Gwilli's correct. The CDI systems use a large   capacitor instead of a battery---being fed and timed direct from the generator.  Sports guys use them a lot, no need for messy battery. I had that on my 250 Montessa Grass-Tracker back in the 1970's. Was plagued on a hot day by "Spurios UV emissions---" An HT coil actually IS a transformer. 

[Ade]

Thanks Gwilly and Alan R for your replies. I think Gwilly you were close to the answer in a round about way. I've done some more research and I think it should be STD not CTD, which I think stands for Standard (not Sexually Transmitted Disease)! Ade.