HELP! Speedometer keep resetting itself when engine starts!

Do a search with your very subject and you will find that you need to replace your spark-plug wire. I'm not sure on specifics about what wire is best but the threads you find will have that info.

And welcome to the best site for motor bikes on the web.

This thread might have the answer to the wire:
http://motorbicycling.com/f4/resistive-plug-wire-question-26578.html

I haven't gone through the thread, just glimpsed at it and it had numbers and mentioned speedometer somewhere. LOL

If my memory serves correctly I think someone said to use a magnecore type lead.
But if failing that see if you can find yaself a SIGMA branded speedometer they are a little more expensive but worth it Mine was $39 and its never skipped a beat after being wet, crashed on, left in the sun,etc.
Remember to get yourself a leaded one when/if looking.
I wasted a whole lot of time and money once before trying just about everything and I can tell ya now save yourself the headache and get a good quality one its just a PITA when ya try all this stuff and it doesnt work out.

But in saying this I'd try the lead out ya can fit an 8mm one in but you might just need to shave abit of the insulaltion off so it goes back in the CDI. I superglued mine in but just a personnel preference thing I guess.

Glad it's working for you now.