CDI Kit for stock ST70

I was reading an old thread where I saw a CDI kit recommended for increased performance as a fairly inexpensive and not too time consuming mod. What exactly is a CDI? I googled it and came up with an electronic ignition. Looks like the stator on my bike except with more wires and a little black box with more wires.

Where would I get one for my 1970 ST70 Dax?

Any ideas on where to get one and how to install, is appreciated.

How does it gove you more torque or speed/performance?

You have two problems 1- A 1970 will be 6v and 2- you will have points, not electronic ignition.
This is the type of unit http://www.pitbikeparts.co.uk/race-bike-p-277.html
Sorry for the bad news VMax

In fact, you are able to install a CDI ignition using the original flywheel, both for the short and long crankshaft.
If you're intrested, I'll get you in contact with the guy who makes them.
The good thing about them is that -unlike with regular CDI ignitions- the output is 6v.
So no need to change the battery, lights, horn,... for a 12v version.

CDI doens't use points for timing, but magnetism and an electronic impuls.
Far more reliable and maintenance free, but less exiting and harder to tune up (or it will cost you a lot of money)

Waynus wrote:In fact, you are able to install a CDI ignition using the original flywheel, both for the short and long crankshaft.
If you're intrested, I'll get you in contact with the guy who makes them.
The good thing about them is that -unlike with regular CDI ignitions- the output is 6v.
So no need to change the battery, lights, horn,... for a 12v version.

CDI doens't use points for timing, but magnetism and an electronic impuls.
Far more reliable and maintenance free, but less exiting and harder to tune up (or it will cost you a lot of money)

It will cost me a lot of money to tune up? A little confused here. If the CDI is doable for my 1970 ST70 And is not a ton of money and can be installed by a lay person like me then I am interested to see what it costs and how it goes in. Thanks a lot.

If you don't care about the fastest ignition available, it will set you back around 80-100£ for the points to CDI conversion.
It comes with instructions, so if you can dismount the old ignition, you're about half way there.

Your ST is already 10mph faster than mine. I'm not sure how fast you expect it to be? My C90E Cub will only do 50, Innova 125 does 60-65. If you look how much Waynus spends to get to 65( and he is the acknowledged expert on these matters), it would be cheaper to fit a chinese 110cc engine (about £165 in the UK).
You are lucky and CT90s are available in the USA so maybe buy a rough one and do an engine swop? Vmax

VMax666 wrote:Your ST is already 10mph faster than mine. I'm not sure how fast you expect it to be? My C90E Cub will only do 50, Innova 125 does 60-65. If you look how much Waynus spends to get to 65( and he is the acknowledged expert on these matters), it would be cheaper to fit a chinese 110cc engine (about £165 in the UK).
You are lucky and CT90s are available in the USA so maybe buy a rough one and do an engine swop? Vmax

Thats interesting because I would have thought my 1970 ST70 would be slower than it is. I know no speed mods have been done and going up my street I reach 50MPH no problem. Hmmmm..

Maybe something wrong with my speedo , just a 72cc standard engine doing well I suppose. I will probably stick to the points I have, going to replace them as soon as the flywheel puller arrives. Then either replace the card or rebuild the carb.

The carb is starting to disintegrate inside the little filter on the side.

40mph is indeed the normal top speed (without back wind, downhills, or acrobatic poses) for a standard ST70 engine.
Note that there are different versions with smaller/larger valves, different flywheel, stator plate, spanner,...
Especially the type of ignition makes an important difference, and the correct set-up and general condition of sprockets, tyres,...

If speed and budget is an issue, the chinese engines are probably the best way to go.
But they are just not mine cup of tea.
Or... you should get a Jingcheng DX90 (old type) engine, wich are easy convertable to 6v points, and are very reliable and fast enough.

Waynus wrote:40mph is indeed the normal top speed (without back wind, downhills, or acrobatic poses) for a standard ST70 engine.
Note that there are different versions with smaller/larger valves, different flywheel, stator plate, spanner,...
Especially the type of ignition makes an important difference, and the correct set-up and general condition of sprockets, tyres,...

If speed and budget is an issue, the chinese engines are probably the best way to go.
But they are just not mine cup of tea.
Or... you should get a Jingcheng DX90 (old type) engine, wich are easy convertable to 6v points, and are very reliable and fast enough.

I think I am quite happy at the moment with my speed. I love the originality of my stock baby and don't want to do too much to her that makes her so modified she looks different. With 50MPH I am more than pleased. I am just amazed it goes that fast at all considering the average and the age of mine. Condider myself one of the lucky ones!