can anybody help please

i have bought a st70 1976 model 6volt and a cub 90 r reg 1997 model , will the engine go straight in and if so what would i have to do to electric system to try and keep lights 6volt. any infor is big help thanks lee

Hi There
A couple of observations the cub engine will have 12 volt electricals so it would be better to uprate the ST to a 12 volt system avoiding starting and maintenance issues, also the lights on my 74 ST 70 dim to dangerous when at junctions so I would avoid the 6volt unless you want a truly original bike, just the engine electricals are a lot of hassle, i would go the 12 volt route also if you have the cub you should be able to modify the wiring loom to fit your ST
Regards Tufty AKA Clive

The C90 engine will fit your ST frame perfectly.

As far as I remember, all C90 engines are 12v CDI.
Only the old (70's) C50 and C70 versions had an 6v points ignition.
If you really want to stick with the 6v system (as I do, nothing beats the speed of a high tuned points ignition!) you're choices are limited:
- swap the crank for a 6v L-type (lots of work, but a smart thing to do on an old engine without known history)
- bolt on a very expensive 12v tap 6v output rotor

If you decide to go with 12v after all, you've got to change/ad:
- part of your wire loom
- battery
- light bulvs
- CDI
- regulator
- horn
- sometimes ignition coil and switches, but this only in very rare cases

Quite a lot of info concerning this type of transition can be found on this forum.

thanks for your replys i will let you know how i get on. thanks lee