Is this your Narco Buchpiolit bike?
That won't be friendly to motorize.
You
might get that Skyhawk in there if you spin your head 180 so the plug points forward.
The seat post angle is too straight up and down for your carb to sit level with the back mount square to the seat post, which it MUST be, so you will need make a new carb intake manifold, most likely an offset Z so your throttle cable will clear the top bar.
You will need a new front mount, measure the diameter and you can get a Large Universal Front Mount from
http://sickBikeParts.com with the correct size muffle clamp.
And then of course you have a back disc brake...
IF the engine will even fit I'd go with a jackshaft shift kit like this similar frame geometry bike with disc's.
A 2048 wide pic is
http://kcsbikes.com/bpics/2_Surley2SmuleR-2048.jpg
The other side is
http://kcsbikes.com/bpics/2_Surley2SmuleL-2048.jpg
That has a modified intake to keep the carb level and the front mount I told you about.
Of course you could sacrifice the back brake and mount a direct drive sprocket to it's mount, or get a TopHat adapter to try and keep it, but why?
It's great to be able to use bikes gears for the engine, and you NEED 2 brakes on ANY motorized bike.
Last but not least, everything on your handlebars has to go.
Loose the front derailleur too, you can manually put the chain on whatever front sprocket you want.
Ideally your clutch lever and a rotary 7-speed rear derailleur shifter are on the left.
The rotary throttle and dual pull brake lever on the right.
Just a heads up and some tips to get around the issues.