Re: Newbie from UK needs help choosing engine, please help.
I dont think your weight would be at all an issue with either of these kits - personally given the deals on the table I would go with the one offering free parts..
So far as power output - properly run in they would both be fairly similar and for about another £70 or so you could fit up a jackshaft kit and have a multispeed bike.
It also depends what you want to use the bike for as to what works for you. If you want something fit and forget the commercial engines are probably best such as GEBE/Staton and others such as the DAX Titan but those are all overseas producers.
Be aware that you will have to use a higher oil mix when running in and also to keep an eye on fittings and fastenings etc - they can wriggle themselves loose from vibration.
You will need - in case the police get nosy - good brakes and lights and a illuminated speedometer/odometer etc - in my case I just got a little LED pinlight from poundstretcher and secured in in the relevant place - not pretty but it works.
Also - I hate to say it - but the 80cc and 69cc engines are generally one and the same - so you arent really loosing any displacement (it may be due to a different method of measuring the cylinder volume) with either choice.
Where are you in the UK by the way?
"....Look, no pedals... *thud*..." The mating call of the motorized-biker.
"RetroEagle" - 32cc Two-Stroke, Piped. 35mph on #13 gear. Reversed stem with springer fork.