hey guys i wana know wat is the difference between the lrp spec 1 .28 size engine and the spec 2 and 3

i am getting one and would like to know if its worth keeping and modding or just chuckin it on ebay....

its never ever seen a drop of fuel

and how long will it last before it blows up and is it reliable and easy to tune.....

i have a TTR pro 21 bx-r in my savage which i have ported myself on about the 25th litre and its still been goin strong for the past 30 litres since the porting and starts first pull every pull,has had some lean times and some times without an air filter lol

still goes strong like a battle tank and flips my savage onto its roof every slam of the trigger....and i mean with 40 series moabs and a wheelie bar with the biggest wheel on there and lowered about 1 inch ground clearance!

any help with the lrp will be much appreciated