Originally Posted by moonerdizzle
if you want your motor to last as long as possible, when you get it, tear it apart, clean it out, found casting sand in all the cases ive bought, replace the crank bearings with better quality ones, also replace the wrist pin bearing.
I'm sorry moonerdizzle but I couldn't disagree more.
Suggesting a rookie break open his new motor case is more likely to leave him with a broken motor before he even tries it than make it better, besides if you buy a good motor like a Skyhawk to begin with all that is already done right to begin with.
Casting sand in every motor you have bought? What the heck are you buying?
As for real
gas mileage I just figure on 80 MPG because for the most part they are ridden balls to the wall all the time.
With an expansion chamber maybe 100 because all that wasted fuel that exits the cylinder is forced back in to be burned.
As for how long the motor will last that is best measured in Hours not Miles like they do heavy equipment, change break-in mix at this may hours, pop the head, inspect the cylinder and re-torque it on at at that many hours, etc.
I know that is totally unfeasible but if you really wanted to know that would be the way to it.
Treat it right from the beginning and you can measure it by worn out tire replacements and 2 or 3 times without any major problems is certainly possible.
As far as how long the motorized bike as whole will last that is as much the bike as it is the motor, I mean come on, it's a bicycle ;-}
I have no first hand knowledge of this, my personal ride is always something new but one of my very first builds 2 years ago with a Skyhawk rode by a pair of guys almost constantly for a year and half before it was stolen went through 2 sets of tires, 4 plugs, a tailpipe, and some miscellaneous other things like a clutch cable but nothing inside the motor.