Used engine, weird spots, awkward sputters.

[LukePeoples]

So I just installed this engine yesterday, it was a "Beach Dweller" as the previous owner said, and there are awkward spots (as seen here http://photos-d.ak.fbcdn.net/hphotos-ak-snc1/hs030.snc1/2584_60293203809_553283809_1493723_5144161_n.jpg ) and when i reach full speed, most of the time, the engine stops accelerating, and slows down, as if i had hit the kill switch. spark plug is new, air filter is fine, chains arent snagging, and brakes are fine. so what is causing this bike to barely reach 15 mph... my other one, which is the exact same engine is maxed out at 35....

 

[LukePeoples]

sorry about the double post, but if I do need a new engine... where would i buy just an engine, because all im seeing is kits, and since i have a 66cc "Raw" engine... would an 80cc engine fit all my parts?

 

[rjs5700]

The spots are just oxidation on the aluminum from the salt air at the beach. Not really a problem except cosmetic. Don't give up on that motor as it may be as simple as carb adjustment, or dirt or residue in the system. If it sat unused for any length of time it could be either one. Flush the tank, clean the carb and see what happens. BTW the "80cc" motors are actually 66cc advertised as 80cc.
Good luck.

 

[LukePeoples]

so, the engine going vroom VRoom VROOM vroom vroom is because i have bad fuel?


edit.
i have an extra 66cc engine, so if ill switch these two, and then see the changes in quality. i think i just got a bad engine.

 

[rjs5700]

It's possible. The slightest bit of sludge or debris in the carb could restrict fuel flow and cause the problem.

 

[LukePeoples]

carbs fine. new fuel, i think ill just change engines and see whats going on tomorrow night.