Motorcycle Repair: yamaha, yamaha maxim 650, specific gravity

Question
i have a 1981 yamaha maxim 650 4cly.  recently the bike was running fine but i think i reved it too much in the exteam cold.  when starting the engine will start to turn but will not make a full rotation.  i have put the bike in gear and tried to back it up and it seems that the engine just wont go past that one point. i checked all electrical, ground, and the starter and all seem to be fine.  do you think it would help if i removed the plugs and filled the cyl with penitrating oil and let it sit a bit or am i just out of a bike?

Answer
Hi Brian,

Test battery voltage and specific gravity. Ensure the battery is in good condition and sufficiently charged.

Remove the spark plugs and try rotating the engine by wrench on the end of the crankshaft. You can rotate the engine as if starting with plugs removed, too, though the wrench method is recommended.

If the engine still acts as if it resists rotation, time to have a tech inspect the problem for you.

Let me know how it turns out.

Respectfully,
Mark Shively