So I just got my CB125 running well enough to take it the 20 miles to work (or so I thought). Made it there just fine, halfway home I hear a pop/crack, and the bike locks up. Tried to kick it over, and the engine was frozen.
Got it home, and took off the stator cover, and was able to spin the engine 359 degrees CCW, and then 359 degrees back CW, but it won't make a full revolution. Timing chain looked fine. The obstruction is definitely in the top end.
So I pull the spark plug, and the whole end is disintegrated! It appears that it melted and a piece must have dropped into the cylinder. Ugh.
So, my question for you fine folks is what could make my plug so hot in the first place? I come from a 2-stroke background, so I don't know if the same rules apply here. Could the timing being too far advanced do it? Carbs running lean? Air leak at the intake?
My battery melted a few weeks ago, so I ditched it and the bike still ran with no battery, and the lights and blinkers still worked. Took it out last night, and the bulbs blew. So it seems as though I need a voltage regulator. But that wouldn't have any affect on plug temp, right? I assume it's just a coincidence, but figured it's worth mentioning just in case.
I got the bike it had been hacked up and rebuilt from the frame up as a cafe, and it's been converted to 12v.
Thanks
