Knock

[sprtrx300ex]

a while back i noticed a knocking noise comming from the engine after i rode for more than 10 min.. I got my valves adjusted and it still did it. I changed the spark plug. It hasn't knocked since(1 month ago). I looked at the plug and it was black(probably from the valve clearence. Well the noise it comming back again. I haven't changed the type of gas or anything(reguler unleaded 89), so i'm confused. I sure if i change the plug it will stop for a period of time, but will start again. What's the deal? Right now it is all stock.I know it is confusing but i apprciate all help.

try 93 for just one tank of gas and see if it helps

[QuadTrix6]

yea you should definetly be running 93 octane, 89 is garbage

[sprtrx300ex]

Do u guys think that 91 is good enough? Should I run the gas tank dry before i add the new gas? Should I also change the plug? Right now the plug is black.

yea 91 should be fine. try running the tank as low as possible then fill it up with 91. maybe sometimes when u r ridin real hard it is knocking.