My 300ex will run about 55 and when I get up to about 45 my bars start shaking. what could this be?

 

the steering stem bottom bearing could be bad also check the front end for an alinement bent tire rods bent rim etc...

 

Assuming none of the above-mentioned mechanical difficulties are present you may simply have a case of head shake which can be caused by certain aggressive tire tread patterns. In my case it was solved by the addition of a damper which was a big help in other ways also

 

well it may just be a little head shake.

 

Check your rear axel. You could have a out of balance tire too. On vehicles you pick up a vibration at higher speeds and if not corrected soon you could have eggs for tires.

 

Unbalanced front tires.

 

I think it may be unbalanced front tires. cause one is a litte more wore than the other.what is the easiest way to fix this?