The case on my 93 300ex is cracked at the lower left case half.Starts at the center of the left case half(rear of motor above lower motor mount) ,goes around the lower rear motor mount boss ,and down across the bottom of the case.Anyone ever had/heard of this problem.

 

Actully i had my 94' 300ex's case crack. Except, i thought i only had 1 crack, so i had it welded...no probelm, but then i found another on the opposite end !

 

Do you know what caused the case to crack and where was it?Also the location of the 2nd crack?I think mine cracked when I was jumping it .I landed hard on the right rear wheel.Shortly after I noticed the oil leaking .I was only getting maybe 2-3ft of air and wasn't even bottoming it out when I landed .I have seen 300ex's get big air and land hard time after time with no problems,so this kinda pisses me off.

 

my buddies lakota the chain came off twice and busted a piece about the size of a quarter out of the left side of the case.. both times. He just had it welded for $5 and no problems since.. but his chain hasnt fell off since either..

 

An harsh landing shouldnt have done it. What do you all have done to the engin of your 300ex? Most likly it is just fatigue or your engin's mount wasnt tight enough, and it fatigued a crack. I rode mine everyday all day for 4 straight years. I had Piston, port, valve job, and a bunch of other little things. I think it just vibarated to much and the mount might not have been tight enough?

 

The 300ex is factory stock except for a Cobra pipe and rear tires.It still has the original factory chain,(which did not cause the break).I removed the motor myself,the bolts were knuckle busting tight.I have checked the frame for cracks,none..anybody have a left case half(cheap)$112.00 from Honda plus all the gaskets and seals,ect..Have not been sucessfull with welding it.