- Hi everyone! Happy to be here. Recently began the rebuild of my 71' cb350. I'm currently replacing the motor mount bolts and I have them all switched out but the rubber grommet between the washer and the engine is worn out on both the right and left side of the engine. Is there a place to buy replacements or can I get away with bolting the engine to the frame without them? The stainless steel bolt kit (from alloy bolts) didn't include replacements so I'm wondering if maybe they are not necessary or if the engine will vibrate against the frame too much without them. Thanks guys!