Frame mounting.

[crackerjac]

I need some opinions on frame mounts. I'm using a Zongshen 250 (232) air cooled motor and a 05 Honda 450X frame for a trail bike build. I was wondering if it would be strong enough to have just the head stay mounted, the two front (red) engine mounts, and the rear lower (blue) mounts mounted to the frame but leave the top rear mount (green) unmounted?

Otherwise I will be doing what others have done and make a C - type bracket for the back mounts that attaches to the rear swingarm pivot bolt. It just wouldn't look as clean.