bob i don't know the metric size but a small 1/4 inch bolt and nut should take care of that, my set is different now but i know a 1/4 bolt will fit the hole.
its a good thing you caught this that helps support the carb and intake.if the carb flops up and down it won't be long until it causes the rubber to let loose on the intake and then leak.
hope that helps pud _________________ 2006 sunl 150b
Dr. pulley 10 gram sliders, 1500 torque spring,39 tooth sprocket,2000lb winch, red neck uni filter, 125 main jet at 1,450 elevation, drilled out exhaust,ngk iridium plug,performance intake
trying a set of 10gram rollers now