HI, I have rebuilt many sets of SOHC 750 carbs and know how to set the float level. A friend asked me to rebuild his 1980 CB750 Custom carbs and I thought ,"It can't be that much different". The floats are plastic and do not seem to have any float level adjustment. Are they nonadjustable? The air shutoff diapharms look OK but should they be replaced anyway? Thanks Much Dan