Well, here it is: I made the pattern for the baseplate and built and installed one on a 1977 750F for the example. I think the wires are a bit too long, so the next ones will be a little shorter.
It's going to be about $40 for a unit (plus shipping). Each one comes as a 4-position holder, with 3 positions used and a spare 15 Amp fuse in the unused position. The fuses are 15, 7.5 and 5 amp: if you have a CB550F I think the stock 5 amp one is 2.5 amp, but no matter, it will work fine. It plugs and bolts straight into the old fuseholder's spot: just unhook your battery first to avoid electrical sparks while changing this fuseblock.
It sure brightened up the lights on this 750! The lamps were seeing about 10.6 volts before I changed out the grungy old fuseholder, now they see 12.0 volts at the taillight bulb.
Below is a picture of the stock 750F, the fuseholder (and an old one) and the final installed unit. If you need higher-resolution pictures, e-mail me: mgparis@concentric.net (which is also my Paypal).
I should have some assembled by next week. Like the Ignitions, each sale here will generate $1 back to SOHC4. These will also appear on my website as soon as we get it operational.
