[Fr. Frank]

For the bolt, after extracting the broken-off piece, take it and the head and go to any Japanese outboard dealer, and ask a mechanic to look in their "junk box" for a used bolt of the same size. Most of 'em will give it to you for free.

For the carburetors, I do a "poor man's carb cleaning". I remove and disassemble the major components, and then soak jets in Quicksilver PowerTune. I also spray out the fuel and air passages with the same product. I replace the float needle (and seat if appropriate), and the blow out the small air passages with starting fluid (ether).

I then reassemble the carbs, re-install them, and start the motor with the cover off and air horn off, with the boat in the water (or in a barrel/tank, but NOT on the hose, you need the backpressure)

While running the motor, and tied securely to the dock, I put the motor in gear and increase the rpms to about 1500 - 2000 rpms. While running in gear, I spray PowerTune down the throat of each carb until the motor bogs considerably, but not enough to stall the motor completely. I will use a complete can of PowerTune through this process. The motor will smoke - A LOT!!.

After this I will take the boat out and run it at WFO for 8-10 minutes. Voila, you're done. BTW, don't do this last if you're over-propped. My last carbed motor was a big-block 150 Merc, (XR6 block 2.5 liter instead of standard 150 2.0 liter) and had a listed max RPM of 5500 - 5950 rpms, and was propped so I could run it at 6100 WFO trimmed out, and I did, frequently

If you're not comfortable taking the carbs apart without a carb kit, then by all means get the kit before you start.