The chain guard (or chain case if you prefer) on the 1972 and 1973 model GT750 is plastic, and you often find that the mount points are damaged. Over time the two special ‘top hat’ washers typically go missing, and just using an ordinary flat washer compresses and then eventually fractures the plastic, making it a scrap item. As these original plastic guards are becoming hard to find, it makes sense to use the correct fittings, especially as they are still available from your friendly neighbourhood Suzuki dealer under part number 09169-06010. Locally here in Calgary, I deal with GW Cycle World which is a family owned business who have been very helpful to me over the years. Recommended.
The horn on these is the early louvred style, having a chrome plated cover which is held in place by five aluminium rivets. As is often the case, the horn I wanted to use was not actually working, but luckily they are fairly easy to repair. I’ll post more detail on my web site at this link, but basically so long as the coil is good you can usually bring these back to life by cleaning the contacts, and then by adjusting both the points gap and the distance that the solenoid (hammer) is pulled into the coil before it hits the anvil . The anvil is threaded in from the back of the horn, and moving this in or out will change the pitch of the horn, although admittedly the sweet spot is quite small. What you do not want is for the solenoid/hammer to be set so it can’t move to open the contacts, as that risks burning out the coil. The adjustment is the small cross head screw on the back, and I use an ohm meter to ensure I am starting with an open circuit before applying power and trying to make adjustments. On this one, I had the louvred cover re-chromed, reattached the cover using stainless steel screws, re-sleeved the wires and it is good to go !
Suzuki changed over to having an AMP connector block to join the front and rear main wire harness together sometime after the 1975 model year I think. This was a great improvement on the earlier style of connectors which had a tendency to overheat and melt the connector jacket, and then potentially short out under your fuel tank. Not an ideal situation ! The harness I planned to refurbish for this project was the later type, and as part of that process I had to get the AMP connector apart. The AMP connector is a bit fiddly in that to release the pins or sockets from the plastic holders for cleaning etc., you need to compress in the two retainer tangs located on each side of the pin or socket that lock it into the plastic holder. You can see one of these tangs in the photo to the right. A similar pin extractor as used on the 3.5 mm flat blade crimp fittings will work which can either be bought or made.
Next on the list is the switch gear !