A buddy of mine (Chuck) is reconditioning a 1974 Suzuki GT750 (“water buffalo”) and wanted to repaint the crankcase. The top half was originally silver, but he wasn’t sure the best way to go about actually painting it. We were discussing the situation one day and I suggested we powder coat it. Though I had never powder coated anything this large and complex, coincidentally I had just recently bought a pound of silver powder with just such a potential project in mind (though I didn’t know this would come along at the time).
Chuck bead-blasted, thoroughly cleaned, masked and then bolted the cases together before bringing them over. We had already checked the overall dimensions before he arrived so we were confident the unit would fit into the oven. We simply had to determine the process to allow for the application of powder on all sides of the assembled cases while protecting the powder during handling and baking.
After some consideration we decided to use 6mm screws inserted into the bottom of the assembly, which was relatively flat. These screws acted as stand-offs and did double duty, they sealed a number of holes that would have had to be plugged as well as kept the cases elevated to protect the applied powder before and during baking.
Chuck came up with the idea of using long wooden dowels as handles, inserted through the motor mounts, which worked out well. This allowed us to stand the cases up on end, powder coat the bottom then using the dowels, gently lay the unit over onto the screws to complete the powder application process. We used these same dowels to maneuver the coated cases into the oven, which was the trickiest part of the whole project, due to the weight and bulk of the cases.
We are quite pleased with the result, which can be seen in one of the photos.
I’m laying down the powder…
Done baking, now cooling down, just about ready to come out of the oven…
The finished unit. It’s still in a cool-down phase here as it was baked at 400 degrees (F) for about 25 minutes so the unit took a while to cool down. We removed the heat-resistant masking tape as soon as we could. If you look carefully, you can see all the 6mm screws Chuck used to seal the various threaded openings in the block.
This project turned out great. Surely powder coating was the most durable coating we could have applied. On to rebuilding the motor. Many thanks Kelly.
Unfortunately, the integrity and strength of the Aluminum parts have now been compromised because of the heat they were exposed to. Hopefully it will not become an issue but for other parts like aluminum wheels which are also coated with high heat is not a great idea since their strength and integrity is so critical. Powder can be done at lower heat but obviously requires longer times in the oven but the strength of the aluminum will not be compromised.