Re: 1970 Honda CB450 K3 - Tentatively named "Grey Ghost" Build
After about a week slowly picking away at cleaning up the engine. I used a combination of a dilute Green Clean solution to rinse the engine surfaces, then using a nylon brush and a tooth brush (different things) I just scrubbed away. I'd also use a more powerful industrial strength citrus cleaner for the grimey parts. I then went over all surfaces with a Red scotch brite pad.
The biggest pains were getting inside the fins. Its not too difficult to get a brush into the crevices to about the same point that you can visually see the metal, the problem is getting all the dirty, oily foam out. Also, they are great places for dried spider nests that really get worked into the bristles of your brush if you happen on one. Make sure to the blast those suckers, along with all the other dirt out with compressed air before scrubbing.
The frame took far longer to get done then scrubbing the engine. This is because I chose to save money and take on the task of stripping it down to it's birthday suit myself. Why? Because I'm cheap and because I like doing things myself.
I started it by trying some aerosol aircraft stripper. Because I had to do this part in the garage or risk killing myself, my girlfriend, and my dog with the fumes, it was pretty damn cold in there. I do live in New Hampshire. I think this worked against the aircraft stripper, because it didn't do sh*t. Even if I wrapped the frame in a trash bag while having a heater aimed at it, the stripper barely took off the clear coat on this frame. When I did get past that with a scraper and took off the aquamarine color coat, the mysterious maroon primer/rust layer underneath just turned to an oily mess. I still don't know whether this was some oil or lead based primer, or just a liquefied layer of rust that developed underneath the top coat, but air craft stripper just makes it smudgey.
I tried out a wire wheel attachment to bite into the paint and then adding aircraft stripper. Didn't help much (it's still cold). I also tried a Quick-strip disc but that is a pain in the ass and I overheated my power drill. I also went at it with a DA sander and some purple 120 grit automotive grade paper. I went through an entire sheet of it with little results.
All in all, I found these methods were either too time consuming, tedious, or I'm just too damn impatient. This below pictures is after about 3 hours of trying the methods above. Some people might say that's good progress, but I wasn't convinced.
Finally, I wised up, and ate into the $100 cost-savings budget of doing this myself and bought an Needle Scaler from Harbor Freight for $30. Sweet Barbara, this thing is bee's knee's.
I finished the rest of the frame in about 3 hours. It turns paint into fine bits of confetti that just drop down underneath your work. No sand to clean up, no paint fumes, and no repetitive movements. I'm surprised I hadn't found a single post on the forum for using this. It also takes rust and other nasty bits of scale like nothing too. The trick is to just keep it moving, perpendicular to the work surface, and keep it oiled before and after use. Also, it sucks a lot of air, about 4 CFM at 90 PSI, so either have a big tank or expect the compressor to be running constantly. And, ear pro is a must. This sucker is loud. Its metal banging, scrapping, and slapping against metal.
It does leave an imperfect finish, it doesn't smooth it down like glass bead blasting, but it takes off paint in even the tights nooks and corners. I just hit the surfaces with the purple 3M paper and it smoothed it down quite nicely. Far, far, quicker than sanding the entire thing.
Once I was done scaling and sanding, and I used some Rust Converter on the bottom of the frame that had some rust spots that remained after sanding. All those dark runny looking stains are from the Rust Converter running while I had the frame upside down. Rinsed the beast down with alcohol and lint-free towels, masked it, and it was ready for paint.
