Hi everyone. I'm sure I'm not the only one running some ratty pipes. I tried something this week that seemed a little crazy at first, but now that it's done, I think it could be helpful (maybe).
HM300s are really expensive, and the replacement ones have a modern govt warning stamped on them. I'm not sure I want new ones, and definitely can't justify NOS or even what people seem to be asking for super clean used ones (assuming you can find them).
Welding would have been one way to seal up the holes, but man, that metal is thin, and pretty easy to burn.. so I came up with another tack.
Once i removed all the baffles and got the pipes off, it was easy to see how such a low mile bike could rust pipes out so badly. The weep holes were completely blocked by road grime.. probably happened pretty early on. Water just stayed in the pipes.. and we know what happens then.
I first took a dremel and cutting bit and just ground away any holes till it stopped spewing red dust. In one case, that took off an awful lot of material. .. now what?
I took aluminum cans and cut shapes to fit in or over holes, or from behind where possible. Used a rivet here and there to secure the patches. Then I took fiberglas strips coated in JB weld and laid them over the patches, smoothing down with a plastic scraper.
Then sanded the jb weld as smooth as I could.
3 out of 4 baffles were rough.. after drilling and retapping the retaining bolt holes, the bases were pretty rotted out, a 2 part epoxy putty did a great job of filling those holes and was easy to manage. Painted them up, repacked the fiberglass with insulation and made new exit gaskets using an old 10-speed inner tube. Worked awesome.
After riding it for week, all fixes held, and i was finally able to really tune the thing, with all exhaust pressures finally being even.
THEN, I took 'em all back off to attempt some cosmetic work. All I can say is, rustoleum's metallic paint is pretty amazing.
I know this is pretty ghetto, but it works, sounds great, and looks a far cry better than it did before i started.
Feel free to give me crap about it, or explain why this was dumb... or better yet, tell me you have some pristine hm300s in your garage you want to give me for next to nothing.
