another perfectly good motorcycle ruined.......

Friday, 24 December 2010


grant asked how the breather worked on the sporty so i will try my best to explain, the sportsters build up pressure in the rockerboxers so have to vent to atmosphere to prevent the gaskets giving up the ghost, on a standard sporty they vent through the carb mounting bolts back into the massive 'egg' shaped air filter assembly, i really don't like this as it hides the engine which, let's face it, really is a nice looking mill, so, the standard mounting bolts were counter drilled 10mm metric and a groove machined around them, [photo 1], 20mm aluminium scrap from my favourite scrappy's and a cardboard template and compass to determine the shape of the combined carb mounting/breather plate, working out the mikuni mounting flange pcd was a nightmare, dangerous said it couldn't be done, i had a sleepless night working it out, the mounting plate was then cross drilled at 45 degrees  and the outside of the mounting plate tapped 4mm and blanked off with a grub screw, [photo 2], the cross drilling vent's back into the bellmouth so you don't get any oil blowing back all over the engine as it's ingested back into the motor, not the best thing on a performance level as you need a neat petrol/air mix for optimum performance but it stops you ruining your beige golfing slacks with oil stains, [photo 3[, hope this explains what's going on here, yeah, i know it's sad but these things matter to me.....

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