Friday, August 3, 2012

Not a bolt-on....

Whoever said a 1980 Ironhead Sportster engine would fit in a 1970-1978 frame has never tried it!  It will work the other way around ( a 1970-78 engine in a 1980 frame), but the 1980 and on engine has a deep sump, and the original crossmember needs to be cut out, along with the peg mounts (left side hits a large reinforcement area of the side case), and the crossover linkage tube (still shown in this photo) hits the rear of the left case.  Overall the 1980 engine is beefier.  I also had to remove some material from the swingarm pivot, the old swingarm is larger and also the swingarm pivot nut on the left side hits the side case.  last m od was to heat the lower rails and pound a flat into the right side where there is a large bulge in the right side case.   All in all the mods were worth it, rather than writing off this (much cooler) 1972 frame and trying to modify the garbage 1980 frame.

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