im messing round with my t100c engine . ive got some pistons which are boxed as e7603 (1970 7.5 to 1 compression t100c pistons) but are stamped e7587.i have yet to find a listing for e7587 in any parts books .

these pistons have thermal slots which in effect direct the heat to the small end boss area and reduces heat on the piston skirts / walls . this being the case should these pistons be fitted with less bore clearance , ie 4 thou instead of 5 thou ?

these piston designs are supposed to help with oil consumption, fuel economy and emissions and i am guessing triumph was trying to get by ever increasing emission regulations in the states which was their main market . however around the same time norton has designed the commando with similar thermal slotted pistons and a lot of pistons broke in two when used hard , so its possible that triumph decided to shelf the design then a few years later decided to use up the stock or use as low compression options . things had got tight money wise by then .

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