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About the waste spark setup - Honda CX500, GL500, CX650, GL650

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The Honda CX and GL bikes - both CDI and TI setups - have a waste spark system. This means that the spark plugs fire once per revolution of the crankshaft, or twice per 4-stroke cycle.

Both CDI and TI setups get their timing signals from the crankshaft, not the camshaft. The crankshaft rotates twice per 4-cylinder cycle (intake, compression, combustion, exhaust), so if the bike gets it's timing signal from the crankshaft it will fire on both the compression and exhaust stroke. The camshaft spins once per 4-cylinder cycle, so vehicles which get their timing from the camshaft can discern between the compression and exhaust stroke and fire on only one of those if the designers wish.