I have two CBR1000 engines and one (almost) complete '88 bike. One engine is what I believe to be an early one with the water exits on the rear of the head and a later one with the exits on the side. These both came together so there may have been some cross parts swapping. What I can not figure is why the plug lead order is 1324 on the later engine. The earlier engine doesn't have the leads attached but from the length they go 1423. For a 1243 firing order the pistons of 1 and 4 are up when 2 and 3 are down so 1 and 4 should be on the same coil and 2 and 3 on the other. The only way this can work is if the pick-ups have some weird rotor arrangement with lots of wasted sparks. Is it simply the previous owner has got them wrong? 1 and 2 will swap without length issues. Any enlightenment gratefully received. Thanks.

 

1-4-2-3 with wasted spark IIRC.

 

Thanks.