01-06-14, 10:59 AM
Because the bike has two coils. One coil fires 1&4, and the other fires 2&3. It's called a wasted spark system, and what happens is that when cylinder 1 gets a spark, cylinder 4 does too, but on the exhaust stroke. Same goes for 2&3, hence the wasted spark.
So, if you swap the plug caps from 1 to 4, and 2 to 3 it won't make any difference to the running of the bike. However, if you've got a bad lead or cap etc this is a good way of trying to pinpoint the problem
In my case when I swapped 2&3 I half expected 3 to stop firing because it was using the lead and cap from number 2. Instead number 2 stopped firing hence ruling out the lead and cap
So, if you swap the plug caps from 1 to 4, and 2 to 3 it won't make any difference to the running of the bike. However, if you've got a bad lead or cap etc this is a good way of trying to pinpoint the problem
In my case when I swapped 2&3 I half expected 3 to stop firing because it was using the lead and cap from number 2. Instead number 2 stopped firing hence ruling out the lead and cap