Step Inside - Let's Talk Spark Plug Gap

[SaberKitty]

Just removed the original factory installed spark plugs on my '08 M8 (1100 miles) and checking the gap, they were about 0.025-0.026".

Opening up the box of BR9EYAs, found the new plugs to be gapped the same as the ones I just removed. Checking the service manual, Arctic Cat recommends the same 0.028-0.031" of gap on the plugs all the way from 370-cc up to the 1000-cc.

With the only mod to the engine being an aftermarket can, and running 87 octane fuel, what gap should I set the new plugs, on the small or big end of AC's recommendation?

 

[Green Cat]

This is important! If you get the gap wrong, your M8 will bog and trench really bad
Since your are stock, just shoot for the middle spec, 0.029" and call it a day. You won't be able to tell 0.001" anyway, and you will probably have that for a margin of error when you set the gap.

Too small a gap (it has to be really small) will make for a small spark. Too large of a gap creates excessively high secondary coil resistance in your ignition, since a higher voltage is required to bridge the larger gap.

Just shoot for the center and you will be doing all you can