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General Category >> Rubber Side Down! >> Dual Fire Ignition?
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Message started by Mr. Hyde on 09/28/08 at 08:53:51

Title: Dual Fire Ignition?
Post by Mr. Hyde on 09/28/08 at 08:53:51

I just read that the L650/S40 has a dual fire ignition system. I thought you had to have 2 plugs for a dual fire ignition. Can anyone clarify for me. Thanks

Title: Re: Dual Fire Ignition?
Post by verslagen1 on 09/28/08 at 09:17:51

It maybe a misnomer, the savage fires every revolution because the ignition keys off of the crank rather than the cam.

Title: Re: Dual Fire Ignition?
Post by serowbot on 09/28/08 at 10:55:47

I believe it's called a "wasted spark" ignition,...only every other spark is actually is used for combustion.

Title: Re: Dual Fire Ignition?
Post by SuziQ on 09/29/08 at 23:25:46

The four strokes in a cycle; intake, compression, power and exhaust require 720 degrees of crankshaft rotation (2 revolutions) to complete. The single cylinder having no other cylinders to share ignition with fires the spark plug at the top of the compression stroke and then again after a full revolution at the top of the exhaust stroke where there is no combustion and the spark is wasted in this sequence but it fires easily as their is no compression to fire against. Twin cylinders sharing a single two tower ignition coil also fire a wasted spark as both plugs fire simultaneously, again one on it's compression stroke and the other on it's exhaust stroke. Single cylinder engines are more difficult to start, the engine crankshaft must go through 2 complete revolutions for a firing event to occur and are often designed with a timed decompression system where a lever opens an exhaust valve while the starter motor is running, relieving compression against the starter motor until ingnition is sequenced.

Title: Re: Dual Fire Ignition?
Post by EssForty on 09/30/08 at 02:17:26

A single fire ignition only fires a spark during combustion. A dual-fire ignition fires a spark during combustion and a waste spark during exhaust.

Dual fire is simple and cheap whereas single fire costs more but gives smoother operation.