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Discussion Starter · #1 ·
I have a question for you guys:dontknow: how many spark plug in the engine of the 109 I've only seen 2 where are the other 2
 

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There are only two cylinders and therefore only two plugs.

Why would you assume there would be more than 2?
 

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Discussion Starter · #7 ·
Thanks Bobby the reason I asked is when I went to the dealer I asked him for 4 plugs but he said there are only 2 so I replaced them then on the site everyone was talking about 4 plugs and wanted to know where the other 2 were and Lee told me they were 3 inches apart that the coil cap has 1 underneath it looked it up in the book and there it was went by what the dealer told me thanks
 

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Thanks Bobby the reason I asked is when I went to the dealer I asked him for 4 plugs but he said there are only 2 so I replaced them then on the site everyone was talking about 4 plugs and wanted to know where the other 2 were and Lee told me they were 3 inches apart that the coil cap has 1 underneath it looked it up in the book and there it was went by what the dealer told me thanks
The parts manager at my dealership told my buddy the same thing....only 2 plugs. The only way he got out of there with 4 was by telling the parts manager that he was buying 2 extra for next time! LOL :D
 

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Two in the center of the heads and two on the outside, under the chrome covers, one on the right front and one on the left rear. That makes 4 to me.
 

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WHAT BRAND OF PLUGS DO YOU RECOMMEND? I AM ALSO USING A POWER COMMANDE III, 2 INTO 1 SIDEBURNER, THUNDER TORNADO AIR INTAKES W/K&N FILTERS. THIS BIKE RUNS VERY WELL AND HAS NEVER HAD A HICKUP SINCE I PURCHASED IT. I DONT EVEN KNOW WHAT I HAVE IN IT NOW?
 

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I FORGOT TO MENTION I HAVE HAD THE BIKE DYNO AT OWENS HARLEY D.
107HP 110TQ, I BELEIVE THEY ARE THE STOCK PLUGS THAT CAME WITH THE BIKE.
 

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There are four spark plugs used on this engine, two for each head. The reason for two is one is for firing the charge for the power stroke and the other is used to lower emissions by firing on the exhaust stroke, but by having two per head the spark timing can be altered at times for more power using computer algorithms. Diesel trucks today use similar algorithms to quiet them, to produce more power, and reduce emissions. In other words, there are four, two use a plug wire similar to those used on the older cars, and two have each a coil on top of them with two wires attached.
 

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Oh, sorry, use the same style plug that came out of it. The engineers have developed the engine to take the double electrode spark plug and it runs better with that style plug. I have tried, not on this engine, using different spark plugs on other engines with this style plug, but have had them produce problems later. I'm sure someone will say they have changed to a different style and had no problem, and maybe they haven't had problems, but my experience has been different.
 

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Changed all "4" of mine at 22,491km and they looked great. Changed only do to mods and dyno tuning.
 
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