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I was just looking through a snowmobile parts catalog and saw sparkplug indexing washers for sale. does it make much difference having the plugs facing the intake port, or is this another "boost bottle" type improvement? by the way there is a boost bottle in here for sleds lol

i can tell you the boost bottle actually helps with sleds; they don't have a x-over tube stock, and it's easy to smoke a belt on the trails, but it helps keep that from happening. i have heard of indexing years back, but it's not one of those all-popular things. i don't know if facing the plugs tward the intakes is right, but on larger bores and four strokes, there is a higher velocity across the plug which is evident on a plug that has been left in long enough to see the wear. it seems like shiming the plug to get the proper index would be a littl unreliable, and could cause your plug to come loose, but i have been modifying the combustion chambers on different engines to combat which has shown increase in power and efficiency, but that is a story for another day.

 

long story short, i wouuldn't recomend it, but you would probably be better off looking into side gapping instead. :thumbsup:

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I was just looking through a snowmobile parts catalog and saw sparkplug indexing washers for sale. does it make much difference having the plugs facing the intake port, or is this another "boost bottle" type improvement? by the way there is a boost bottle in here for sleds lol

 

 

 

In extremely high tune engine ( like karts) where absolutely everything counts, it has shown some gains, but i really doubt you will see any substantial gains from it in a multi cylinder engine. The theory is to aim the ground strap at the intake to shield the center electrode from "spark snuff" but really could be easily over come by a better ignition system. Because of the most modern combustion head domes, much flow at the point of combustion is very symmetric which would not matter too much with plug indexing.

 

 

 

All in all, we have not done enough testing with this to know for sure but tend to lean towards "not applicable" to banshee or similar engines. Many sled motors utilize similar designed heads so I would tend to think they would not benefit from the idea either.

 

 

Brandon

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i can tell you the boost bottle actually helps with sleds; they don't have a x-over tube stock, and it's easy to smoke a belt on the trails, but it helps keep that from happening. i have heard of indexing years back, but it's not one of those all-popular things. i don't know if facing the plugs tward the intakes is right, but on larger bores and four strokes, there is a higher velocity across the plug which is evident on a plug that has been left in long enough to see the wear. it seems like shiming the plug to get the proper index would be a littl unreliable, and could cause your plug to come loose, but i have been modifying the combustion chambers on different engines to combat which has shown increase in power and efficiency, but that is a story for another day.

 

long story short, i wouuldn't recomend it, but you would probably be better off looking into side gapping instead. :thumbsup:

Any facts on side gapping? I have read about it but not actually heard any hard facts from banshee owners.

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i can tell you the boost bottle actually helps with sleds; they don't have a x-over tube stock, and it's easy to smoke a belt on the trails, but it helps keep that from happening.

 

I guess i'm confused by this... How does a boost bottle/ x-over tube help keep a belt from breaking on the trails?

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The first and most important reasoning of indexing sparkplugs is to prevent the ground strap from contacting the dome of the piston. Second, if there is clearance 360 degrees, you should oreientate the groundstrap 180 degrees from the intake charge. This is so that the intake charge has the least amount of resistance to get to the electrode/groundstrap. Personally, I think in a banshee engine, the groundstrap should face forward. My reasoning is that when the main pressure wave of fuel/air enters the cylinder through the transfers, it is being directed up and rearwards to promote better filling of the cylinder while pushing the exhaust gases out. When the charge wraps around the cylinder/head deck and starts to travel forward, it has a 100% unrestricted path to the electrode... Evan

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smooths out the power hit?

bingo. with a boost bottle, you can give it just a little, and the power wont snap harder than the clutch can grab the belt and keep you from smokin a spot in the belt, which makes riddin jerky. proper clutching helps too. the shared chamber introduces the x-over feature, thus increasing power. they also don't weigh shit to a sled motor, so the intakes aren't at risk, unless you get one that's not spaced right, but you'd be cussin at it on install.

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