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Discussion Starter #1
Does any one know what plugs for Arctic Cats are hotter or colder? Is there a chart? You know What plug number is colder than the other? I'm trying to tune my engine with my Pyro 2000 and need to try different (colder) pluges to bring douwn my exhaust temps.
 

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NGK BR8ES is hotter than a BR9ES, but how did you determine that you need a cooler pipe temp? It's a common policy to intesionally retain heat in pipes, i.e. ceramic coatings, heat shields attached to the pipe for heat retension. shane
 

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I melted my piston. So I assume it got over 1250 degrees near my exhaust port. I have rebuilt the top end and installed temp sensors 100 mm from the piston skirt and I now need to tune it rich enough as to not get the temp so high that it will melt the piston. But also still have good performance. I have an EFI and I installed a manual fuel pressure regulator on it so I can richen or lean out the fuel mixture, a higher fuel pressure to richen and a lower fuel pressure to lean it out. I wanted to get cooler plugs so it would run cooler so I could lean it out a bit more for the performance. By the way the temp got high because I installed a D&D chip and twin pipes. It ran great untill I opened it up on the lake for an extended run. Then it melted. With the Pyro 2000 I can watch the temp and avoid that unplesent experience.
 

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You want to tune the EFI fuel mixture not change the plug heat range, your pipe manuf. should be able to get you close to what it should be set at. Never in all my days of souping up sleds did I ever change the heat range of the stock plugs. More exhaust leaves the engine due to the twin pipes so you need more fuel and air to compensate it. Also I hope you dialed in your clutch after your engine mods because after you make the engine go faster the clutch must match the power band. shane
 

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Discussion Starter #5
I did have the D&D chip in there and I put in Boysen Racing reeds plus the manual fuel pressure regulator. I currently have that set to 40 PSI to start. After a few runs this weekend I will Dial it in.
I did Put the Heelclicker HXC roller kit on the secondary and changed the weights on the primary it seems to be fine but I lost about 10 mph off my top speed. Whats up with that? I will know allot more after this weekend as far as how my mods pan out on the trail.
 

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I was going through this last night myself. Of what I found is:

NGK is one of the only plug makers that the higher number, the colder the plug.

The rest, the higher the number the hotter the plug.



Chris
 

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Shane, you never dropped a heat range on your plugs, even with a modded sled? Bly, Shane is right you need to get your air/fuel mixture close before you mess with the plugs. Go to the ngk website. they have more info than you will ever need on plugs and heat ranges. As for losing 10 mph, sounds like its miss clutched. Give d&d a call, They will probably have the exact kit to match your mods. KEEP IT PINNED
 
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