[Bouma]

<div class='quotetop'>QUOTE (Wyo_H1_Cat @ Feb 1 2010, 05:46 PM) <{POST_SNAPBACK}></div>

In my opinion the CPR8E and the CR6E are functionally equivalent. Yes the CPR8E is two heat ranges colder because it has the extended nose electrode. Because the CR6E does not have the extended nose, it has to be a hotter running plug but a colder heat range plug to keep it burning clean. Look at the plugs you can see the difference.

Heat range is a number that reflects how fast the plug can carry away heat from the spark plug and transfer the heat to the cylinder head. If the plug is too cold, it carries away heat too fast and the plug can foul, if the plug is too hot, then not enough heat is carried away and the plug will wear quicker. In NGK plugs Higher the Heat range value the faster the plug carries away heat and the colder the plug electrode will burn And the Lower the heat range value then the slower the plug carries away heat and the plug electrode burns hotter.

American made plug are the opposite in heat range numbering from Japanese made plugs. On NGK the higher the higher the heat range value then the colder the plug burns, in Champion plugs the higher the heat range value is then the plug burns hotter

I think you just had a bad plug to begin with, as for plugs the CR6E or the CPR8E are both recommended plugs for your machine. I've seen several machines all with the same engine, some with the poor quality champion plugs, some with CPR8E, some with CR6E from the factory, they install probably what they get the best deal upon when ordering. this is in 400's all the way up to 950 Thundercats.

There is a method to read the color change on the ground strap to adjust the heat range for what your engine requires. Engine mods, exhaust and intake mods may require a different heat range then recommended for a stock engine. Reading the ground strap is easy. Covered in the Jetting 101 thread in the ATV pinned section. The best selection of multiple heat ranges is available from Denso. You can get heat ranges from IU20, IU22, IU24 & IU28. They are also iridium plugs which in my opinion is the best out there. Iridium in my opinion also allows and engine to start easier and idle smoother then a non Iridium plug. I'm running the IU22's in both my Tcat and 650H1. There is really nothing magical about spark plugs. As long as the thread diameter, Thread pitch, Thread length is the same and heat range is correct to match your engine with or without modifications it will work.

Heat range once again is only a number that represents how fast heat is transferred from the plug electrode to the cylinder head. Plug design may require a different heat range, Such as a CPR6E is NOT functionally equivalent to a CR6E, the CPR6E would burn out too easily in your engine because it would not carry the heat away fast enough and the plug electrode would burn away.

YOU HAVE NOW WORRIES with EITHER the CPR8E or the CR6E, try a CR7EIX sometime, you might like it better or the same plug from Denso is the UI-22[/b]

WYO Thankyou!!

I am getting the hang of it now. Great post, I plan on getting a CR7EIX. I will say that my cold start problem is fixed. I ran it last night after it sat for 2 weeks in temps of 1 degree through 20 degrees. Started good. Thanks for all the help everyone!!!

 

[ibmeat]

I had the same starting issues with my 08 XTX 700 EFI, had it in to many times to count, would start 1 day and not the next! after 6 weeks of trouble shooting, trying everything from CDI boxes to Fuel rails, it turned out to be a flawed head gasket from the factory!!! a small tear was letting a small amount of anti-freeze in the cylinder. since replacing it it starts no matter how cold it gets.