I have been actively trying to get my 2000 SC400 4x4 tuned up now for the past week. I wanted to know if anyone has any suggestions or comments, any help would be greatly appreciated.

I bought performance parts from Hot Seat Performance, which included; a pipe, silencer, Hypershift Clutch Kit, K/N filter charger. I've just installed a 25 pilot jet and this cleaned up the low end (the 35 stock PJ was way rich in the low end). I'm running a 250 on the main jet with the clip in postion 2 on the needle. My typically operates at 900-1500 ft elevation and 70-85 degrees.

Does anyone know if the 25 PJ puts me at risk of ruing my machine? I've heard mixed reviews up to this point, some have told me to go with a 30 PJ and other have said the 25 should work fine.

Although my 1/4 throttle to wide open throttle is awesome now, my off idle to 1/4 throttle is still choppy. I tried adjusting the air flow some today, but I ran out of time. Does anyone have any suggestions? Would a different needle help at all? Is there anything I can do to be sure that my engine isn't going to over heat to the point that my piston siezes up?

I'm willing to purchase whatever I have to, to ensure that my machine doesn't blow up! I've heard of a device that measures the exhaust gas temp, would something like this be useful in tuning my ATV?

Again, any info or suggestions would be greatly appreciated, thanks in advance.

 

Keep an eye on the spark plug and how the engine runs. Let the engine tell you what IT WANTS, it's smarter than we are in that area. I found that keeping a small notebook for the quad helps me keep track of changes, and make better tuning choices. Also you don't have to rely on memory for all of your settings.
If you don't want to mount a pyrometer (Exhaust temp gauge) on the quad, you can get an infrared thermometer from Graingers( www.grainger.com )or other industrial supplyhouse for about $100 to $200 depending upon bell & whistles. They come in handy for other applications, engine temp, looking for hot spots in the radiator,checking oven temp for the wife, etc. once you get one you'll find a hundred uses for it...