I just installed a AAEN top end pipe on my 98 400 sport. I also added K&n fillter and dial-a-jet. I adjusted the daj according to the instructions and after running it full open for 3/4 of a mile then letting it coast to a stop and checked the plug. The plug was a gold to tan color. I then rode it for about an hour easy with my son and the fan kept comming on. Before I added the extras the only time the fan ever came on was after running hard at the dunes for several hours. Do I need to worry about it running hotter now, or is it normal. I don't want to burn up the piston or cause any other internal damage.

 

One of the main reasons you get added power with a correct pipe is because it scavenges exhaust better and actually bounces a wave back at the exhaust opening a split second before the piston covers it up, pushing some of the unburnt gases back into the cylinder. More air and fuel equals more power which equals more engine temperature or the tendency to build more heat. Not to worry,though. These machines have a good cooling system and it does not hurt it if the fan comes on. You have a temp light if it does get too hot. My wife's scrammy runs the fan quite a bit even when just trail riding or alot at the dunes. Proper jetting is the key to keeping it in control and preventing serious problems. Bubba

 

It sounds like it might be running a bit on the lean side. bump jet sizes a few and see if that helps at all. i personally feel that the spark plug should be a light brown to brown. rich is better then lean

later

 

General riding is covered more by the needle than the main jet. I would adjust the needle to a notch or 2 richer. If it blubbers then you know it's too rich. I run my xplorer slightly rich to be on the safe side.

Waylan

 

Thanks guys, I'll turn the jet a little richer and see how it goes. There is definately a big difference with the pipe, it'll pull the front tires off the ground now hammering it at half throttle, but it seems to have lost a little bottom end, but still has enough. I'll let you know how it goes. Thanks again!