I just put a dg full system on my o7 trx 450er and I have not jetted it yet. Before the system was on it was probably running rich. the reason I haven't jetted it because it seems to start better and idle better. And the quad seem to sound really good through all gears. The only problem is I felt it lag a little while giving it quite a bite of throttle at mid-high rpm I wasn't sure if it was because it's running lean or because it was a little flooded my friend was driving it a minute earlier and stalled it twice.I don't blame him though he's not uses riding such a power full machine like a trx because he owns a 06 yfz just kidding. Thank you to anyone who can give me some advice. I can also add more information if it will help you answer my question.

 

Welcome to the forums
If the exhaust is the only mod the quad has been done you might get by with just adjusting the carb , i would clean the air filter first then ride it 10 or so mile's and then pull the spark plug and check the color of the extrode ; white/grey color you're running lean , black/soot color you're running rich , a light tan/brown color is what you want .

williebee.......

 

Forget that 10 miles, you could frag that engine in 10 miles. The 450s usually are a touch lean from the dealer, I would pull th plug now and take a look. If you haven't done any intake mods you can probably just go up a couple main jet and one pilot, adjust the fuel screw and call it a day. The other thing is contact DG and get their recommendations.

 

It does have a k+n air filter if that makes a difference and I did clean it before putting the system on the quad. And I have a dyno jet kit for it so I guess I should adjust it I don't want to have any problems with the quad because I was too lazy to jet it.