I’m doing a frame up build of a 2003 400ex. It has a rebuilt bottom end and no top end…I’m also trying to get my hands on a 2005 for parts that has a complete engine.

That being said, I have money to spend and time to do the work. This is my first quad build, taking a break from cars so I have a decent mechanical background and will be doing everything myself. The question is, what do I do?

I’m not racing, this will be trail ridden. I’m thinking big bore kit, 440 maybe seeing as I’m looking more for torque that top end (assuming the larger bores = torque like in other applications?)

So what’s the best path to take? I’m hoping to get the 05 to have reverse, but didn’t miss that when I had a banshee. 440? What pipe and muffler, will the stock header do with an aftermarket muffler? Uni-filter or those air box delete kits?

Spend my money!