So i bought the 400, it needs rings and a swingarm bolt. Out of the pile of parts I got that are the things I know I need. Well I wanna ask you guys who have them some questions. I have a white bros full exhaust and the rest of the big 3. My question is what would you do to the motor to have a nice reliable trail rig that will give a z400 fits. What should I replace or modify while it is in pieces. I have 2 other atvs so it doesn't matter when it gets done.

put a ims 440 kit an get the head ported an polish mine get as!!! forgot also got a new carb been a few years it will be a rocket

DO NOT GET A 440 kit!! Stick with a 416 or 426. They are more reliable and cause less vibrations throughout the bike. Do some sort of web cam with new rockers and valve springs and some port work. Stick with an 11:1 piston so you can keep it on pump gas and you will have a nice machine.

416 kit, carb job, and call it good. The 440 isn't a bad kit, but are known to not be nearly as reliable as the 416. The 426 I'm not too familiar with, but my 416 ripped.

A bigger cam, 450R carb, 10 or 11:1 piston, plus the exhaust and filter it already has would be a great combo. That should be enough for a piped Z400, but if you think you'll need more then the 426 kit should be plenty.

Don't get a 440! It's not that they're unreliable, but they kinda are and get way too hot, too soon. If you want a trail quad, the 440 is not the way to go. I have a 426 on mine, and love it. A good cam will open it up real well. By the way, there's a kit on ebay (have to look for the link) for a bolt and bushings real cheap.

Makes me wanna buy another 400ex! So much cheaper to build compared to the xx.

That all depends on what kind of parts you buy.

Very true but parts for the 400ex are a dime a dozen which means you can usually find deals on parts. The XX parts are few and far between when it comes to deals.

True true, parts availability is alot better for the 400ex and there are lots of things that are interchangable with other honda bikes.