Yo cotton,
The z is an awesome bike, and moving up from the warrior you will be very happy....believe me I waited a long time to get my z at the right price but if you wait, and are constantly on it, you can get a great bike for a great price. Dont forget that the 03 models actually came out in the latter part of 2002 so the 03 bikes are actually going on being a solid 2 years old if not more. You shouldnt pay more than 3500 for a "good" shape bike....stock......and as far as mod's go I know alot of people have different opinions, but mine is that it does not raise the value of the bike at all. I would never want to buy a bike that has been all modded out, and for me that actually lowers the bike appeal. I actually found an 04 z 400 still under warranty on ebay, and got it for 3550.00. The bike had normal scratches from riding, but other than that it was in perfect shape. I've done more damage to it in the three weeks that I've owned it....
So realistically you should not pay more than that for an 03. The z is a great bike and I hope you can find one...yes the z's did have a weak frame in '03 but supposedly like the other guy said it's not a problem unless you are really killin the thing. Also I read another thead on here that for like 30 bucks you can get the frame reinforced by anyone who knows how to weld. But check it out, search for gussets?? i think....anyway if you get an 04 supposedly that was fixed. Just keep your eyes open and when you least expect it a great deal will come up... Just dont rush it....and the end of the season here come winter, im sure you will see alot more bikes on the market...that and beginning of next summer when everyone's got money and wants a new bike....
Lastly as far as the bolt patterns im not sure, but I did see one used z with 400ex front tires on it. Not sure if they modded it in anyway to do that, but it has been done. Good luck...

 

The Z is a great bike, fun to ride. just finished mine today cant wait to ride it tomorrow have to try out the new swingarm
beat my buddys YFZ 450 last week with it and made him mad at me so he took it in and gained 7 more horse in it
cant wait to race again. keep the rubber side down and your feet in the air[img]i/expressions/face-icon-small-smile.gif[/img]

 

I also had a Warrior before I got my DVX(same as a Z). It is a huge improvement over the Warrior, the only thing I had to get used to was less ground clearance(Warrior had 22 inch tires). Mine is all stock right now but i'm starting to MX a little and have noticed that the paint on my frame is cracking around the upper shock mounts. I think that's mostly because I came up short on a pretty big double. I landed pretty hard and bent my stock handle bars. I checked the frame after that and noticed my paint was cracked and beginning to rust.

 

Hey mucky how bad did you beat your buddys yfz-450?

 

I'm a little confused. You say you want to use your Honda/Yamaha wheels? The Z bolt pattern is the same as the Honda's. Yamahas have their own. So if you're asking if you can use your Warrior wheels the answer is no. Sorry. As far as the Z400. It's just a great bike. I'm a die hard Honda guy, but I love it. My girlfriend (Lolli2) got one, and now it's all I want to ride!

 

mucky your bike only made 44hp?? i watched a stock bore Z with the stock carb make 44hp.

 

its has 44hp at the wheels thats what the dyno showed. I can feel the difference
and besides its better than what stock hp is. I was told stock only has 29/30hp
I beat my buddys yfz450 by about 15 feet is was a nice feeling and
besides im a little over weight and for every 12lbs over you lose 1hp

 

oh i thought it would make more than that.

 

I dont know if dynos are 100% right but im happy with it
it scares the heck out of me every time I ride it
what a difference it made

 

what gearing are you running to get 82mph