I have an 03 400 and rode with my buddies who just bought a yfz and trx 450's...it wasn't a pretty picture....i went ahead and got a motoworks full exhaust, and a K&N, neglected to get a Dynojet kit with it but i'll be doing that this coming friday.... But anyway, I'm planning on getting the 440 Big Bore kit that Magic Racing offers, its 699.95, and appears to come with the jug, piston and gaskets....has anyone used this kit? think i'd be wasting my money? any input would be great....thanks

 

OR SHOULD I JUST HANG IT UP AND GO GET AN LT-R 450?

 

on ebay they got a 440 kit for 583.00 its a athena kit with jug piston and gaskets still dont think ud be smokin 450s but maybe ud need to get better cams to take full power outa ur 440 kit though

 

Dosen't the Z need cams, ignition, and a bigger carb to get the most out of a big bore kit? That's gonna be tough to do for less than a grand.

 

when i did my 440 the first time it cost around $2K for it, it included boring, resealed cylinder, 41mm carb, port and polish, cams ,timing chain and guides. then it cost another $350 for the new valves and springs in the head.,I already had the exhaust on it ,so it can and does get expensive to do a 440. you dont have to go for the extreme, get the 440 kit and rejet and when you have more money and time then do the head ( valves and springs, porting, cams)and a good cdi box will help even the stock motor. and if it seems like to much trouble then sell it and get the 450

 

yea i like that plan mucky, thanx

 

i spent under 1k on a 440 big bore kit from weisco in my 03 Z and its by far worth the money, the bottom end is an trememdous difference but top end really doesnt change besides the throttle response..

 

The setup I have puts it on a stock 450 pretty bad in a drag race. I raced a lightly modded 06-07 YFZ (Exhaust, jetted, air lid removed) and we we side by side with me inching away on topend. Now that I have put a 450r carb on it, the story would be different. The carb made a huge difference. Also, my buddy has a stock 07 450r and I put about 6-7 bike lengths on him. The funny thing is, he would get me off the line every time. Once I was in third, I was pulling away. So he asked to ride my bike afterwards and he didn't wanna give it back! He said it was a beast for a 400. That was without the carb. You can mod your bike in steps. The z400 has lots of potential, and it has reverse. The setup I have is able to be lugged down low, and has plety of topend. If you want everything in my combo, i'll be glad to give it to you. By the way, its still a stock bore. Just wait till I do the 440.....

 

I would love to know what kind of setup u have on ur z.

 

450r 42mm carb, drz400 base gasket (more compression), DID timing chain, yoshimura carbon fiber exhaust, web cams, I ported the head, drz400 valve springs, trailtech light weight flywheel, 13t front sprocket, non o-ring chain, open air box, adjustable procom rev box, easy pull clutch lever (awsome for trail riding) lightweight rear waved brake rotor, aluminum handle bars, AND SOME STICKY GRIPS so I can hang on. Its really not any special combo, but it works. web cams are 234/244 @ .050. The grind numbers are 288 for intake, 536 for exhaust. Yes the DRZ400 valve springs work fine and fit the factory z400 retainers. They are cheaper than aftermarket springs and retainers. I have a pro flow type kit for the air box with a bigger filter. The carb boot opened up a bit. I clearanced under the seat for more airflow. The seat sits really close to the top of the airbox and I rode the bike one time without the seat and it felt stronger. So I partially cut out some of the ribs on the bottom of the seat. Seems to have helped. Its the details that count.