Well i have bought alot from both Aaen and HPD i had a 97 Sport 400 that i did all Aaen except for the pipe! HPD has the best pipes I think! If you are looking a big bore kit Aaen BB kit is more CC"s than HPD. HPD is a 420 Kit and Aaens is a ture 440 kit. My 97 sport that Aaens did the 440 kit on i sent to HPD to have there port work done on it BECAUSE HPD does alittle more radical port job than Aaens, so but i told HPD to send me a new piston and there largest one was smaller than Aaens stock Big Bore piston so for your riding i dont think you need a Big Bore kit unless you just want to be the king of the hill. For your riding i would have HPD do it up for for Trail Riding. Just remember the more high performance you go the more problems you will have with it in the future! Now Aaens kits are going to be more dependable due to them being less porting but they will all wake up that 400 and make a BIG difference on it. For your Ritter Racing i dont know anything about them! Good luck with your bike. Let me just say that the Motor i had a 440 BIg Bore kit from Aaens and then port by HPD was rode very hard and ALOT, I never had any probelems out of that motor for a 1-1/2 years Great motor and then i just put new piston and rings in it and it was running great when i sold it last year!

 

If going from A to B the fastest is your goal, then stick with the smaller bores. If you want more torque for sand riding and such, go big bore. I personally wont do it again unless I run out of regular bores. The big bores require more piston clearance and they make more "rattle" than regular bores. I didnt really see a gain to speak of, just was able to say I had a big bore. You fill the top end better on a smaller bore than a big bore given the same primary crankcase volume. Bubba

 

Rick Ritter is good people. He is helping me build my 2000 Scrambler 400 4x4 in stages. He's listened to what I want and made (IMO) great recommendation based on what I want! Rick's service is second to none. Rick has his own parts and is a HPD distributor.

I went with a HPD trail pipe, stock muffler, clutch kit (minus helix), air box mods w/ new filter, and re-jetted the carb. $340 and it got my Scrambler moving. I'm going to do steering and braking mods next and finish my suspension upgrades. I'll send my topend to Rick at the end of the season to bore, port, and shave the head. I'll also go w/ a wiesco piston kit and girdling kit.

 

they're some good proven big bore kit for the 2 stroke 400,as far to tell the best,i really don't known cauze a big bore is a major task for an engines and setup,i didn't heard about them too much tough...
it still an expensive mod to make,the big gains when going bigger is TORQUE and throttle response,the powerband is also wider,but on the long run til top end,it will be hard to get a decent,usable power.
if you're looking for more power,you can upgrades the whole engine better
and it will outrun the big bore kit in the long terms.
for a 2 stroke before going bigger they're some really mods to make
it stronger,the 400 2 stroke can be turned out to a "high performances"
trail quad with about no problems,just get sure to get a forged piston in when you'll put the mods on.the more you add mods,the more you'll have to check and maintains well your quad,PIPE IT AND PORT IT!

 

right now o got a fmf gold series pipe and a turbinecore 2 muffler and v-force reeds,and a k&n filter,i guess rick will be the man to deal with seeing how he is there to listen to what u want and he tells you what will be best from there

 

My fault Will, I apologize!! [img]i/expressions/face-icon-small-smile.gif[/img] I jumped the gun there, you just got to watch out sometimes kids come on here saying this and that, Sorry. Hey just wondering how far Oxford is from Morganton anyway?? I am about 50 miles east of Asheville. That is a nice quad, oh yeh I got the bad info about no 2x4 from partsland... can't believe them sometimes. [img]i/expressions/face-icon-small-sad.gif[/img] Good answer on the bore Bubba. In my opinion if you were to go all out with the big bore kit, why not get the HPD Power valve kit and get some big HP??

 

Hey NCScramber Oxford is about 320 miles from Morganton about 3.5 hr drive. I only way i would do a BIG BORE kit is if you are going to Drag Race you need it for the Torque Other than that just say with the stock bore! It is very torquey and i love it! I can pull any banshee or 250R off the line (unless the banshee is a full mod) and out run them in 300' drag they might out run me on top end but i have the bottom end torque to kill them off the line! Have Fun! [img]i/expressions/face-icon-small-happy.gif[/img]

 

Like the others said, the big bores have some inherent burps, glitches of their own. Greater tendency for reed munching. If you want to do it fast, and right the first time, go with the HPD race-mod. Your throttle response with that pipe is instantaneous. Also retard your timing (with that mod) 2 degrees....a couple of free HP. Ixnay your oil injection, change out your steel front bumper for an aluminum unit off a 4x4. Get rid of the floorboards...add nerfs if you want. Run a K&N slip-on with an outerwear (toss the airbox). Remove your cooling fan, and run Red Line Water Wetter mixed at the suggested ratio...but watch out in the fall, it doesn't have anti-freeze protection. If you can spring for the power-valved race-mod, that's even better. There's some new clutch technology coming out that'll really wake things up also. You can get the White Bros battery eliminator kit (capacitor) route your wires up front where your oil injection used to be....and last but not least, with the W/B kit, get rid of the starter. Even at 15.5:1 compression, these things pop right off with the pull-start.