I have 400 EX nad it is time for rebuild. I was wondering if any one has any info on the big bore kits. Which one works and wich one does not . I want to run pump gas. I mainley do woods riding and hill climbing. Not sand dunes. What have you learned? I could use some help, Thanks, Luckywilson

 

I installed the IMS 440 kit on 2 of my Ex's. The kit is awesome. I also installed a racing cam and FMF powercore4 pipes. I had the quads out in Glamis this weekend and smoked several stock 400's
and I even beat one that had been ported. I am very happy with the results. I maily use super unleaded gas but this weekend I used 1/2 race gas and 1/2 super....the Quad did ride much better. (no engine ping) I have heard White brothers does a great job with their big bore kit. They do everything from rev unlimiter to pipes to cams....and excellent package (assuming you have the money). But make no mistake..the hop up kit, no matter who you choose, is totally worth it!

Good luck

 

426 It is more bang for the buck. Get a 3mm over piston. Send your cam to web cam and get a 450-451 grind. This will cost the same or less than a 440 kit after you pay for the overpriced piston and sleeve and pay to have the sleeve installed. Port match the intake to the head Honda's alignment there sucks there is definatly more possibility for smooth air flow. Get a DMC or other good pipe. Also a good three angle valve job and rev limiter. My combo hasnt been beat on sand mountain by a single cylinder Four stroke.
Including the big yellow slugs with a RW stage 1 Kit. A 440 kit is only actually 435 cc's Price everything out and see if you dont find the same thing. I ride on sand, salt flats, desert, and wooded mountain trails and have never had a problem any where with this combo.

99 426ex , Web Cam, FCR carb, CT revlimiter, DMC exhaust, XCT's ,K&N, One kit,

http://www.trxoutlawz.com/

 

I took my motor and a buddys motor down to PRO FAB ATV (740)654-0734 in landcaster ohio. to
have it bored to a 426, with a 10 half compresion
ratio, a cam, 3 angle port job. the guy said this
will be a very reliable motor.

$150 for the piston kit
$169 for the cam
$375 for the 3 angle port job
$99 for the rev box
$45 for the ??? i cant remember what its for
$150 for him to tare the motor down and put it back togethere, our you could just send him the top of the motor and it would save you $150
for a total of $988.00 plus tax.
since i took 2 motors down he said he would give us a deal and take the tax off!!!!!

 

CT offers a pretty decent 440 kit for like 1100. Go to there site

ctracing.com/400ex.htm

 

426ex,
just wondering if you changed the carb.If not what jetting do you run with this package.

OZ_400ex

 

hey oz_400ex i have the dyno jet kit for it and
i use the 146 jet. i'm suppose to get my motor back this week. but no i don't have a carb on just yet need some info on one before i by one,
i see that elderblock is coming out with one,
i will wait and see.

 

Is the 40 over the same as the 3 mil over piston? If not where can you get the 3 mil pistion? I was thinking Powerrolls for the 440 kit but what you said sounds interesting I might go that way. Thanks.

 

The 3mm over is what you use to make a 426 It is not the .040 over piston. I got a piston kit from rec unlimted for apx $100.00, alot cheaper than a 440 kit (436 cc). Save your money buy a 3mm over weisco and put the savings into the cam and head work. This combo likes to be revved get a rev limiter.

99 426ex , Web Cam, FCR carb w/ twist, CT revlimiter, DMC exhaust, XCT's ,K&N, One kit, Renthal bars, DG nerfs, Armidillo Swingarm plate, 8 paddle Haulers

http://www.trxoutlawz.com/

 

I've scene air race down to big sand his bike beat another 440ex and seamed to have less mods than the others.