The title explains it let em fly. any problems you've had or mistakes you made on it.

 

take the swingarm bolt out when the bike is new and grease the heckout of it. other wise it won't come out a few years later.
change oil frequently

these aren't really problems. i haven't had too many.

 

Problems I have had with my 99 400 EX:

It's falling apart.
The stock plastic totally sucks, breaks very easily.
The stock rear shock exploded on me.
Stock clutch totally sucks.
Wires keep getting cut or broken, still can't figure out what causes this.
The factory starter just took a crap.
Stock axle is junk, but alot better than most other quads.
The subframe is extremely loose, and I can't tighten it up.
Stock handle bars are junk.
Basically, these don't age to well.

Mine is 5 years old and feels like its 80. Reminds me alot of an antique.
I have taken pretty good care of it.

I always made sure everything was tight, all fluids were good, then all at once everything just falls apart.

I need a job so I can get a new quad really bad.

 

Nothing major! It's an 00 with a lot of hard a$$ desert miles on it!

A frayed wire to the headlights that kept shorting out and blowing the fuse. Can't get the parking brake to work anymore (may just need a major adjustment). Clutch has gotten awful stiff (may just need a new cable). Absolutely nothing else!

Realistically, it is probably one of the best machines ever made. The old Honda 300 utility would be my other choice for that title.

 

axle bearings wore out after goin through water a couple times, the subframe seems to get loose often. other than that its holding up pretty good for how bad i beat the sh*T outta it.

 

most of the problems on mine were from the previous owner who abused the crap outta it: worn out pads and rotors, blown shocks, worn out A arm bushings, weak a arms, stretched out cam chain, cracked airbox supports, bent spindle, worn out swingarm and rear axle bearings, seized swingarm bolt

but the only problems I have had are the following: shorted out headlight wires, wore out front spindle bearings, bent steering stem

overall it's a great bike and I wouldn't trade it for anything, i might swap out the engine next winter but i plan on keeping the chassis for a long time, it's just about the best racing chassis out there seeing as how it's based off the 250r and there are so many mods and accessories for it.

 

in motocross no one ever uses the 400ex chassis, its always the 250r or them lonestart chassis, you may think its one of the best but plenty of mx racers will disagree with you, but you are right it is a very good quad for all around cause its VERY easy to throw around is small which is better, but it just doesnt have enough power IMO your 440 will though but not stock bore ones

 

Hmmm problems with a 400EX???Lemme think for a moment....Kinda cold natured,the seat is a little hard to replace and get hooked on the lil ****,thats all. No probs mate!
Great Bikes!

 

My buddies hi comp stock bore exploded the clutch basket and assembly. That sucked...took an entire day flushing the motor out to get all the metal flakes out.

 

The major problem with my 400ex is I'm on the puter not the quad.

I still like it more then my 450r.