i have a 400ex and i put 2 new sprockets on them andi bought a non oring chain and now my chain always falls off when im riding mainly when i hit a bump or doing a wheelie but it has done it like 5 times i had to buy another back sprocket because the chain tore it up when it feel off. My sub frame is bent but i dont think tht is the problem because the guy before i bought it had no problem. Could the bearing be out or something like that i dont no very much about te 400 i just got it 3weeks ago so please help i need to ride thanks

 

for somereason ur front sprocket could be loose, u have to tighten ur chain if that dont work nuttin lock tight cant fix j/k

 

sounds like your chain is a little loose....try tightening it a bit better...
oh yah and that non-oring chain won't last you six months if you ride frequently, although they cost 2 times as much they last 3-4 times longer
throwing a chain can be a very expensive problem if you waste a case

 

Sounds like your chain tension is way too loose. There should only be about 1 inch of freeplay in the top of the chain. It should barely come off the sproket teeth. Maybe one of your sprokets or your sproket hub is bent. Just a thought

 

for a 300ex there should be 4 cm of play so i guess the 400ex would be the same. Why dont you have an o-ring chain? The quad comes with one stock.

 

Dyno's have proven more power gets to the rear wheels with a non o-ring chain..and for $12 a pop you can't go wrong....maybe I am just a cheap *** bastard but I will stay with the non o-ring.

 

Yah until your POS chain breaks and wastes your case half
I like the pics...kep em coming

 

I just bought a nice pro design case saver...I could get 2 chains for the cost of that, and still hav some left over...LOL !

 

I have seen this before... check your swing arm bushings!! If they are wasted and it's moving around it will toss the chain.

 

I agree with spincycle, this happenned to me before. With quad stationary hold the grab bar and move the quad left to right while watching the swingarm pivot point, you should see no foreward and back movement at that pivot point, if you see any time for new swinagarm bearings.

Go with Pivot Works, they are way better than stock.