2002 Honda TRX400EX couple questions

well i went and bought my first sport quad. a 2002 honda TRX400EX quad for 600 bucks. it needs a new bearing carrier, tail light, battery box,battery, airbox lid, muffler, chain and 1 more set of brake pads. this is it i just got it home.

my questions are,

1. on the rear end of all the 400ex's on the left hand side i see a cyclinder type deal on the sub frame what is that since mine doesnt have it?

2. when i put an after market exhaust on here do i need to rejet? since all these pipes ive been looking at so no need to rejet blah blah blah

3. on the airbox theres a 2nd tube running from the box to the top of the motor what does that do and do i need it? since theres no filter on it so i didnt figure it did anything.

probably the best guy to ask is ck1999_400ex, i can't believe he's not on here posting (LOL).

the cylinder thing should be the stock tool container ...and yes you should rejet and the the tubes slould be the air intake tubes 1 should run up under the gas tank if i remember rite and the other i think is a vent that should go to the vent on the rear top of the motor case and there is a drain tube that is in the bottom of the air box that is to let and water out ...

The other hose that comes from the top ofthe motor that goes into the airbox takes motor fumes and blowby and reburns them. There should be a check valve but not 100% sure

As CK said a rejet is a must. No room for error on an air cooled. 400ex come from the factory lean so any additional air flow needs added fuel. Without it pinging or burnt valves can occur.

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Also the cylinder / tube on the rear is where you stick your Flesh-light (google it) for those lonely nights

Originally Posted by oxidized_black probably the best guy to ask is ck1999_400ex, i can't believe he's not on here posting (LOL).

The 2nd tube does help keep dirt out of the airbox but my friend had one on his he took it off. he said it felt like it was able to get more air to the engine

* Added full year,make, and model to thread title.

Originally Posted by Fogel well i went and bought my first sport quad. a 2002 honda TRX400EX quad for 600 bucks. it needs a new bearing carrier, tail light, battery box,battery, airbox lid, muffler, chain and 1 more set of brake pads. this is it i just got it home. my questions are, 1. on the rear end of all the 400ex's on the left hand side i see a cyclinder type deal on the sub frame what is that since mine doesnt have it? 2. when i put an after market exhaust on here do i need to rejet? since all these pipes ive been looking at so no need to rejet blah blah blah 3. on the airbox theres a 2nd tube running from the box to the top of the motor what does that do and do i need it? since theres no filter on it so i didnt figure it did anything.

the round container you see is the fractory tool box the the tube you are talking about is a vent to releave the crank case pressure and recirulates the air back into the air intake boot alot of people will disconnect this and replce it with a small micro filter that can be bought at oreilys auto parts do not leave open drit and grimm will result in engine damage. it suggested to jet most carbs with after market pipes dealing with air/fuel and back pressure that is needed to make any motor to run.