Im confused......

[ridehonda400ex]

Okay so im getting an HMF sport series slip on pipe for my 400ex. everything else is stock. So heres where im confused, my dad was talking to the dealer about slip on pipes and the dealer said that there is no need to rejet the carb unless its a full exhaust system. well im not getting the full exhaust. but i think the dealers are wrong

[quadrider2112]

it will need jetted i wood think and i wood go ahead and to off the airbox lid too.

[sixer3]

it definitely will need to be rejetted. whether you remove the airbox lid or not

[CJM]

Always rejet. Dealers arent all that bright btw.

I took my 416 down to the dealer after calling and they assured me they could tune it. All they did was play with the notches on the needle and adjust the air/fuel screw. I needed much larger jets and they screwed me-I paid 2x for nothing.

[Scro]

Rejet, and never take advice from that dealer.

[ridehonda400ex]

i knew i was right. worthless POS dealers.

[wilkin250r]

Well, yes and no.

Checking your jetting is always the safe road. Some quads are jetted rich from the factory just to be on the safe side, some are actually jetted lean from the factory to pass emissions testing. If you're slightly rich from the factory, you might very well be dead-on with a slip-on pipe. I've had several times I've rejetted somebody's quad for a slip-on, and ended up with the stock factory jetting.

Filter and airbox mods, on the other hand, drastically change the vacuum signal to the carb. If you change to an aftermarket filter and eliminate the airbox lid, and still end up with the stock factory jetting specs, then you didn't jet correctly.

[ridehonda400ex]

well see i think i might not have too, unless i get a k&n. because my fuel screw on my carb is all the way in. i know i should go down a size but its runs good lol so im happy :)

[TheLane]

i can tell you on a 400ex your most likely going to want to, going from the stock exaust to a slip on will COMPLETELY change the way your bike breathes and the amount of backpressure your getting.

You pretty much just spent a ton of money on a preformance part to make your bike not preform by skipping this easy process.

[ridehonda400ex]

yeah im gunna rejet it. i have the kit on the way and once i get into the top end with it not jetted it sputters

[ridehonda400ex]

could somebody tell me if what a good main jet would be for 600ft elevation, closed air box, uni filter and a HMF sport series slip-on? and do i need to change any other jet? and does the float need to be adjusted?

[TheLane]

Buy the dynojet kit, their customer support is awesome and they will tell you what to use if you call them.

[sixer3]

Originally posted by ridehonda400ex
could somebody tell me if what a good main jet would be for 600ft elevation, closed air box, uni filter and a HMF sport series slip-on? and do i need to change any other jet? and does the float need to be adjusted?

the float is not adjustable on your bike so no to that

I personally would go up on the pilot jet, I think the stock is maybe a 38? I forget but go up a size on that. 2.5 turns out on your air/fuel screw

start with probably a 152 main jet (kehin) the dynojet numbers are different

[ridehonda400ex]

yeah idk what kind of jet kit it is. my dad got it for me for christmas and the shipping got messed up and it just shipped yesterday and i thought the floats are adjustable in the 2001 400ex's? i dont think the newer models are adjustable tho

[sixer3]

Originally posted by ridehonda400ex
yeah idk what kind of jet kit it is. my dad got it for me for christmas and the shipping got messed up and it just shipped yesterday and i thought the floats are adjustable in the 2001 400ex's? i dont think the newer models are adjustable tho

It's possible that I'm wrong, I owned an 05 so you could be right on the float thing, did he buy you a jet kit or just one jet?

[ridehonda400ex]

he bought the kit from jets r us with like 10 jets and the stainless allen bolts. also should i buy a new gasket for the bowl? or will the old one be fine if i dont rip it.

[sixer3]

Originally posted by ridehonda400ex
he bought the kit from jets r us with like 10 jets and the stainless allen bolts. also should i buy a new gasket for the bowl? or will the old one be fine if i dont rip it.

ahh, I think I've used those jets they are kehin numbers so you're good to go there and yeah your stock bowl o-ring should be fine just be sure to keep it clean and clean the surfaces before putting it back together and of course don't rip it, should be fine though

[ridehonda400ex]

i seen they were genuine so thatll make things easier. thanks

[HondaPohl]

There is never a specific jet that anyone can telll you. A jet kit will give you a load of different jets. Its a matter of test and tune brotha! Who knows, you might even have to drill your biggest jet out.