Jets

[trx400exrider14]

What are the best brand of jets for a stock 400 carb?

[400exshop]

just go to a dealer and tell the what you are working on and tell them what size jet's you need ......

[trx400exrider14]

what you know what kind of jets i need with an 11:1 piston and stage 2 hotcam? with airbox on,stock intake,twin air air filter? Its a stock carb with i believe stock jets with and fmf powercore IV 2

[400exshop]

PS. sell that carb and get you a fcr from a yfz450 it will go right on with no mods .......... it the same as if you was to buy a sparks carb there 39mm's.....

[400exshop]

stock is a 145 i think..... i would try a 148 and a 150 - 152 some jets go by 5's

[trx400exrider14]

stock is 148 i thought,and is that all ill have to replace is the main jet?

[Honda#4]

stock is 148 main.

[trx400exrider14]

Originally posted by Honda#4
stock is 148 main.

What would you suggest with my setup for jets?

[hocman123]

well the name of jets u would want is Keihin jets the gyno ones dont really work that great. i would think u would be in the 165-158 range on the main and a 42 pilot. i have 11:1 406 with a stock pipe closed lid and a uni and i am good with a 160

[trx400exrider14]

I think im gonna take it to my local dealer and have him jet it properly,so i dont have to waste money on new jets

[hocman123]

the best place to get the jet is this place if u dont have a local dealler http://www.jetsrus.com/a_jet_kit_atv/honda_400_TRX400EX_1999-2008.htm

[400exshop]

With my build i run a 160 to 165 main jet and i run a 440 with 13.1 comp. and +1 valves p&p head stage 2 cam and i run VP Race fuel Q16 in my bike.....

The best thing to do is take the bike to a shop that has a dyno.....That is truly the right way to jet one...... Just taking it to any shop thay will be doing the same as you would.... put a jet in and run it if it runs good thay will charge you out the back side and there mite be more power to have with it jeted right...... Just my .02cent....

[trx400exrider14]

Do I need bigger valves with a bigger cam?

[400exshop]

No you do not...... I did the valves for better flow and more power.

[trx400exrider14]

A 400ex doesnt have hotcam or valve shims does it?

[CJM]

400ex you dont shim the valves, you adjust them. SUPER easy to do as well.

[trx400exrider14]

So lemme get straight with all this,lol,I hone the cylinder, I drop the piston and cam in,i need to adjust the valves,put my new gasket on and im done?

[CJM]

It would be best to measure the bore and make sure its not out of round before you do anything else. Seeing as if its out of round you will basically blow it up shortly. Always pays to check it.

[trx400exrider14]

Is it hard to fix if it is?

[CJM]

If its no good you simply bore it-but a stock piston will not work of course, you need to get a larger one and bore it to match that piston.

[trx400exrider14]

Is it common to be out of round. It doesnt need a rebuild either. im doing it for the heck of it

[CJM]

Not usually, but its always a good idea to check it. All it takes is visit to machine shop, they check it for like 20 bucks and measure the piston to check it all and your done.

Or you can do it yourself with a bore gauge and a vernier caliper.

[trx400exrider14]

Does the bore gage just like spread out in the cylinder and measure how big it is?

[CJM]

Originally posted by trx400exrider14
Does the bore gage just like spread out in the cylinder and measure how big it is?

Exactly. What it will do is check the bore at various depths to make sure its in spec. Its always a good idea to check the bore when you instal a new piston.

In extreme cases (such as how mine was at a point before I rebuilt) with the stock piston in the bore I could clearly see past it-my cyl was egg shaped.

[trx400exrider14]

how much is one of these bore gauges?

[CJM]

Originally posted by trx400exrider14
how much is one of these bore gauges?

Depends, ive seen some as cheap as 50 bucks and some as high as 500. A machine shop would have everything needed and do it for a small fee as well