Stock jetting on a 400EX anyone know what it is?

Can anyone tell me what the stock main and piolet jets are? Aren't they like 150 or something. I bought my bike used with a WB pipe and silencer on it and I need to take the carb apart to see if the guy I bought it from has change the jetting for the pipe. Any help would be great.

[buckeye400ex]

I just rejetted mine when I put the K&N Power up kit on it. I took the stock 148 main jet out and put a 146. It runs much better now, I had fouled a plug with the stock jetting and the White Bros. pipe.

how important is it to change the smaller jet? I have noticed that in most quads you never need to change the piolet jet. You can usually just change the main. Did you have to change the smaller jet?

[Taco]

Originally posted by Honda4hundredEX
how important is it to change the smaller jet? I have noticed that in most quads you never need to change the piolet jet. You can usually just change the main. Did you have to change the smaller jet?

[Taco]

Originally posted by Honda4hundredEX
how important is it to change the smaller jet? I have noticed that in most quads you never need to change the piolet jet. You can usually just change the main. Did you have to change the smaller jet?

Most people go ahead and swap in a 40 Pilot jet because the 38 it comes with are already lean and contribute to alot of the cold starting problems. Also Buckeye you cant compart the dynojet #s with the stock keihln numbers. The dynojets have a different way to meter fuel .ie taper etc.

[buckeye400ex]

Taco, so you are telling me a Keihn 148 is different from a DynoJet 148 huh? If so, that is news to me and the most ridiculous thing I've ever heard. That's the equivalent of saying a 265/75R/16 Goodyear is a different size than a 265/75R/16 Michelin. I'm not saying you're wrong, I don't know for a fact, but that sounds silly to me. How confusing can you make it?

Also, Honda, I did replace the stock needle in the carb to with the one provided with the jet kit. However, I don't know the difference in numbers since neither was labeled. I did put the E-clip on the 3rd groove of the needle.

My quad runs great now, I do know that for a fact.

[Taco]

I do not understand why they are sized differently either but its true thats why they come supplied with their own needle also to match the different taper. In my 400ex all i have done is drill 3 3/8in holes in the airbox and the rear baffle of my stock exhaust and i am running a keihln 155 main.

[Guy400]

Buckeye, he's right. Dynojet uses a completely different numbering system than Keihn jets. A 150 Dynojet is different than a 150 Keihn. I could me mistaken but I believe that the Dynojet's are numbered a little higher than Keihn (ex. A 165 Dynojet would be something like a Keihn 155).

[400exRacerX]

Yeah Guy is right, Dynojet and Khien jets are completely different in sizes.

So if a 155 Dynojet is different in a 155 Keihn then which jet is used stock in the 400EX? The dynojet or the keihn? For the stock jetting I got the numbers 148 main and 38 pilot are these numbers correct for a stock Honda 400EX Carb? Thanks for all the help guys.

:(

[Guy400]

Those are Keihn numbers if they're the stock jets you removed.

[buckeye400ex]

WOW, learn something new everyday. I have not been able to find anything to dispute it or much less convert Keihn into Dynojet numbers, I will keep looking though. So if the Dynojet numbers are that much greater than Keihn (Just for arguments sake..)
say by a value of 10, then the 146 Main Dynojet I put in to replace the 148 Keihn, is actually equivalent to a 136 Keihn. (Guy if your "guestimate" is accurate).
Come to think of it, I have many other Dynojets still in the package that came with the K&N Power Up Kit. A Dynojet 158 should be about the same as stock then. I'll check it out and get back with you.

Sorry but this cracks me up, why make it so freaking complicated, like a carburetor is not complicated enough already.

[Guy400]

buckeye, you are correct. When I jetted my cousin's EX we removed the factory Keihn jet and installed a 165 or 170 Dynojet main (for a HMF slip-on and no lid).

[Chef]

now wait a minute here, so your saying by putting the 146 dyno jet in, he went to a keihn 136 main? so with a freer flowing exhaust, he went down in jetting, a long ways down in jetting, and the bike isnt running lean?:huh

[buckeye400ex]

Well this is interesting. It appears that the 160 Main Dynojet is about the same size, (Just eyeballing it) as the stock 148. I thought that I was running too rich prior, since I had fouled a plug and it was black black.... So... after following instructions on the Stage 1, I just realized I missed one step. I did not put the main jet adapter in, the DJA001 that was supplied with the Kit. I just put the DJ146 Main jet in. (as suggested for below 3000ft, as I am in here in Ohio )

DOH!! I wonder what the difference is. My quad is running very good though, pulls hard from the lower end all the way thru up to the top end. ???? I'm running my airbox lid by the way.
This has certainly been a learning experience. I'm going to add the Main jet adapter and see what happens then.

It does sound like normally you go for richer jetting with a K&N Filter and after market pipe. ????:huh

www.dynojet.com

Maybe the adapter makes up for the smaller jet???

Guy is my cousin and we put the DynoJet 170 main in my bike when we piped it. The 148 stock jet that you see is the Keihn #. DynoJet is the only company that uses the other numbering system. It is stupid if you ask me!