Full exhaust jet help

[TBrunk]

Hey, I just got a Full Yoshi Exhaust system.

Bike is a 2001 400ex.
Stock Motor.
Uni Filter with drilled holes.
Full Yoshi Exhuast.
500ft above sea level.
Temp is around 60-95 degrees.

I have a Dynojet kit. I was wondering if yall could point me in the right direction for the jetting. Thanks.

[08400EX]

Originally posted by TBrunk
Hey, I just got a Full Yoshi Exhaust system.

Bike is a 2001 400ex.
Stock Motor.
Uni Filter with drilled holes.
Full Yoshi Exhuast.
500ft above sea level.
Temp is around 60-95 degrees.

I have a Dynojet kit. I was wondering if yall could point me in the right direction for the jetting. Thanks.

Easy, return the Dynojet Kit, go to the closest Honda Shop get a 42 Pilot Jet and a 155 and a 158 Main jet. Try the 158 first, then Chop Test and go to the 155 if necessary (possibly in the hotter temps).

[TBrunk]

well I bought the dyno jet kit online...so returning it might be a bigger pain. Should I try the same jets with the dynojet kit?? Thanks for the help

[08400EX]

Originally posted by TBrunk
well I bought the dyno jet kit online...so returning it might be a bigger pain. Should I try the same jets with the dynojet kit?? Thanks for the help

Return it or sell it on Ebay.

You already have an adjustable needle, so there is no "gain" with the DJ needle. Dynojet doesn't make the proper format Main jet for our 400s, so they send you an adapter with a generic jet. So you will forever be stuck with jets not designed for your carb.

Quite frankly, that is BS, why support a company by buying a product that they will not even make specifically for YOUR quad??

You can buy the proper main jets for $5-6 each and they will NOT work with the DynoJet "adapter" and needle. See what I mean!

They also use a different sizing designation so that makes even more confusion.

Dump it.

[JOEX]

^^^Agreed:)

[08400EX]

Originally posted by JOEX
^^^Agreed:)

Crap, I already PM'd him that you were a potential buyer :devil:

[JOEX]

Originally posted by 08400EX
Crap, I already PM'd him that you were a potential buyer :devil:
That's okay, I have a spare dollar:p

[CarGuy7a]

i don't know why everyone bangs on dynojets. i've ran em' in mine ever since it was new without any problems. the reason they're jets are tapered different is to help eliminate possible dead spots throughout the powerband and to help fuel atomize better.

not to make it sound like i'm a dynojet freak or anything b/c right now i am experimenting with another carb with Keihin jets in it and i'm going to compare them to see if i can tell a difference.

[08400EX]

Originally posted by CarGuy7a
i don't know why everyone bangs on dynojets. i've ran em' in mine ever since it was new without any problems. the reason they're jets are tapered different is to help eliminate possible dead spots throughout the powerband and to help fuel atomize better.

not to make it sound like i'm a dynojet freak or anything b/c right now i am experimenting with another carb with Keihin jets in it and i'm going to compare them to see if i can tell a difference.

I understand what you are saying, and I never said they didn't work.

But, one little silly example to help you understand what I was saying...

Who do you really think knows more about making a Carburetor needle.??

A Dynamometer manufacturer making dynos since 1972 and selling "rebranded" jets kits mainstream for maybe the last 8-10 years?... or Keihin, a Carburetor manufacturer that has been making carbs since 1947??

When DynoJet tries to convince you they can do it better than Keihin, that's called marketing.

I have used DynoJet Jet Kits in a few Bikes/Quads, and I thought they worked great too.. until I removed them and put the stock parts back in. When I did I suddenly had a better starting and running Bike/Quad in all climates and conditions. Sometimes you will find the "hype" creates an expectation that tricks your mind into believing it is better, just because the marketing has convinced you it is.

Ironically other DynoJets kits I have used do not require jet adapters, but their kit for the 400EX does. If they can't make the correct fitting parts they should not sell the kit. Way too many XR400s and 400EXs out there for small production numbers to be the reason. I suspect their supplier doesn't make the correct parts so they "threw" together something from other more common parts.

Again, I don't think the DynoJet kits are bad, but I don't care for patchwork products there require adapters to fit/work properly, and certainly not in a precision product like a carb.

On the other hand, I personally wouldn't buy a Dynamometer from Keihin either :-)

[JOEX]

The biggest issue I have with the jet kits is the price. I don't know what they are going for now but they were around $50.

For the average rider, which I think the kits were marketed to, they only need 2 or 3 mains and one or two pilots which can be purchased for about half of what the kit cost which do not even include any pilot jets.

[TBrunk]

Well, I guess I sell it on ebay like you said. So all i need to do then is just switch out the main and pilot jets out and I dont have to mess with the needle or anything.

Ill be heading out to the honda dealer to get the jets and see how this exhaust system helps out. Thanks

[08400EX]

Originally posted by TBrunk
...... So all i need to do then is just switch out the main and pilot jets out and I dont have to mess with the needle or anything.



Correct. Even if you do need to change your needle it is adjustable just like the DJ would be. From others with setups similar to yours you will most likely not need to adjust it. But, a midrange chop test after you install the other jets will tell you for sure.

[TBrunk]

When doing the chop test, does the pilot jet even effect this or is it mostly just the needle and main jets??

And lastly, want to make sure I understand the chop test. Run a new plug and accelerate to WOT then pull clutch in and kill engine. Pull the plug and examine the color. Depending on color will determine if I need further adjustment.

I appreciate the help. And will start out with a 158 main and chop test it.

[250exkid]

ok atvs r built f'ing cheap! i tryied getting my needle out to put a dj needle in it but the screws are striped.... so can i use the DJ main with the stock needle? and a keign pilot?

[2muchquad]

Yes you can use the stock needle with dj jets