Dynojet

[EX4me]

Do the jets run smaller or larger in these kits vs. the stock ones. I'm running a Dynojet 170 main right now & I'm running a little lean. Just can't remember if they run smaller than the mikuni jets.

[cals400ex]

i don't know how they compare to mikuni jets, but they seem to run larger than keihin jets. these honda's have keihin carbs and jets in them.

how do you know your running lean? plug readings aren't the most accurate these days. also, you could be lean on the pilot jet, fuel screw, needle taper, needle diameter, needle clip position, mainjet, etc....

[EX4me]

I didn't mean Mikuni. Guess that's what happens after working all night. I have a 99 400ex with Ross 89mm 11:2.1 piston with Advanced tapered sleeve, Hotcams stageII, HMF exhaust, ported & polished head, Uni filter with air box lid on, WB rev box. Stock carb (4 now) with 42 pilot jet, Dynojet 170 main, 2.5 turns out on air mixture screw, clip in stock position on needle. 50/50 mixture of CamII & 93 Octane. Plug is a little white but not burnt up. Not tan in color like I'm used to.

[EX4me]

Forgot to add that I'm running a colder NGK dpr9z plug.

[cals400ex]

was it a light color after full throttle, mid throttle, idle, etc???

i would drop your needle clip to the 4th position for sure.

[EX4me]

full throttle.......

[cals400ex]

my plug never turns up brown at full throttle either. i will see a slight change in color right on the bend of the plug. this is where i jet my bike too. if the color change is below the bend, go up a size or two. if it is above the bend, go down a size or two.

[ewalker302]

A DJ(142) is the same size as a Stock 400 Keihin(148)

I have no idea if the size difference stays the same numerically, but if it does, a DJ(170) would be comparable to a Keihin(176), If there is such a Keihin size.

:bandit:

[northeast400]

How do you know the two sizes are the same

[ewalker302]

By comparing the orfice, or the opening in the jet itself, and by running them, tuning.

I'm not saying that it's exactly to the n'th degree identical, but its very close.

:bandit:

[Evan400ex]

It seems like you should be running rich with a 170 main. I have a 416 with alot of engine work and I run a 168 keihin main. I used to use the dj's but never could get it jetted correctly. I had a dj 170 main in but was way to rich. I guess the only thing you can do is drop the needle.

[northeast400]

I have gone back and forth from dynojets and stock type. here is what I found works good for me. If I run dynojets. I use a 155dj main, with no airbox lid. I run a 146dj main with the lid on. needle in 4th position for both. If I run stock type. I run a 165main with the lid on, and a 180main with the lid off. I must say I also don't notice a power difference with the lid on or off.

[dariusld]

Originally posted by northeast400
I must say I also don't notice a power difference with the lid on or off. :rolleyes: