Honda 400 ex dyno jet

[tonymdfl]

Hey everyone im new to this site this is my first post, anyway, I have a 2000 honda 400 ex. I wanted to get some more power from it with out spending to much. I was thinking about a dyno jet kit. Any have any info on this and what jets to use for it. Anything will help, Also I was looking at the dial a jet , that seems alright to I guess. So far i have a white brother exaust , and a K an N air filter.

[Eviltanker]

Where you from and elevation? Don't buy a Jet kit. Just go to jetsrus or talk to Colby of C&D racing. Buy a few up and down and save yourself some money.

while you are looking on www.jetsrus.com read their faq's to the left...

i second the notion of staying away from dynojet kits

[tonymdfl]

well Im in MD so its not no kinda elevation but we went to PA this past weekend so thats a higher elevation.

[Eviltanker]

In Pa I'm at 502 ft. elev. That shouldn't effect you much.
Maybe start with a 40 pilot and a 150 main fuel screw about 2 1/2 to 2 1/4 turns out, needle on the 3rd.that should be a good start. Also search "plug chop"

[IcutMetl]

I have to disagree with the reccomendations against the K&N/DynoJet power up kit. Yes, it is cheaper to buy the needed parts seperately; no doubt. But, for someone who doesn't know a TON about that stuff, it makes it pretty damn easy.

I bought a K&N Power Kit for my 2001 400ex. I put on a Yoshimura pipe, and it needed jetting very badly. I followed the instructions in the kit to the "T", and kept it at 'stage 1' because I wanted to keep the airbox lid on. Worked like a charm and the jetting was spot on with very little adjustment needed. For me, it was a good choice, even though I ended up with a few jets that I didnt need.

stage 1, stage 2...those are contrived by dynojet...

the jetting process is the same with or without the dj kit, you just have a starting point...although many believe that the dj kit is the exact jet needed, not a starting point jet

read the faq on jetsrus and see why to stay away from dynojet...

also, don't bend the needle while celaning the carb...you will have to send the needle in while the determine if it is a "dj" needle. which takes about 4 days AFTER they receive it. after they charge you $8 for a new needle, then the mail you a needle back at $5 for shipping by putting it in an envelope. no cardboard or anything around it...just the needle in an everyday non padded envelope...luckily mine didn't get bent in the shipping process...three weeks after i mailed out my needle , i finally got a replacement back...good thing i didn't have any races in between...

oh, and i showed them the box, and the plastic baggie, with the needle number on it, that the needle came out of...knowing 110% it was a dj needle that i had...

[coryatver]

get jets that are made for your carb. keihin jets made by keihin for keihin carbs. Dynojets you have to use adapters and crap they really don't work very good. They make a killing off those kits from guys that are new to jetting.


To answer the first guys question get a 42 pilot jet. and 155, 160, 165 main jets. These are Keihin sizes! Dynojet sizes are measured different and do not match up even the chart thing does not match up perfect becuase they do not cross reference.
If you have the lid off you will probably need the 160 but it varies by bike, elevation, weather and that but that is what I would start with. Read the faq on that website and it will help you tune it.

[F-16Guy]

Originally posted by Eviltanker
In Pa I'm at 502 ft. elev. That shouldn't effect you much.
Maybe start with a 40 pilot and a 150 main fuel screw about 2 1/2 to 2 1/4 turns out, needle on the 3rd.that should be a good start. Also search "plug chop"

X2. That sounds really close for a 400ex with no internal engine mods, although I would probably start a little richer (152 or 155) and work back down just to be safe. I'm not a big believer in reading plugs for the average Joe to evaluate jetting; I think the performance of the engine is a much more accurate indicator of proper jetting, especially with all of the different fuel additive packages that companies put in their fuel. My advice is to start rich and work lean until you don't see any improvement or it gets worse, and then go back to the next richer jet. Always do the main jet first and judge the performance off of WOT runs, since that will pretty much eliminate all circuits but the main jet. Once the main is dialed in, adjust the needle for midrange throttle problems. You can move the clip and/or try needles with different tapers, but the stock needle has always felt pretty good to me.