400ex Jetting Prob.

[sprtrx300ex]

I have an 03' 400ex. I put on a White brothers R-4 slip-on and a WB powerfiter. I left the lid on.

Right now I am running a DJ146 Mainjet, DJ needle on the 3rd notch (perfect setting), and a 42 pilot with 2 - 2 1/2 turns out on the fuel screw. When ever i go to start it, I have to ump the throttle 3 times or so and try to start it. I have to do this about 3 times to get it started. Once its started, when I rev it, It pops real loud. Its like a loud CRACK noise. It also shoots out a little flame. I hold the throttle at around 1/4 throttle until it is warmed up. When I do this ths it pops a little untill it is warmed up. I check the plug, and its always black. So I installed a new one, let it idle for about 3 min, then checked it. It was a light shade of black. So I installed it again and went riding for about 5 min. then checked it again. It got getting blacker

Also, as I'm warming it up i'll rev it up, and a little bit of black smoke puffs out the back. It only does this as im getting it warmed up.

So, does anybody have an idea as to why this is happening? I think that the pilot is too rich and it is causing the excess fuel to "explode" inside, there for causing the flame. What do you think?

[AtvMxRider]

I don't know much about Dyno jets but I would try going down on the main und see if it cures the problem.

[cals400ex]

get the bike to full temp by riding it for 10 to 15 minutes or so.
let the bike idle for 2 or 3 minutes. turn it off and check the plug color.
then take the bike out and ride it around 1/2 throttle without going over 3/4 and not going lower than 1/4. after you went down a long road or filed, pull in the clutch quickly and shut it off. check the plug.

do the same thing but this time floor it all the way through the gears and keep it pinned in 5th for a little while. pull in the clutch at full speed and shut it off. check the plug.

if the plug is black at idle, your rich on your pilot/fuel skrew
if the plug is black at 1/2 throttle, your rich on the needle
if the plug is black at full throttle, your rich on the main.

if the plug is white at any of these throttle positions, your lean.

[sprtrx300ex]

After 10-15 min or riding, the plug is all black. I dont see how a 146 main could be too rich.

I did the idle test once for about 2 min. and got a light shade of black. I did it again with a new plug for about 5 min, and got no color. What else should I try? Any ideas on the flames/ loud poping noise?

[2001400ex]

Originally posted by cals400ex
get the bike to full temp by riding it for 10 to 15 minutes or so.
let the bike idle for 2 or 3 minutes. turn it off and check the plug color.
then take the bike out and ride it around 1/2 throttle without going over 3/4 and not going lower than 1/4. after you went down a long road or filed, pull in the clutch quickly and shut it off. check the plug.

do the same thing but this time floor it all the way through the gears and keep it pinned in 5th for a little while. pull in the clutch at full speed and shut it off. check the plug.

if the plug is black at idle, your rich on your pilot/fuel skrew
if the plug is black at 1/2 throttle, your rich on the needle
if the plug is black at full throttle, your rich on the main.

if the plug is white at any of these throttle positions, your lean.


Listen to cal...he's a carbeurator genious:p

[sprtrx300ex]

ive tried that, and got these results

After 10-15 min or riding, the plug is all black. I did the idle test once for about 2 min. and got a light shade of black. I did it again with a new plug for about 5 min, and got no color. What else should I try? Any ideas on the flames/ loud poping noise?

[2001400ex]

The popping is defenitely your jetting, unless maybe something else, I'm not sure if the popping means that you're too rich, or too lean to tell you the truth. Right now, where I live the temperatures have been preety warm compared to what they were about a month ago when I jetted my quad. The average temperature was about 20-25* On the stock jetting my 400 wouldn't start. I had to rejet, keep in mind I have a HMF exhaust so yours may be different. I ordered a 155 main jet from HMF, took out my 38 pilot jet, installed a 42, turned my air-fuel mixture down to 2-1/2 turns out from 3-1/2. Right now since my quad is jetted for colder temperatures then it is right now on deceleration I'm popping and I pop about 3 times when I give my quad gas to make it warm up. It's gotta be the jetting...I just don't know if that means that you're too rich, or lean. Hope that helped some?

[Aceman]

Do what cals400ex said. Your only going to figure out which jets/needle needs to be adjusted by doing a plug chop. If you put in a new plug and it's not showing any color yet, ride it around some more and then do the plug chops.

[sprtrx300ex]

ok,
also, Are the flames caused by a rich or lean mixture?

[cals400ex]

it is very possible to shoot flames if your not running a spark arrestor.

it may take some time on the plug before you get a reading. i know this goes against the rules, but i always get the best results by using my old plug. it seems to show readings the best.

you say you ride it for 10 to 15 min and the plug is black. well your probally getting readings from your pilot/fuel skrew, your needle and your main. so that tells us nothing unless your only riding at one particular throttle position. also, make sure your carb is clamped on tight and all the bolts on the carb are tight.

[Colby@C&DRacing]

Ya cal is a carb guru he learned it all from me jk LOL.

Doing a plug check with unleaded fuel in not really very acurrate.
Sound to be a little rich. the popping can come from air leaking into the pipe at the head or the joint between the headpipe and silencer. Also check your valve clearance if you have leaking valve you will have low comp and it will cause a rich condition. Just a couple of things to check

:)

[sprtrx300ex]

I checked all connections (carb, exhaust, etc.) and they are all sealed. I put it in nuetral, and let it idle for about 5 min., and I used a leaf blower to keep the engine cool. I checked the plug and it was again, a light black color.

I am 100% sure that the needle is in the proper position, and Im pretty sure i have the correct main jet.

Its about 70 degrees around here lately :cool: . About how many turns out should the fuel screw be with a 42 pilot, under 3000 ft, and airbox lid on?

[2001400ex]

Get a smaller pilot jet, that's why you're fouling your plugs or they're becoming so black, a 42 is way too big if it's 70* out, get a size 38.

[cals400ex]

Originally posted by Colby@C&DRacing
Ya cal is a carb guru he learned it all from me jk LOL.

Doing a plug check with unleaded fuel in not really very acurrate.
Sound to be a little rich. the popping can come from air leaking into the pipe at the head or the joint between the headpipe and silencer. Also check your valve clearance if you have leaking valve you will have low comp and it will cause a rich condition. Just a couple of things to check

:)


hey, you do know you taught me a lot about jetting. i have probally called you one time too many about a jetting question. your website is very helpful when trying to learn how to jet a carb. the only thing on there that seems to confuse people is when it talks about the air skrew. some of the people are trying to turn the fuel skrew in on the 400ex to richen the carb, thinking it is an air skrew. besides that, it is an excellent article.


i actually run a 42 pilot jet in the summer months with my lid on, however i need to be less than two turns out on the fuel skrew for the jetting not to be rich.

i would agree with colby, some of the fuels don't give good plug readings. i found the shell fuel here to give the plug a yellow color and it seemed to burn really clean and it made it tough to read what was going on. now i am using 93 octane amoco fuel and i get a reading. with this fuel, i know how i like my plug to look like for best performance. i probally jet my bike a tad bit lean, but that is how i get the best power.


if your plug is coming up black, i think your either rich or have an air leak. does the bike seem to run fine? if your plug is black at idle, your probally rich on your pilot/fuel skrew given that everything else is in good working condition. try to turn your fuel skrew too two turns out from lightly seated. check the plug again after letting it idle for a min or two.

i honestly don't see how your 100% sure your needle is in the right location? i am not saying your wrong because i don't use dynojets though.

[sprtrx300ex]

The reason I have a 42 pilot in it is becuase it it usually around 30 degrees this time of year, but for the past few days its been warmer. I have the 42 for the winter weather thats coming.

About the needle position,
I tried the clip on the 4th notch, and it started blurbering and stumbling. So I put it on the 5th notch. It got alot worse. So I put it on the 3rd and it runs great with NO blubbering or any studdering.

Anyone think that a 146 main is too small? I have heard of people running 130 main which im sure is way too lean, and Rico has a 146 and hes got a 416. I have also heard of people running up to a 165 with a setup like mine. So, anyone have an idea?

[cals400ex]

Originally posted by sprtrx300ex
The reason I have a 42 pilot in it is becuase it it usually around 30 degrees this time of year, but for the past few days its been warmer. I have the 42 for the winter weather thats coming.

About the needle position,
I tried the clip on the 4th notch, and it started blurbering and stumbling. So I put it on the 5th notch. It got alot worse. So I put it on the 3rd and it runs great with NO blubbering or any studdering.

Anyone think that a 146 main is too small? I have heard of people running 130 main which im sure is way too lean, and Rico has a 146 and hes got a 416. I have also heard of people running up to a 165 with a setup like mine. So, anyone have an idea?


take it out at full throttle and shut it off and check the plug. see what it looks like. i have been told that a 146 is only one size bigger than the stock keihin 148.

[chrisc]

I don't know if it will help but I just put a dg jet kit in mine and have a e series with a K&N I set it just like they said , 3rd notch with 146jet and also the 42 pilot . and 3 1/2 on the air screw . it ran way too rich so had to turn it down to around 2 1/4 out and it runs great

[sprtrx300ex]

Alright I'll try that. Thanks guys

[WhiteBros400ex]

i have dyno and i have a uni air filter and white brother e series and i run a 160 and it runs fine not to rich or to lean i tried the 146 and it ran lean so i say go up .if u got ne problems PM me

[sprtrx300ex]

Alright! I was think that the 146 was a tad lean, but theres not a 150 main in the kit :mad: , I'll try a 155.

thanks

[cals400ex]

Originally posted by sprtrx300ex
Alright! I was think that the 146 was a tad lean, but theres not a 150 main in the kit :mad: , I'll try a 155.

thanks


talk to "ewalker" on this site. i believe after a few emails, they sent him a 150.

[cals400ex]

by the way, putting in a larger mainjet is not going to fix your black spark plug. i have a feeing your too far out on the fuel skrew. you may also be a tad rich on the needle.

[sprtrx300ex]

I think that the fuel screw might be a little rich. How many turns out should I set it?

[cals400ex]

if your just running a slip on and the filter, i would try around 2 turns out with a 42 pilot. now that is just a guess. i know i am only 2 turns out with my 42 pilot on my built motor. however, building the motor didn't actually change jetting that much for me.

[sprtrx300ex]

Alright thanks! I'm gonna mess with it tomarrow.

[sprtrx300ex]

**UPDATE**

Today I went out and started it. Its about 50 degrees outside. I put the choke on half and tried to start it. It didnt start, I pumped the throttle once, and it didnt start. I pumped it again and it fired up. It poped and cracked real loud and shot out some smoke(grey puffs). I just shut it off.

Im running the 42 pilot w/ 1.75 turns out on the fuel screw.

however, yesterday it was about 70 degrees. It started up fine and quick with no popping.

What do you think the problem is? It has done this before when I tried to start it.

[sprtrx300ex]

bump

Anyone???

[TravEX]

they are just "cold natured",,,i would rather take a kick to the sack than try to start mine if it's below freezing outside! :p hehe

[cals400ex]

for the colder months, i would leave it at 2 full turns out. i usually find mine to start easiest with full choke even when i have the 42 pilot in. yes, these bikes are cold blooded. by the way, did turning the fuel skrew in fix your black plug?

[sprtrx300ex]

I have not had a chance to get another plug yet. I plan on gett ing one today to do the test.

[JOEX]

When starting cold pump the throttle 4-5 times then hit the start button;)

Joe

[Samson]

I just pulled a stock 146 out of mine and the DJ's run small. The DJ 146 is smaller than the Keihin, I think. I know that's the way it work with the larger sizes. I'm running a 165 DJ main. I'm pretty sure that's the equivalent of a 155 or so Keihin. I found a sizing chart one time, but didn't have any luck finding it again today. I think your're lean.

[sprtrx300ex]

I thought that DJ sized up to be bigger than keihins :confused:

[Samson]

I'll try to find the chart again, but come on, why else would you have a 170 in the DJ kit? By Keihin's sizes, nobody could go that large. I think the 170 DJ was about a 160 Keihin. Let me see what I can find! :)

[cals400ex]

Originally posted by Samson
I'll try to find the chart again, but come on, why else would you have a 170 in the DJ kit? By Keihin's sizes, nobody could go that large. I think the 170 DJ was about a 160 Keihin. Let me see what I can find! :)


i have been told that the dynojet 142 is about the same as the keihin 148. so, dynojets are a little larger from what i have been told. i guarantee i would be able to tell how the sizing compares if i had a dynojet kit. i read my plug all the time. but, i don't have a kit so i can't tell you. by the way, many people run a 170 keihin jet. i have seen people run a 175 with just a slip on silencer. however, they are too rich. also, dynojet may tell you to run bigger jets than is needed so your bike runs a tad rich. this will make your bike run cooler and then they won't have any problems with people overheating their bikes due to lean jetting recomendations.

[Samson]

Originally posted by cals400ex
i have been told that the dynojet 142 is about the same as the keihin 148. so, dynojets are a little larger from what i have been told. i guarantee i would be able to tell how the sizing compares if i had a dynojet kit. i read my plug all the time. but, i don't have a kit so i can't tell you. by the way, many people run a 170 keihin jet. i have seen people run a 175 with just a slip on silencer. however, they are too rich. also, dynojet may tell you to run bigger jets than is needed so your bike runs a tad rich. this will make your bike run cooler and then they won't have any problems with people overheating their bikes due to lean jetting recomendations.

I've been told anywhere from a 142 and 158 Kehein with pipe and filter for my elevation. That's why I bought the kit. Wanted to take some of the guess work out.

I'm sitting here looking at the 142 DJ versus the stock 146 and I can see that the DJ is smaller. It's not even close.

[sprtrx300ex]

I believe stock is a K148. Do you think running a 155 would be too rich? Thats the next closest size I have. I've been have problems with my plug being black, and I think its from the fuel screw. Tomarrow I'll adjust the carb to 2 turns out on the fuel screw and put in ....the 155??? or leave the 146?

[Samson]

With a pipe, filter, no lid or vented lid, under 3000 feet...DJ recommends the 170. So no, I don't think the 155 would be too rich, but buy a new plug & check it after some riding time.

ps - I must've enhaled too many fumes because stock K148 is right! Had to go back and look again.

[sprtrx300ex]

Alright I'll put in the 155 and try it out. I appricaiate all your help guys.

Also, I put te choke on full, and it starts right up. That all I need to do to start it.

However, a few puffs of black smoke come out when I rev it. Its only when Im starting it up tho. Any ideas?

[Samson]

I'm really wondering if you should try putting the stock pilot jet back in???? :confused:

[sprtrx300ex]

I dont think I should, since winter is coming. However, I might go down to a 40. I will deffinitly go to a 40 when it warms up.

[cals400ex]

i run a 42 pilot in the summer and winter months. however, this summer i may try a 40 pilot if i can't get it to lean out enough by using the fuel skrew. however, the fuel skrew is usually has enough adjustment for me to run a good air/fuel ratio through out the year at idle.

[sprtrx300ex]

HOw many turns do you run in the summer?

[cals400ex]

Originally posted by sprtrx300ex
HOw many turns do you run in the summer?

i am not positive on this, but i think you are suppose to run the fuel skrew between 1 and 3 turns out. if you need to go less than one, get a smaller pilot. if you need to go more than 3, get a larger pilot. i actually don't remember where i leave it in the summer. i would imagine that it would be close to 1.5 or so with the 42 pilot. i may have to even pop in my 40 pilot in the summer months. i will have to see when the time comes. last summer, i didn't have my cam and piston yet so that changed the jetting a little bit, but not much. also, i use to run no airbox lid but now i run with the lid on. this will also change jetting.