Hard to start now that its cold, and plug color


You crack me up! This is the first time my bike has had trouble in winter. When I studied jetting q's I paid attention to the ratio of the fuel to air jets. That is how I arrived at what I had. The other thing I noticed is that many (not all) of those who like larger jets also had the open pipes.

Since you and I use the same pipe, I'm taking the plunge!

To settle this once and for all, I'm going as close as I can get to your jetting with the components I have. I've already got it installed, just need time to ride. I have the following needles, EKQ, EMP and EMN. I currently have the EKQ installed, so I'll test it first. Then onto the EMN, I'll try c-4 first.

The main is 150mj/160maj

I don't have the 35Pj, but I do have the 38, so I put in the 38 with 65paj. It starts well.


Nice work amigo! Glad you "switched" from the dark side and are taking up my jetting! Tell me what you think when you get a few rides in under your belt. Might want to go up a tad on that main jet though...especially in the winter. Also, never got that 35PJ to work very well for me...the 38PJ/65PAJ seemed to work the best with the __P needle (Denver tracks, Rampart, and Moab) and the __Q needle over 10K ft (St. Mary's, Crested Butte, etc.). Finally, I found the __N needle was a bit too rich for our altitude. See my sig for specifics on what I found to work the best...these are "summer" setups, so use the higher end of the main jet range in my sig and you'll be good to go.

QUESTION...why are you worrying about jetting your bike when 40"+ have fallen in the past 3 days in Steamboat?!?!? There's only one thing on my mind now...and that's getting tracks in the deep freshies up there!

Late amigo

Hey Steve,

How is this jetting working for you now that you have switched? Where did you get the needles? Somewhere in Loveland or Fort Collins?

I rode the annual Zekes ride from Cheyenne Mountain Zoo up to Victor at 11,400 feet yesterday (New Years Day) and fouled a plug halfway up. It was damned cold to say the least! The cylinder was luke warm at best and the plug was not even hot when I took it out of the bike. I put in a fresh one, rode slow, got to Victor and stuffed quite a bit of paper towels between my radiator guards and radiators and made the rest of the ride.

I'm going to finally tear into my bike and do some jetting updates so let me know what you end up with. I may still need help with the BK mod as well.



Hey John,

I got all my stuff from Sudco. Do a search for that name and you will find one post with a 1-800 number for them. I got it all installed, starting with the EKQ-4 needle setting. Around the neighborhood it runs pretty good, some sputtering at about 1/2 throttle though.

Current settings: 38/65 150/160. I also have needles EMN and EKP.

I'm planning on testing at Berthoud on Saturday if weather is good. Let me know if you want to come. If the weather stinks, it would be a good day to BK, just gimme a call.


My WR426, my friends 426, and my DRZ400e all start poorly at 35-40 degrees and colder. In spite of all that is said about NOT using the throttle to start these bikes in the cold, this is what we have found. First if the bike has sat for a while, turn the gas on early if possible and leaning the bike to the left until the gas flows from the carb is a good idea, though I have don't do this.

Now comes the part you won't believe... CHOKE IT... and twist the throttle at least 3 to 5 times (1/2 turn is all thats needed)and kick it over 3 to 5 times. Mine will normally start with the first priming of 3/5 throttle flips and then die. Now turn the throttle 5 to 10 times and kick it over til it starts and dies again. Do the 5/10 twists again and again until the choke kicks in and the bike runs as it should using the choke. I usually have the bike running in 4 kicking sessions or less. If you try this and it does or doesn't work maybe you could post your results to see if this is or isn't a way that 4 strokes can be started when its pretty cold out. It has worked for me at 15 degrees but it took a few more kicks, and thinner oil would have helped.

Hey Steve,

I looked up the BK mod and it looks pretty simple so I think I can do it myself.

I'm going to search through the jetting archives before I do anything. From everything I'm reading, I'm way too rich on the Main Fuel Jet, the stock needle sucks, my Main Air Jet is too large, etc.

I bought this bike from a guy who put 250 miles on it. Fort Collins Motorsports set this thing up for him which leaves me little confidence that this carb is set up correctly.

I'm not sure about doing anything this weekend. I was gone so long yesterday that I owe my wife a little break for letting me ride on New Years day.


Hey Jim,

You starting procedure sounds exactly like mine. With the exception that I dont give it quite as much gas. Im a little gun shy of flooding it. I hate changing plugs in 20deg weather. It takes me a few more tries to start it. But it usually starts. Mine also does the start and die routine a few times b4 it starts to idle.

I tried to start it the other day without laying it over and it wouldn't even sputter. Once I layed it over and let it drool it started to make some noise.

Jim I know what your saying.That works for me too.

When its starts for a second and dies you have to give a handfull of twists to get it primed and it will start.

I was out on the 27th and I had my WR running in about 6 kicks and it was -4 C. Took a while to get it warmed up though.

I changed the spark plug before I re-jetted. Since then, I've started the bike about 10 times, and it is reliably starting on kick 1 to 3 with the choke on, and no twisting of the throttle. It hasn't been too cold lately, so we'll see if it holds up when temps dip.

Its start easily after I changed out the plug, and continues to with the re-jet.

I'll read the plug color after testing this wknd.

Jim, I have tried twisting the throttle as you mention. I'm curious, have you done the BK? If so what duration are you using? I've got mine set to a very slight squirt <.5sec.


I used to tip all my two stroke bikes to fill the carb bowl if they had set for more than a day or two. Doing it on a four stroke helps guarantee that the bowl is near full and the carb will start functioning quicker.

>Somebody must have something on my original question, anyone????

Yes, I still get tan plugs in the winter, however, I have to run race gas instead of the

crappy oxy fuel we have to burn during the winter. There are 3 of us, on the

same bike ('01 YZ426F) that have to do exactly the same. When we don't run

race gas, we all foul plugs during cold weather. I can put a new plug in the bike,

runs great all day, but when I try to restart the next day, it'll foul. It only does this

during cold weather. We all started running race gas and the problems went away.

Two other notes:

1) If it's been a couple of weeks since it was started, I drain the fuel bowl before

I try to start it. It seems to help.

2) I've had a couple of scenarios where I had to crack the throttle slightly to get it

to light. One of those days I'd been kicking for almost an hour. I cracked the

throttle slightly, and held it there, and it fired right up. I don't recommend this

unless you're really familiar with the bike and it might backfire when you do this!

Bottom line? Ditch the oxy fuel in the winter and ante' up for some race gas.


Hey Steve,

Did you test yesterday? Let me know your results and let me know what your settings are.


Here are some results so lets see what we can make of this

I left all the jets the same as above and just varied the needle since the jets I have work for many people.

EKQ-1, Sputtery and misfiring a lot, Plug is WHITE with dry black around botton of threaded part.

EKQ-4 and new plug, less sputtery, power pretty good, but a bit anemic at mid. Plug still white with black ring.

EMP-4 and new plug. Much better power across the board! Plug still white and black ring. Can feel small power increase when I transition off the needle.

Since the plug is white, I guess it's still too lean. Should I go up on the main, or to the EMN? Am I paying too much attention to the plug color? I just don't want to run it too hot.


You're almost there bro! Your EMP#4 is the same as my EKP#3 listed below in my "sig" (for lower than 10K ft riding).

I suggest you should put in a 38PJ/65PAJ combo with that same needle. I think you'll find that the bike will be a lot snappier off idle. Try it, you'll like it! Also, I think you'll find that the EKN (or EMN) needle will prove to be too rich...I tried it and it sucked...stuck with the E_P needle. Another point, if you ride over 10K ft, you WILL foul your plug by using the E_P needle...switch to an E_Q needle and lower the main and you'll be good to go (see below).

RE: plug color...I'm in the camp of "it doesnt really matter"...since rich jetting in one throttle range and be disguised by lean jetting in another throttle range. Do it by feel of the bike instead (vibrations, sluggishness).

Let me know how it turns out!



I agree with larryco on this one. The jetting in my sig consistently gives me a white plug, but I have plenty of power, and no harsh decel popping or backfires,

When I was in texas I had a jetting conversation with a racer in the area, he seemed real lost, but I went to posi 4 and a 162 main and had no problems all day. all air jets and needles are still stock in my bike.

Maybe I ought to go out to berthoud with you guys sometime. Maybe my bike isn't as strong as i think it is??



I haven't updated my sig yet, but the results I posted above are with your and Taffy's jetting: 38/65 and 150/160! I am thinking this is where it will stay. The bike ran great.

When you or racemile want to come up to Berthoud let me know. There are some big straights where we can test WFO in 5th and more than just the one track you see from the hiway.


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