Hard to start now that its cold, and plug color

Since the onset of the cold, it's been really tough to start. Also, it runs pretty sputtery while warming up, occaisionally while riding it. Changing the plug helps for a while (CR8E). But, I've noticed, the plug is always black and has never been the tannish color that 4 strokes should have. Do most people get the tannish plug color? If so, does anyone see anything in my jetting specs that might be causing this problem? If not, what else could I do to get the plug color right?


I just asked a similiar question on this also on a another thread. I just change my factory plug for a couple of reasons, one I needed to do a oil change and second I was curious to see the color of the plug. Its been 400+ miles on it and I was having aa very hard starting it this past Saturday, so I thought why not. On my XR400 I enjoyed showing the plug off to the other guys because it was ideal in color and I would only change it once a year.

On the WR426 it was very black and had corrosion on the top of the ring on the plug. It looks like salt corrosion. Anybody else see this?

So, Yes I did change it to a CR8E fired on the first kick and no problem, but I too would be interested to know what others have seen on the color of their plugs. :)


I've gotten the answer to the salty looking corrosion problem you mention. It comes from water that gets down in the plug hole when you wash the bike. If you want to see another place where similar corriosion occurs, take off your kickstarter and look inside the part that rotates. If you do, watch for the spring-loaded ball bearing in there. I took mine apart and it was loaded with the corrosive looking crud.

So, does anyone get nice tan plugs?

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

I understand plug reading is not the same mowadays because of all the additives they put in gas.

My stock jetted 2000wr's 1 yr old plug was clean with a light redish color on the insulator. Otherwise clean.

I suspect a black sooty fould plug means yr bike is running rich.

check yr jetting an consider leaning it out.

Is the insulator is black, drop the main and or needle.

If the outer ring is black, turn screw in or drop the pilot jet.

Also, make sure the air filter is clean.

A black plug in No good.

Hey stefe999

I just went ridding yesterday in about 25-30 deg weather. My 400 starts hard in the winter also. About the only thing that I can suggest is to lay the bike over on its side b4 you try to start it. Keep it there until gas starts to drool out of the carb vent tubes. I tried to start it without doing that yesterday and it diddn't even pop. Once I layed it over it started to sputter. Usually it starts and stalls. It does this about 10x b4 it stays running. Its a pain but it will usually start. Also let it idle for a long time and get really warm. If I take off too soon it will start popping and coughing.

If it is still poping when your ridding. Try putting duct tape over the radiator shields to keep the air out. Sometimes its so cold out that the air cools the bike faster than the engine can heat it. The tape helps.

Change your oil to 10-40 and give it a couple of more twists of the throtle befor kicking. Works for me.

Cold starting is a pig. I went from 1-2 kicks in summer to not being able to start the darn thing. I figured out I have to give mine quite a bit more juice than normal during the starting prodedure, otherwise it won't fire up.

I normally only gave a very small twist of the throttle to prime the carb, but in the cold weather I give it a full twist and a tad more. It starts on kick 5-6 kicks then dies then starts again 3-4 kicks later. It doesnt tick over too well with the choke on unless I blip the throttle slightly. It then runs fast and after about 5 seconds I turn the choke off, and it settles donw to idle speed. I then let it warm up real good before riding.

Weird......I can leave my bike for weeks at a time.....and it still starts first kick from cold...leave it on choke for about 1 minute then it's OK.......perfectly rideable and the plug is a light gray colour, summer/winter up hill down hill, it's always gray !

I'm on a DTM clip 3 and 160 MJ 160 MAJ :)

Stefe,try going down a size or more with the pilot,when the plug get`s fould up starting is a bit like you say,maybe try a new plug just to start it,if it fire`s you know it`s the plug.I have the same bike and i suspect the pilot circut is too rich on a 42,and over time it fouls the plug,i`m now waiting for an adjustable pilot air jet so i can try to eliminate this!,take the tank off put in a new plug start it up and let it idle a little then take the plug out and have a look,if it`s all sooty,pilot is too rich!,remember be carefull with the plug threads on a hot engine,they damage easy,if in doubt let it cool a little

I'm afraid that if you follow captain_S's advice you will make your problem worse.

When it gets colder your bike will run leaner. But a cold start requires a rich mixture. Thus it makes sense that the bike is harder to start when cold UNLESS you have richened the pilot circuit. I would guess that you are also getting some popping on decel too - also indicative of a lean pilot circuit.

Have you tried to simply adjust the fuel screw OUT? I would try about a 1/2 turn first. If you end up more than 2.75 turns out put in a larger pilot (not smaller!).

Sound`s to me that a spent plug is why it won`t run good,and my wallet tell`s me spent plug alway`s black,that`s why a fresh plug help`s you when you are out riding,then it fouls and you back too square one!,it will not start with a spent plug in the cold no matter how rich you make it!remember only you can set the carb for how you ride!

When I took out the plug, it was wet so I definitely had fouled it. The plug had only 2 short rides on it, so if it was spent, it was premature. Because the plug was black I thought the pilot ckt. must be rich. But, as captian S says, with Winter, if it was rich, it would be leaner now. So before fiddling with the pilot ckt, I will try adjusting the fuel screw. I know that the FS is used to set the idle, but can someone explain what its affect other than that is.

Yeah, the FS adjusts the idle fuel mixture and also affects low throttle opening. Make sure your engine runs warm enough. Try covering part of your rads (below 50*F). Have you switched to 10W40 oil?

EKQ pos#1? Just a guess; maybe you are lean on needle and trying to compensate with pilot..?

I am running the 10W40 oil now. We'll see how it behaves this weekend.

stefe9999 is the 9999 for the emergency services, dam that's over here, i forgot. for a moment i thought it was stefe(i'm always in trouble dial 999 for the jetting mobile). so you learnt nothing in 18 months of JQ?

i give up.

it's nobody's job on this web site to say what the laws of physics are. not one of you knows all the facts.

so i offer this challenge.

if you know all the facts and you can put them all up here then do it. but if you think you know just carry on as you are.

every autumn you guys flood and every year i don't have a problem, the difference is that i deal with things as i find them.

your way over jetted but did i teach you anything new there stefe?

thought not.



I stress the importance of operating engine at a warm enough temperature by covering part of rads at cooler temps before determining what is wrong with jetting. Simply feeling the engine by touch should indicate this as there is no thermostat to control cooling.

Laws of physics never cease to exist here and I have never fouled my plug, by the way.(2800 miles on a CR8EK) :) ...and don't worry about my big MFJ, I am switching to an EKN with smaller MFJ...


With your signature jetting, what elevation and temperature were you at? As it got colder what changes if any did you make? Thank you.

I'm not having any problems with plug fouling....


Bonzai :)


What Taffy is telling you is that as the temp. drops you need to go leaner on jetting. Yamakaze will also say go leaner. You will get conflicting opinions on this subject. If the plug is black & sooty its to rich, this is a common fall problem. I think this is what Taffy said. The English wit is at times hard to understand. If you have a beer or two beforehand it will make more sense.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now