2001 Yamaha 426

My 01 426F wont start. Here recently, its blown 3 different spark plugs. I thought maybe a coincidence, however, everyone else Ive talked to says it shouldnt be doing that. Thought maybe it was getting to hot, coolant checked fine. Now, after about 4 months of setting, it wont start. When i parked it, it didnt start and was tired of kicking it. It has spark because I put a new plug in it and made sure. When i bought it off the a friend, there was some issues with what i would guess be the idle adjustment. Half a turn one way or the other and it wouldnt start. However, it was never this bad. I could ususally get it started within 3 or 4 kicks. Now, nothing. Dont know if I should look into it deeper, or take it to a shop. Any info would greatly be appriciated. Kinda new to the motorcross thing, always rode 4 wheelers till i threw a leg over a 426F, now I would just like to get it running the way it should be. Thanks

What do you mean by blown spark plugs? If they are getting fried, then there may be a priblem with the ignition. If fouled, its jetting /air/fuel

Overall the 426 is a solid bike. Some of them were finiky with spark plugs. Search here and you'll see many threads about it. For me making sure it fully warmed up before shutting it off eliminated all of my spark plug issues. Search here and you'll get gobs of info. Once you've got the drill right, if it wont fire after a handful of kicks then switch the spark plug before you do anything else.

Not sure what you mean by "blown" sparkplugs. But the first thing that I would do is drain all of the fuel out and replace it (premium pump gas at the minimum) and make sure you drain the carb at the same time.

Then I'd check the valve clearances. The 426 can be hard to start, especially when cold, if the valves are too tight.

Make sure you are following the recommended starting proceedure (watch the videos). I know that if I even touch the throttle on my '00 426, it won't start.

Thanks Fellas. I am going to try these things this weekend. As for the starting procedure, Ive been doing it correctly. When I first got the bike, I could start it within 1 or 2 kicks. As for the spark plug issues that ive been having, its been blowing spark plugs. What I mean by that is the past three spark plugs have had the isulator cracked down inside the plug. It wasnt sparking at the very end, it was down inside the sparkplug. The only thing I can figure out is that its cracked the insulator and it sparks down inside the plug, rather at the very end. The only way i found it was by turning out the lights in my shop and having a buddy help kick it. Once it gets cracked, i cant get the bike to start at all, as you can imagine. The end of the plug doesnt have any damage, so that in my opinion eliminates mechanical impact. I am lost....dont know where to go. Maybe not enough oil getting up around the piston making it to hot? Antifreeze checked fine. I really dont know, just wondered if anyone else has had this issue, or if I am the one and only lucky fella out there. Thanks again for all your help, going to try all your reccomendations this weekend.

Thanks Fellas. I am going to try these things this weekend. As for the starting procedure, Ive been doing it correctly. When I first got the bike, I could start it within 1 or 2 kicks. As for the spark plug issues that ive been having, its been blowing spark plugs. What I mean by that is the past three spark plugs have had the isulator cracked down inside the plug. It wasnt sparking at the very end, it was down inside the sparkplug. The only thing I can figure out is that its cracked the insulator and it sparks down inside the plug, rather at the very end. The only way i found it was by turning out the lights in my shop and having a buddy help kick it. Once it gets cracked, i cant get the bike to start at all, as you can imagine. The end of the plug doesnt have any damage, so that in my opinion eliminates mechanical impact. I am lost....dont know where to go. Maybe not enough oil getting up around the piston making it to hot? Antifreeze checked fine. I really dont know, just wondered if anyone else has had this issue, or if I am the one and only lucky fella out there. Thanks again for all your help, going to try all your reccomendations this weekend.

What color is the plug burning? The insulator should be light tan...should have little carbon on the tip. Otherwise, it sounds like you're breaking the plug when gapping it maybe?

What I mean by that is the past three spark plugs have had the isulator cracked down inside the plug. It wasnt sparking at the very end, it was down inside the sparkplug. The only thing I can figure out is that its cracked the insulator and it sparks down inside the plug, rather at the very end.
10:1 there's no crack. That is what a fouled plug acts like; the spark energy is shorted along the deposits on the plug insulator.

Are you using CR8E plugs?

I always thought that a fouled plug was meaning to much deposit on the end of the plug where the spark is. What can be causing this fouled plug, exspecially 3 in a row. As far as what kind I am using, i didnt really pay to much attention to when i bought them. However, i did buy them from a deticated Local yamaha shop, and I would hope that they would give me the right plug. I will check on that to find out just which plug I have. Sounds like Grayracer is the Yamaha guy around here, I appriciate everyones help around here.

As crazy as it sounds, check your valves. Mine started to foul plugs and it ended up having a tight center intake valve. I adjusted the valve and the problem went away.

Checking valves is a good idea, overly tight valves will definitely affect starting and low speed performance. If left too tight for too long it could affect performance everywhere and potentially burn the valve or the valve seat requiring some work to get it fixed.

As for fouling; a fouled spark plug is basically a plug that won't spark because it's got goop on it. Sometimes it's piles of stuff caked up, or in the case of these 4-strokes it's commonly just wet fouled, which means there's something wet and conductive on it (fuel, oil, etc..) and it's shorting the electricity. So instead of a spark jumping, the electricity just goes through the goop. In the case of a wet fouled plug, you can often save them by hosing it off really good with carb cleaner. Be sure to use the spray tube and spray down around the insulator. Blow it dry before putting it back in the bike.

Your stator could be going out. The manual tells you how to test it. A friend of mine's 00 426 started going through plugs and then wouldn't start at all. Once he replaced the stator it starts great.

I moved to Alaska from Colorado in May of 07 taking my YZ 426 on the 4000 mile journey. I tried to start my bike but had no luck. It always starts on one or two kicks. No spark was present with new plug. After several frustrating days of wiring,etc I removed the ignition timing plug only to find motor oil running out of the hole. Apparantly during the move the oil from the tank had worked it's way down to the stator and flooded it.

I simply drained all the oil from the bike,added new filter and oil ,checked for spark which now looked very stong.

The YZ now started on the first kick.

Good ridin.:busted::banghead:

Oil in or around the stator is there by design, and will not cause the problem.

True the stator does run in oil. But not to the point of being totaly submerged in oil that leaked down from the frame tank . Any way it worked in my case.

Every time that you leave the bike sit for a week or more, the tank will drain to the crankcases, and the stator will be submerged. Are you then going to drain and refill the oil each time? In '03 and later models, the oil is filled directly on top of the stator when refilling after an oil change. How do you propose to get around that?

The stator is intended to run in oil, and is not in any way affected by it. I suggest to you that what happened to yours was entirely coincidental.

True the stator does run in oil. But not to the point of being totaly submerged in oil that leaked down from the frame tank . Any way it worked in my case.

The stator on the YZF's are designed to be in the oil. You probably have a loose connection somewhere. :banghead:

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