2001 YZ426 hard starting

Shes having a hard time starting. This is what I have done sor far: Replaced gas, cleaned carb, replaced plug. Checked coil .4-.5 ohms. Sometimes she starts, sometimes she don't. Floods easily. Could it be a weak coil? Is that common? :p

Maybe you could use a Valve adjustment?

Valves are all within specs. Any other ideas?

Whens the last time you replaced/cleaned your air filter?

Also check your timing, all it takes is being one tooth out. Hope this helps

Shes having a hard time starting. This is what I have done sor far: Replaced gas, cleaned carb, replaced plug. Checked coil .4-.5 ohms. Sometimes she starts, sometimes she don't. Floods easily. Could it be a weak coil? Is that common? :p

Manual says primary coil resistance should be 0.2-0.3 ohms at 68F.

I believe colder the temperature the lower the resistance. So if its less than 68F in Maryland then your resistance would be even higher than the measured0.4-0.5 ohms if it were 68F, so maybe its a bad coil.

That being said, the stock AP setting squirts fuel for about 3-5 seconds (mine was around 4-5 range) so they flood easily. After I did the BK mod it doesn't flood so easily and is easier to start. When you start it cold, prime with a couple twists of the throttle, then hold onto the brake reservoir or any part of the handlebar other than the throttle so you don't give it any more gas while kicking it.

I would make sure you have a new cr8e plug and do the correct starting ritual. If that fails, then think about a new coil.

Air cleaner is clean. I checked the coil in 70 deg weather. Check connections/ resistance and still won't run. Its sparking, but SEEMS weak?

i belive the pilot screw should be 1 3/8 turns out on the 426's. i had the same problem with my 400 flooding out.

Is your compression stroke still hard as a rock? If not your timing may be off one or two teeth. My 01 started and ran ok until I jumped the timing chain some additional teeth. The guy I bought my 426 from told me he thought the bike had a auto decomp cam because the compression stroke never got rock hard. He ran the bike with the timing off recreationally for a year -changing plugs & constantly messing with carb. It was the timing the whole time. Turns out we both had no clue. The price of being a newbie:doh:

^^ As in rock hard as its impossible to push it through, or just that you know you have hit it?

Ex: It hurts if you try to give it a kick before its ready, but if you push hard it will go around, because thats how my bike is.

Also with the weak spark, is the coil ground attached to bare metal frame? (I had the coil unbolted from my bike to set sag, I forgot to bolt it back on and was kicking it for 5 minutes before I realized it needs to be bolted back on, fired first kick. LOL)

I ended up checking all the resistance per Yamaha manual. The coil was on target, but the magneto #1 coil was .832 ohms (should be 700-1200 ohms). I belive its shot. #2 coil was 53 ohms (which is right). Ordered a new magneto and the old one was burned up, and should get it next week. Thanks guys for all your input! Keep you posted....

I also believed my stator was dead, until I checked it, and found out that a previous owner mounted an E-Line stator :):banghead: :banghead: :foul:

My bad, the magneto was good after all. I took it to work and had a EE look at it. I did check the ohms from coil to spark plug and noticed the new coil read 128 M ohms and the old 23 M ohms. I will put it together and try it....weird!

Sounds like a problem with your meter. Coil primary resistance is supposed to be .2-.3 Ω, and the secondary resistance should be 9.5 - 14.3 KΩ. even 1 MΩ is 66 times higher than it should be at the least.

Try again.

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