04 yz450 starting help

a friend of mine has an 04 yz 450 that is hard to start when it is cold. once its warmed up it never takes more than 2 kicks even when its hot.

when the bike is cold it may take 20 - 50 kicks to get it started. we have pulled the plug and it is pretty wet. he isnt giving it any throttle at all, and usually after changing the plug it will fire up within a couple of kicks.

any advice would be appreciatied.

Do a search on the subject. There have been a number of threads in the past couple of days regarding starting big yamaha 4-strokes. Lots of advice.

However, the main thing that was required to get my 426 start easy everytime was to clean the carb/idle circut (jet). It got gummed up a bit and was a bi-yatch to start. Changing plugs worked for a while, but then it just wouldn't start at all. Now that it's cleaned, it fires up super easy everytime.

I also recommend having your friend drain the float bowl after each day of riding...even if the bike will only sit for a few days. That should keep the carb/idle jet clear and eliminate future problems of the same variety.


Jeremiah may be right, but to me it sounds like a valve issue. When cold starting is IMPOSSIBLE :) and hot starting is 1-3 kicks (easy) :) , thats usually a sign of tight valves. Please report back when you find out what it is, im curious... Good Luck

Y6R...that's a good point. I'm just glad my carb clean cleared up my issue.

I had the same problem on my 04. I don't get to ride very much, so I'd have to let it sit for a while and then when I went to start it, I'd end up kicking my brains out.

I have it down to a science now. Always starts within 3 kicks when cold and one when hot.

What did I do?

Just find TDC (top dead center) before kicking it over. Slowly nudge the kickstarter until it comes to a hard spot. That's TDC. Then let the kickstarter return all the way to the top and kick away. It should fire right away.

I went through so much headache before doing this - fouling plugs, etc.

It could also be valves, but Yamaha valves rarely go out.

Try this and see if it works for you too.

I found out by accident the best way to start mine. It's a 2004 WR 450 as well. Here goes: It was really cold out, snow on the ground. I thought I'd try something different. I pulled the hot start lever and kicked it three times. Nothing. Then I looked down, oops, left the gas off. OK, gas on, cold start lever out, kicked it three more times, nothing. Oops, duh, ignition off. Turned on the ignition and it fired up on the first kick, I mean really fired up! Started thinking. Here's what happened. Hot start lever kicking with no gas on....cleared the cylinder. Gas on and cold start lever out with no ignition....primed the cylinder with fresh gas (just like my airplane). Ignition on and it had no choice but to start. Tried it since only with the magic button after the ignition is on and whammo, starts up with just a bump.

BTW, I only kick off top dead center on compression stroke, doesn't everyone?

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