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Glen Wallace

Runs with choke on and unusual starting sequence

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I have a 2001 yz250f and got it in pieces. It's my first 4 stroke but I've got it running, just. 

I'll start with the starting procedure;

Turn the fuel on

Choke in or out, doesn't make a difference 

Turn the idle knob way down

Hold the decompressor level in and kick it about 5 times.

Then kick it and it'll fire, then I have to hold the throttle on a bit to hear a nice idle speed while winding the idle knob up to match it.

Now at idle and no choke it has a bad hanging idle if i touch the throttle. But if the choke is out there's no hanging idle.

Now if it's fully warmed up i can't start it no matter what I try.

Any thoughts would be awesome guys and gals.

 

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Air leak! Or running lean. I have an 01 yz250f once I got it dialed it’s starts 1-2 kicks cold. When was the last time you checked your valves? Also how is your cam chain and timing?

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Air leak was my first thought so and noticed the intake manifold was a bit sad so I replaced it but didn't help. I haven't checked the value clearances, waiting on tapered feeler gauges in the mail. I did notice the cam dots wouldn't line up perfectly though. Need cam chain time? I'll keep y'all updated until the to help others with the same problem. Also the carb slider wheels have worn a bit into on side of the carb housing. Is she a mess or what!?

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Air leak was my first thought so and noticed the intake manifold was a bit sad so I replaced it but didn't help. I haven't checked the value clearances, waiting on tapered feeler gauges in the mail. I did notice the cam dots wouldn't line up perfectly though. Need cam chain time? I'll keep y'all updated until the to help others with the same problem. Also the carb slider wheels have worn a bit into on side of the carb housing. Is she a mess or what!?

Worn cam chain can cause lots of problems. Worn carb slider could cause hang idle. Once you get it figured out it’s a really good bike but it’s a pig good for desert riding and a blast on the track.

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I have a all balls carb kit coming in the mail but I'll order a cam chain and maybe shims when I get my tapered feeler gauges to measure the valve clearances. Stay tuned😁

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Alright! I fix the hanging idle woop woop. There was a extra oring still in the air fuel mixture housing even though I removed one lol also i cleaned the jets hardcore. And after that it wouldn't fire at all. Checked the plug and it was fouled. So I changed the plug and leaned it out and it now returns to idle.

But it's not over yet. The starting sequence is still the same. It will only start with the idle down all the way and priming it with a few decompression kicks. Once started i have to rev it while turning the idle up to where it should be. Any thoughts would be amazing guys

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Your right Four Square, the intake clearances are ridiculously out of spec. The timing dots on the cams actually line up pefectly now which is good. I'll get shimming!

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