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Idle problems for '05 YZ 250

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Recently my bike will not stay at idle. I had it to where it would idle for 5-8 seconds then die. When I adjust the idle screw and the air screw it does nothing with the idle at all. The bike runs perfect from bottom to top, no hesitation or boy anywhere. The only thing I can think that made a difference is that I added boyesen pro series reeds and a PC 304 standard lenth silencer(both at the same time). The idling issue did start after this. I'm riding at sea level in the mid 80s(south Louisiana). Didn't ride much during the winter but the jetting is the same as last summer. The bike is bone stock except for the reeds and silencer. Stop pipe. 93 pump gas. 50:1 ratio. Hope that is all the info ya'll would need.

Any help would be appreciated.

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If it's any help, I just added boyesen reeds also, and my bike idles for around 20 seconds then dies.

What is your jetting?

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Pilot may be a tad rich, hard to tell though. Pop a 48 in there to see.

Can you turn the idle screw in enough to make it idle? It may have worked itself looser than you think.

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i have the same problem, never can figure it out, thing wont idle for 15 seconds until its been wrung out all day. also you said you mix 50:1? how does that workout for you? seems lean to me. i run 38:1 and it runs clean at that for me here in Oregon at about 400ft above sea level. maybe its different over there, i have always wanted to lean mine but i worry about taking it a step to far i don't actually know whats recommended is it that lean?

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is the pilot jet clogged? this would cause what you describe. the idle air screw should make a noticable difference when turned from 1/2 turn out to 2 turns out, if not the pilot may be plugged, or try the 48 the 50 is rich IMO

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i have the same problem, never can figure it out, thing wont idle for 15 seconds until its been wrung out all day. also you said you mix 50:1? how does that workout for you? seems lean to me. i run 38:1 and it runs clean at that for me here in Oregon at about 400ft above sea level. maybe its different over there, i have always wanted to lean mine but i worry about taking it a step to far i don't actually know whats recommended is it that lean?

No one has ever hurt anything by running to much premix, AKA a lean fuel mixture.

As long as the bike is jetted for the proper ratio.

I run 32:1 and Castrol 927. I believe this may have some effect on my idle. This oil has a high flash point, and until the bike is completely warmed up to operating temps, some of the oil will not be burnt off. This could cause the plug to get wet or an excess amount of oil pooled around on everything, causing a less efficient fuel charge.

When setting my pilot circuit, I take the bike on a hard ride first. For some reason, my air screw and idle screw respond much better after the bike has had it's neck rung.

Premix oil not oil lubes everything, it also aids in ring seal. I read somewhere the peak power was made around 18:1.

I wouldn't suggest this mixture, but it is something to think about when you decide to decrease your oil to gas ratio, richening your mixture.

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thanks GMO397, very helpful, i wouldn't lean anymore without a professionals opinion anyways, not that you guys aren't professionals i just never know lol i run redline at 38:1 in straight clear premium and it seems to like it i just thought i might gain a little more snap leaning, but from what you suggest i suppose i stand to lose more than i would gain, thanks man! i will try fiddling with my carb screws/jets a little to try and halt the idle problem its especially troublesome when i jam my back break and drift the bike around tight trails, she dies every now and then and its just a little degrading ya know.

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I do have a 48 and I will try that tomorrow at the track. I checked the plug tonight and it was a brown color but it was more of a dark brown than the light brown/tan color. Goes against what everyone is saying about me being to lean with the 50:1. I'll try 42:1-36:1 and adjust the jetting from there, hopefully that will get me to a different starting point to work with.

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I do have a 48 and I will try that tomorrow at the track. I checked the plug tonight and it was a brown color but it was more of a dark brown than the light brown/tan color. Goes against what everyone is saying about me being to lean with the 50:1. I'll try 42:1-36:1 and adjust the jetting from there, hopefully that will get me to a different starting point to work with.

Just make sure you put in larger jets if you switch from 50:1 to 38:1 because the fuel mixture is becoming leaner.

It may or may not actually need rejetted.

But the 48 pilot would still be my vote.

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I put a 48 in last night at the track and that fixed everything. I now have it dialed in just right. Thanks for everyones suggestions.:thumbsup:

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