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yz250 2006 won't start

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Hi all i'm a long time lurker. This is a great forum full of usefull info.

My problem is I have a yz250 2t with a new barrel and piston that has about 160psi of compression and gets good spark. but it does not seam to suck fuel in should I look at the seals or would I need new reeds there is a slight 5 thou gap on one corner of the reeds.

Forward thanks for the help this is driving me mad.

:thumbsup:

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Take the airfilter off and try giving it a little shot of ether through the airbox with the fuel turned off. If it starts and runs for a couple of seconds, then you have checked timing, compression, spark, and the reeds. That leaves you with a carb issue of some sort.

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Dont use ether in a gas engine it will possibly score the piston. burns too hot. Just dump a bit of mixed gas in the spark plug hole. Id get new reeds if there old. If he put a new top end on more them likely he didnt touch the lower end the timing should be fine if it ran good before he did the top end.

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ok that might be possible because someone has messed with this before me and i have never seen the bike running. I had tried the fuel in the plug trick and also some areostart through the carb. But i was not aware you could get the timng wrong.:thumbsup: Will try tomorrow. Thanks

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Yeah don't go crazy with the ether, there's no oil in it. I agree with S14, all the major stuff should be fine. It's kinda hard to put the top end together wrong...

If there is :naughty:ANY:naughty: gap on the reeds, they are going to leak at low speed. I have had friends unable to kick their bikes, yet fire them easily when bump started on a hill. Upon further inspection the reeds were the issue. :thumbsup:

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Its not that ether dosnt have oil it burns too hot for a cold 2 stroke and will score pistons. My buddy use to wreck his snowmobile every year using the stuff. I finaly found the can and asked him when I did pistons for him once and he admitted to me he was using it. Ether can lightly score your piston and over time it will start harder because it will loose compression. He was always reliant on using either to start the snowmobile.

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Dont use ether in a gas engine it will possibly score the piston. burns too hot. Just dump a bit of mixed gas in the spark plug hole. Id get new reeds if there old. If he put a new top end on more them likely he didnt touch the lower end the timing should be fine if it ran good before he did the top end.

If used properly, ether will not cause any harm to your engine. A quick one second shot in the airbox is all it takes to verify spark, timing, and compression. The engine will only run for a second or two and then will die. Again, this is with the fuel turned off. The engine won't run long enough to develop much heat in the combustion chamber. I have done this for over 20 years, and have never had a problem.

Now, if you are going overboard and giving a 3-4-5 or longer second shot, then all bets are off and you are just asking to cause damage as you risk starving your topend of oil.

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160 lbs compression is REALLY low if it's a new top end (and cylinder). Should be in the 220-230 range. Check for air leaks, and that the piston is installed facing the correct direction, and the rings are installed right.

If it's not getting fuel (i.e. plug is dry), it's time to pull the carb apart and clean it.

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All right the timing option sounded most likley to me but as i said i didn't think that you could mess it up. but when i had a look in the manual it had some room for adjustment so i thought id take a look there first and to my suprise i found the nut on the stator not done up tightly and the key snapped. Im thinkng the previous owner didnt do it up properly. will get a key tomorrow and see if we can get it to fire then.:thumbsup:

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hmm. Got the key sorted and done the timing, but still no start going to pull the carb apart an make sure its all good. I need to do the clutch so I might do the seals while I'm in there. Will keep you all up dated. Thanks for the help

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Finally got back to the bike. Carby is clean and working correct. But i am still not getting any fuel into the engine. The reed has a small gap on one corner other then that it is sealed. I have done a pressure test and found 1 seal with a slight leak. To me these things seam minor but that might not be the case. Can anyone help with their experiances in these areas.

Thanks Again

Justin

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If you are not getting any fuel to the engine could be floatneedle or peckock.

Take the fuelline off and open your peckock to see that and if you got the carb bowl off you could blow by mouth through the fuel line to see if there is some resistance.

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+1.

If the plug is remaining dry, then you have a fuel issue. Most likely a carb issue where the floats are either not set correctly, or are stuck.

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Take the fuel line off your carb, turn on the gas and make sure the fuel flows out consistently for a few minutes.

Then hook the fuel line back up and remove the drain plug on the bottom of your carb. Turn the fuel on and verify it runs through your carb fine.

Then I'd but a new pilot jet, cheap and easy. But most just clean them.

If it still won't start, I'd check timing.

If it has an aftermarket crank, they are notorious for being timed differently than stock cranks. My hot rods crank was 5 degrees retarded from stock.

Good luck

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All good advice above.

Someone mentioned the piston possibly being installed backward... Take off the pipe and look through the exhaust port while you rotate the engine. If you can see a window cutout through the skirt, it's installed backward.

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rings,piston direction, carby, check waiting on the seals due in on tuesday. This might go now. Will keep you posted thanks for all the advice.

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rings,piston direction, carby, check waiting on the seals due in on tuesday. This might go now. Will keep you posted thanks for all the advice.

thatwasawesome, did you ever find a solution to your problem? I am having the same issue and can't seem determine why I can't get gas to the engine after pulling the carb and doing a thorough cleaning. I am going to replace the pilot jet but other than that, I have no idea.

I would like to hear if you figured it out. Thanks.

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Only found a slight leak in the crank seal other than that i can't find a thing going to put it back togeather this week and try and start it asap will keep you up to date. Let me know how you go if you make any progress.

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Its Alive...

Sorry for the late reply. The bike is up and running. Got it going yesterday, runs perfect. The last thing I did was confirm the ring were in right and replace the seals. The seal was definatly leaking so Im assuming that this was the problem as i didnt take to much notice of the rings just pulled them out then found the numbers and put them in facing up.

Thanks heaps to all that helped.

Now just want the torque that the crf450 I have been riding has. :bonk:

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