I'm stumped...bike won't start, plug is dry

Joined
Apr 30, 2007
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#1
This topic is about a 1998 YZ 125

A few months ago I was riding my bike for hours on a really hot day, when suddenly it just shut off. After sitting for a few minutes to let it cool down, it fired up again, only to shut off again a half hour later, this time for good. I tried kicking it and kicking it over the next few weeks, and got nothing.

I thought maybe it was the plug, so I replaced it and still no change. Then I noticed the plug is actually dry even after I kick the bike a few times. I am getting compression, and getting a spark, however no gas is getting to my spark plug. I've cleaned out the carbeurator time and time again, being absolutely sure that there are no blockages inside there.

I've also taken out the reed valves. I'm not very experienced at reed valves, so all I'm going by is my observation. Still look to be in good shape, and all four flaps are pressed tightly against the support in the middle. I'm presuming they should be closed in their resting position. When I place a flashlight inside the back of the reed valve, light escapes through very small slits all around the flaps, which I'm also assuming is normal, considering the materials this part is made of. My manual says the reed valve should have 2 mm of give, or something along those lines, and I'm not sure how to interpret that.

I have provided all the information that I have. Any opinions on what my problem could be? Since no gas is getting to my spark plug, and I have compression, I'm assuming it's got to be a carb or reed valve issue. I thought about buying a rebuild kit for my carb, and buying a new reed valve, but I'm a college kid and money's tight, so I want to have a good idea that it will help the problem before I go spend money on it.

Thanks for any help.
 
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Apr 8, 2007
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#2
fuel filter/ fuel lines blocked? fuel petcock clogged, have you tested it with a compression tester?
 
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Apr 18, 2006
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#4
rogcha_22 said:
I've cleaned out the carbeurator time and time again, being absolutely sure that there are no blockages inside there.

When you take the carburetor off, has it always had a full bowl of gas?

If you end up spilling ~1/2 cup of gas when you take the carburetor off then it is a good indication that gas is getting into the bowl. On the other hand, if the bowl is dry then it is a clear indication that you have a gas supply problem: either the float is stuck, the needle valve is clogged or the tank is clogged.

If you are getting gas to the carb then I recommend the earlier recommendation: run a compression test. It does sound like a seize situation

Rod