Need Help Bike Wont Start

Joined
May 28, 2007
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#1
Hey guys ,
Im new to riding and to this site. i just bought a 2003 yamaha yz 125 I had it at the shop last week to get a tune up ,new spark plug, change fluids etc, and put in a fmf exhaust. i went riding on sat and hit a jump and landed doing a endo. the bike dropped on its right side (brake side) but didnt drop that hard. I bent the brake lever but I didnt see any other damage. well I tried to start the bike and it wouldnt start. when I got home I took out the spark plug to clean it and sandpaper it down. still no good. I tried to push start it, it turns over when I drop the clutch but once my friend stops pushing it shuts off. my friend thinks the carberator is flooded. but I dropped the bike on saturday and its monday now, shouldnt it have dried up by now? i'd really like to ride again soon and I dont want to bring the bike back to the shop and pay more $$$, so any help would be much appreciated. thanks :ride: oh, one more thing, when im riding and i come to a stop in 1st gear and i have the clutch in my bike just shuts off. someone told me dat b/c these bikes arent ment to idle so it shuts off. but if i have the clutch in shouldnt it not make a difference if im in 1st, or neutral and not moving? the bike should stay on shouldnt it? do i have a bad clutch?
 
Joined
Apr 18, 2006
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#2
The idea of taking sandpaper to a sparkplug bothers me.....
Just be very careful that you don't leave any bit of sandpaper grit down in the sparkplug. You really, really do not want those dropping down into the cylinder.

To find out what is wrong, start with the basics. In order to run, an engine needs air and fuel (mixed in the proper proportions), compression, and a spark (at the proper time) to ignite it.

You have obviously kicked the starter a bunch. You should be able to feel the compression. If if kicks over easier than it used to then you should get a compression tester and make sure that you have adequate compression.

If you have been kicking the bike a few times and it won't fire, then pull the plug. If it comes out bone dry then you most likely are not getting any gas. You could be out of gas, the valve could be turned off, there could be a clog in the line, the float valve could have stuck closed or the jets could be clogged. I doubt that the jets would clog as a result of a crash, the fuel valve is on the left so it is unlikely that the fuel line got kinked or otherwise damaged, and I am making the assumption that you have gas in the tank. It is possible that the impact damaged the float, but I doubt it.

If the plug is wet then either it is flooded, the plug is fouled or you are not getting spark. Put the plug wire back on the plug, hold it against the cylinder head and kick the starter. You should be able to see a good, healthy spark across the tip of the plug. If you don't then either the plug is fouled or there is something wrong in the ignition. I recommend swapping in a new plug. If you still don't get spark, then check your kill switch, it is possible that in the crash the kill switch took a hit and has shorted out. Check all the wiring to see if something was jarred or torn loose.

If you are getting spark, compression and gas and it still won't run then it is likely that the engine has badly flooded. The air to gas mixture has to be correct, too much gas is as bad as not enough. It is possible (in fact, it happens a lot) that a bike laying on its side will allow gas to flow out of the carburetor and directly into the crankcase. You can end up with a sizeable puddle of raw gas down in the crankcase, and as long as it is there the bike will never run!

If you turn the gas off at the tank, hold the throttle wide open and kick it enough it will eventually dry out. You may wear your leg out before this happens, however. You can speed the process up a lot by turning the gas off, removing the plug, turn the entire bike upside down (rest it on the handlbars), then operate the kick starter (by hand, it is a bitch to kick in this position) the engine over a bunch. If you see liquid squirting out the spark plug hole then keep kicking it until you don't see any more liquid. Turn the bike right side up, put a dry plug in, turn your gas back on and then try again.

As for the bike stalling at idle; it is a common problem. If the bike will idle okay when in neutral but won't idle in gear with the clutch in it is probably because there is excessive amount of "clutch drag". Changing the gear case oil can help, and you might be sucessful at simply increasing the idle speed, but if the problem persists then the only real solution is to tear into the clutch and find out why it drags so much.

Rod
 
Joined
Apr 8, 2007
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#3
rmc_olderthandirt said:
Put the plug wire back on the plug, hold it against the cylinder head and kick the starter. You should be able to see a good, healthy spark across the tip of the plug.

i just thaught that i would add that the spark should look like a big blue spark, if its roange its weak. Some people think if they have a spark its good enough.