Question about 2003 Yamaha YZ 450 F

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'03 450 always seems cold-

Rediculous to start this bike cold, you gotta tow it for 100 yards. it can be adjusted to fire in one kick when it's warm, though it kicks way way to easy. go ahead tell me......

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Do a compression check. It should be 120lbs or above. Check the compression release. Is it closing fully? Burned valves may be at play here also. Bad piston rings or seize scars on the cylinder wall? If you need a service manual you can download a free PDF from the site below.

http://www.carlsalter.com/motorcycle-manuals.asp

Please rate this answer. Thanks ellismd79!

Posted on Apr 20, 2009

  • tombones Apr 20, 2009

    I forgot > install a fresh NGK stock spark plug.

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Honda shadow vt1100c 1986 idile to low after running awhile


There's an idle adjustment screw. The bike runs faster when cold because the fuel\air adjustment is richer on a cold engine. When the bike warms up, the fuel becomes more lean in mixture because the heat causes the fuel to expand, i.e., less molecules of fuel to the firing sequence of the piston. When the bike is warmed up, after say ten minutes, the heat causes a leaner mixture, so adjust the idle on a hot engine (about 1000 rpm more or less). The bike will idle faster when cold, then drop rpm's as the engine warms up. Good luck

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KICK HARDER TRY PULL STARTING IT..IN SECOND GEAR..DOES IT HAVE ENOUGH COMPRESSION TO START?IT SHOULD START PULLING IT...START OFF WITH NO THROTTLE THAN IF NOT STARTING CRACK THE THROTTLE SO LIGHTLY AND SHE SHOULD FIRE OFF WHILE IN GEAR BEING PULLED OF COURSE BE CARE FUL NOT TO RUN INTO. WHO EVERS PULLING YOU..USE A LONG TOW ROPE..IF YOUR NOT A SEASONDED RIDER AND KNOW YOUR BIKE VERY WELL I WOULD NOT ATTEMPT THE PULL START...IF NOT CHECK YOUR COMPRESSION AND TIMING..MAJOR VACUUM LEAK MAYBE AT BASE GASKET..IS ENGINE SUCKING TO MUCH AIR? GOOD LUCK..

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1 Answer

JUST BOUGHT A '73 XLCH THAT SAT FOR 2 YEARS BECAUSE THE OLD MAN THAT OWNED IT COULDN'T KICK START IT ANYMORE. IT STARTS RIGHT UP BY PUSH STARTING IT, BUT KICKING IT IS ANOTHER STORY. IT'S GETTING FIRE...


You probably need to adjust your valves. Ironhead Sportsters are equipped with solid lifters and must be adjusted with zero backlash. If one of the pushrods is adjusted just a bit tight and holds a valve open even slightly, the bike is almost impossible to start with the kickstarter.

To adjust the valves, the bike must be stone cold. Take the spark plugs out, raise the rear wheel of the ground, and put the transmission in fourth gear. Turn the engine over by bumping the rear wheel in the normal direction of rotation. Bring the piston of one of the cylinders up to top dead center on the Compression stroke. Pop the pushrod tube covers and check the pushrods. You should be able to spin both pushrods with your fingers. If not, adjust the pushrod so taht it's tight. Then back it off to where you can just spin it with your fingers. Keep in mind that on a Sportster, it's better to have the pushrods slightly loose than tight. Once you get that cylinder's pushrods adjusted, do the same thing with the other cylinder.

Now, once you get this done, starting your bike is simply a matter of figuring what works with it. I've always said that kickstarting a Harley, especially a Sportster, is a ritual. Some bikes like for you to milk the throttle twice, kick the engine through twice with the choke on and ignition off, then turn on the ignition and kick it. Other bikes seem to want only one milk of the throttle, one kick with the ignition off, and then kick it. Each bike seems to have it's own particular ritual that you must figure out to get reliable starting. I'd try milk the throttle once, put the choke on, kick it through with the ignition off once, then turn the ignition on and kick. If the bike spits back through the carb, you need to start all over again. If you get the engine flooded, hold the throttle wide open and kick until it fires.

One other thing about a Sportster. Did the old man you bought it from have a limp in his right leg? A Sportster is notorious for "slipping through" when you try to start it. The result is that all your weight comes down on your knee without any resistance. The result is your knee tries to bend backwards, the way it wasn't designed to do. This can tear ligaments and cartilage in the knee and it even has it's own name, "Sportster Knee". Be careful.

Ride Safe
Steve

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Its a 4 stroke trail bike. They never like to start when its cold. Just make sure the plug is good and make sure the choke is actually working. Other than that, kick it until you get mad, then kick it some more and it will eventually start.

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1 Answer

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1 Answer

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2 Answers

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1 Answer

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