Question about 2003 kawasaki KX 250

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1980 Kawasaki KX 250, starts and runs hard.

Hi. I have a 1980 Kawasaki KX 250 that I decided to pull out of my brother's garage. It hadn't ran in 10-11 years or so I figured I'd mess around with it to see If I could get it to start. 2 Days ago I got it to start and run, rough but it ran. at the moment the only way I can get it to start is through the use of starter fluid and it still runs rough. It's running a ratio of 32:1, the carb was completely disassembled and cleaned, new gas, fuel line, and spark plug. I am not familiar with the world of dirt bikes or 2-strokes but I'm willing to give it a shot. Any help would be appreciated. Thank you

P.S. I don't know if this would make any difference but if I remember right the guy we bought it from raced it and i think had the engine bored and stroked

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  • speedy0069 Jul 31, 2009

    I've checked the spark, and I am getting a blue/white spark. I accidentally touched the end of the plug when turning it over, got a good zap. Good idea with the reeds. I will check those. The spark plug I do have in it is a (NGK) B7es, it calls for a B9es, it wont start on the B9 but it will run on the B7 not sure there what's going on. Fuel flows freely from the tank and there is no air filter element at this time. I guess if all else fail go thru the carb again.


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Have you pulled the fuel line off the carb to make sure fuel is flowing freely? Do you use the choke when you try to start it? When you say it is running rough, what exactly do you mean? Try to start it with the choke on and without starting fluid. After several kicks, pull the plug and see if it is wet. If not, pull off the bowl from the carb and see if it has the proper level of fuel. If not, maybe a fuel passage or jet is clogged, or the needle valve setting is messed up. Two strokes are simple, it's just a matter of fuel, spark and timing.

Posted on Jul 30, 2009

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Bored maybe, but i doubt stroked. They usually bored them because they blew up the motor, as it doesn't make that big of a difference in power.
Did you check ALL of the passageways in the carburator to make sure they are clear? Also, see that you plug has a fat blue spark, light yellow is a little weak, and may be due to corrosion around the flywheel.
Also the reed pedals can stick and hinder performance, and last, make sure the air filter is cleaned and re-oiled with a good filter oil.

Posted on Jul 30, 2009

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1 Answer

Well I just bought a kawasaki kx 250f it is very hard to start runs fine after it is running but once it shuts off hard to start also it is tough to find neutral

i had a similar problem with mine starting and re starting hard. my problem was the vavle clerance on the exhaust side. the vavle was so tight it took me 20 minutes or more to start it. once it fires ran fine, a littel hotter than usal. i check the vavles for the proper clearance i adjusted them to manufacture settings put a new plug in and vroom started in less than 5 kicks. also check the acc pump diphram they tend to dissolve with age and use one they got bad or get thin the bike will not run right. once you have checked all of this also change the pluge, always helps to have a fresh plug.

hope that gets you started any more qustions let me know

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Mar 15, 2011 | 2004 kawasaki KX 250 F

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Hi there i have a kxf 250 2004 its hard to start and when it does it back fires alot could it be valves

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Aug 10, 2010 | 2004 kawasaki KX 250 F

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Jul 11, 2010 | 2005 kawasaki KX 250

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When i first take it out of the garage it wont start. have to roll start. when it gets warmed up starts first kick . runs fine but when you let it sit and idle and punch gas quick it sputters then revs

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Sep 16, 2009 | 2004 kawasaki KX 250 F

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I have a kawasaki kx 250 2 stroke an it was running good now it wont start. it has spark it wants to fire up but it just backfires.

hi murray,

nice bike you have there.

have you checked on the carb ans see if the jet is right and the mixture is normal, this is usually the case if the carb is not tuned right.

better of reset the card, open it clean it, then set to default even if you are using your mixture of gas and 2t. just set to factory default. once it starts give it a few run, 1-2 hours, then set it to how you want your mixture to be.

hope this helps,



May 17, 2009 | 2003 kawasaki KX 250

1 Answer

I have a1987 kawasaki kx 250. it is very hard to kick

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Feb 25, 2009 | kawasaki KX 250 Motorcycles

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Kx250f hard starting

odds are your your intake valve lash is tighter then spec or gone.
check that first

Nov 18, 2008 | 2004 kawasaki KX 250 F

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