2003 Yamaha YZ 250 F Logo
A
Anonymous Posted on Apr 04, 2014

Can't start my yz250fp dirt bike

Cant kick start my bike cleaned carby, checked valve clearances, good fuel, new spark plug and getting spark

1 Answer

Gary

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  • Posted on Apr 04, 2014
 Gary
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Joined: Sep 14, 2010
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Have a trained tech service and properly jet the carb and set idle and idle mixture.
If you have spark, compression, and the valves are adjusted properly the only thing left is the carb. The FCR carb is as complex as the entire engine!

5 Related Answers

Anonymous

  • 1 Answer
  • Posted on Apr 05, 2009

SOURCE: hard to start yz250 dirt bike 2001 4stroke

i used to own a yz426f and it had the exact problem... a fresh plug will fix your problem. change the plug and the bike will run great. also don't start the bike and shut it off , my bike would be fine if i started it and rode for a while getting to the proper heat range help save the plug. if my bike didn't start in one or two kicks it was usually the plug.



hope this helps

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tombones

  • 3567 Answers
  • Posted on Apr 11, 2009

SOURCE: bike only fires once

Okay, let's have a look at it. Say Ahaaa.
The probable cause of the problem is not the spark. Get a fresh set of Stock NGK spark plugs, ground the plus to the engine, and check each cylinder for spark as the starter button is pressed for 3 seconds or so. I will wager that the spark is present.

The likely problem is the fresh gas was put into a very rusty gas tank. Bits of rust now inhabit your carb and are having fun plugging up the carb. Look at the gas valve. With a little luck there is a small bowl behind the valve. Remove it and tell me what you see in the bowl.

tombones

  • 3567 Answers
  • Posted on Jun 11, 2009

SOURCE: VERY hard starting takes way to many kicks usually play out befo

There is a proper way to start the engine. Four controls are on your bike to assist in starting.

  • The choke, used when the engine is cold. Pull the red knob for choke.
  • The " Hot Start " Lever, used when the engine is hot. Pull the lever to lean the fuel mix when the engine has been running.
  • The de-compression lever, always used.
  • The throttle, used to prime the cylinder.
Don't kick, instead, push the kick lever downward. You will feel the back pressure as the piston is going upward on the compression stroke to the point the pressure is great enough that the kick lever "locks up". You are very close to TDC. NOW, pull in the de-compression lever. Push the kick lever a little bit more to get the piston past TDC. Release the de-compression lever. Give the throttle a 1/4 turn then let it snap closed. A diaphragm in the carb gives a shot of gas when this is done. DO NOT do this multiple times because you will flood the engine. Leave the throttle closed when kicking. Give a strong kick through the full sweep of the kickstart lever. Quickly get your foot off the kick lever at the end of the kick to avoid any chance of "kickback" from a backfire. It can be very painful, and can even break a leg. I am serious about that. Repeat the process (but without the throttle priming), until the bike starts. A good battery, a clean spark plug, a clean carb and clean air filter will also aid in starting.

Top rating for this answer? Thanks!

Anonymous

  • 3 Answers
  • Posted on Nov 16, 2009

SOURCE: i have 1974 yamaha dt 250 enduro the bike sat

clean contacts on points with sandpaper (800 grit). located behind flywheel, will gurantee a fix. you can remove the side cover and get to contacts through holes in flywheel without removing it.

kel1guy2002

Kelly

  • 3740 Answers
  • Posted on Jun 10, 2010

SOURCE: fzr 600 got killer spark pulls fuel valves in

This is not the news you probably want to hear but backfiring thru the carbs when you have good spark can be one of 2 things... either the valves are sticking / not closing properly due to carbon or the cam timing has shifted from the original position.

It would be best to do a compression test. You should have a minimum of 100 PSIG for an engine with major problems and up to 150 for a healthy engine. If you can not get 100 PSIG then it will be time for some serious engine service.

There is a possibility of the kill switch wire in the handle bar grip grounding under the grip to the handlebar but, since you said you have killer spark I doubt this is your problem.

Thanks for using FixYa.

Kelly

Testimonial: "hey thanks for your help when i get stuck this is the first place i look for answers thanks again"

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