Question about 2002 Yamaha YZ 426 F
Hi guys my 2002 yz426f wont start when its cold !! changed the spark plug replaced the carburetor with one that placed on a yz450 that does start in first kick the thing is when i do start it by pushing it and riding it for 10-15 minutes it does start in a kick any one had this problem and can help me solve it ??
Hi, Jacki_edri and the usual suspects are:
1. Spark plugs in bad condition or have an improper gap or are partially fouled.
2. Spark plug cables in bad condition.
3. Battery nearly discharged, should have 12.5 volts.
4. Discharged battery, check battery terminals for damage or corrosion, check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter if necessary.
5. Throttle controls not adjusted correctly.
6. Water or dirt in the fuel system.
7. Water or dirt in the carburetor.
8. Intake air leak.
9. Fuel tank vent hose and vapor valve plugged, or fuel line closed off, restricting fuel flow.
10. Enricher valve inoperative.
11. Engine lubricant to heavy (winter operation).
12. Ignition is not functioning properly (possible sensor failure).
13. Faulty ignition coil.
14. Valves sticking.
For more information about your issue and valuable "FREE" downloads that you will need please visit the websites below. Good luck and have a nice day.
YZ426F cold start problem question
how to start cold start yamaha yz426f
Yamaha YZ426F Owner Service Manual
OEM parts for Yamaha
Yamaha YZ450F Owner Manual Page 3
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Posted on Aug 02, 2016
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Posted on Jan 02, 2017
SOURCE: My YZ426F has fuel and
Thankz to the fixya team,
between my dad and i, we managed to solve the problem. Regards to the starting, well all we did was change the plug, the original plug had a faint spark, after fitting the new one, two tries and she started. With regards to the exhaust, well the hot start knob has a valve and this valve has a little spring that operates it. Well this little spring was really knackered and after replacing it with a substitute spring, ive not had any problems since. We reckoned it was getting to much air into the combustion chamber, therefore igniting petrol in the exhaust, (hence the glowing red hot pipe) since we changed that spring, this hasnt happened, we reckon thats the solution to this problem.
Posted on Nov 17, 2008
SOURCE: yamaha yz125 wont start...
hello there guys, listen a top tip is when the engine's cold tip the bike almost right on its side nearly touching the floof, wait for the petrol to poor out of the carb over flow pipe, this should take a matter of a few seconds, stand the bike back up again and kick and that baby should start right up, if it does then you have a problem with your float, if it still doesn,t then take it to a shop and get them to check it out, hope this helps. regards sam
Posted on Jan 24, 2009
Here are a few things to do >>
How old is the gas in the gas tank? Get fresh fuel.
Remove the water trap bowl at the bottom of the petcock, (gas valve). Any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Clean the bowl and filter screen if present, then re-mount them, ( not all bikes have a water trap bowl or screen ).
Install a new stock NGK spark plug and try to start the engine. If the bike doesn't start and run properly then shut off the gas and remove the carburetor from the engine.
Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Remove the two screws on the outside throat of the carb and spray into the screw holes as well.
< < READ CLOSELY > >
Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. Set the idle speed with the idle screw.
I am uncertain if the bike has ran for you or not. "Did pull the spark plug and kick started it." If the bike still will not run then the cam chain may be out of time. Why was the tensioner off the bike?
Please rate this solution. Thanks budx5!
Posted on Apr 04, 2009
There's only two , on the Ca. model , sitting on the bike second cylinder from left, the synching port goes to the petcock -on the carb joint nearest the block- It would be the only boot without a black cap n a spring clamp .And (it'll be a long hose) goes to the emissions can behind the air box on the right from the carb itself.(it has a plastic cover over it) Anything behind the carbs (between 1n2 then 3n4 ) is over flow tubes to the bottom of the frame.
Posted on Apr 29, 2009
SOURCE: 1989 tw200 yamaha won't start
G'day egdbcs . Ok.now lets see.You say good spark,so i'm presuming you are doing the old sight test.Try bending the arm on a know good sparkplug about 5-6mm,earth the plug and kick'er in the guts(crank it over)Be very carefull , high voltage danger.If there's still a good spark it's safe to say that there will also be a good spark under pressure in the combustion chamber,speaking of which you should also do a compression test,anything over 100psi should be ok. as i'm not to sure of the extent of the re-build,hopefully the valves were lapped and checked for straight and true and valve seals replaced,if you notice oil on the tip of the spark plug you could have a leaking valve seal or oil seal .Try putting a small amount of fuel directly into the combustion chamber ,tighten up the spark plug ,install the plug cap and.......Yeah ..You guessed it ..."kicker in the guts".If all the abouve are correct and true it should fire up.If it runs for 5-10 seconds then stops you've got some sort of fuel starvation problem , could be dirt in the carb,blocked idle jet ,or air passage or even the needle could have come off it's clip,believe me with an old bike like yours anything could be worn and loose inside that carby.The only other thing to consider is the timing.There may be a good spark but is it happening at the right time inside the engine???. I'll leave it all in your capable hands EGDBCS.Hope this helps to solving your worries. Chow for now......Tilleydog..
Posted on Jun 03, 2009
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