Question about 2003 Yamaha YZ 125
We replaced the stator and put a new spark plug and Carb. The bike just backfires after several kicks? The spark plug is wet each time we check. Is there some kind of timing issue? The piston is definitely getting spark?
Posted by Anonymous on
Hi, Anonymous and the usual suspects are:
1. Severely discharged or a damaged battery, should have 12.5 volts or better and be able to pass a load test if necessary.
2. 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.
3. Faulty main circuit breaker and or connections.
4. Faulty ignition coil and or connections.
5. Faulty spark plug, oil or gas fouled, wrong heat range or service type, wrong gap, loose in the cylinder head, broken electrode or insulator.
6. Faulty spark plug cables, leaking or broken, internal damage.
7. Faulty ignition module, switch, CKP, MAP, CMP, sensor and or any connector in the ignition circuit could have corroded, loose, or broken pins/sockets
8. Burnt exhaust valve or air leak in the exhaust system.
For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
Bike won start just backfires occasionally
01 FZ wont start after back fire FZ1OA Message Board
Yamaha YZ125N1 Service Manual
OEM parts for Yamaha
Posted on Jul 13, 2016
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Posted on Jan 02, 2017
SOURCE: YZ 450 STARTING PROBLEM
Hi and welcome to FixYa,
Offhand, the backfire is significant. It indicates that fuel is getting inside the combustion chamber and it further confirms that there is spark. Being the case, it would appear that this is now a timing issue. A couple of ideas to explore:
Posted on Dec 15, 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
SOURCE: yamaha yz80 wont kickstart
There is a "C" clip with a stem at a right angle as a part of the clip. This is a part of the kick starter mechanics. Replace the clip. It is about one inch in diameter.
Posted on Mar 12, 2009
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.
Posted on Nov 16, 2009
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