Ignition I have a yamaha FZ6 with points ignition and it will only spark part of the time when you kick it over. I've had it run but it would only run for about 5 seconds.

You need a wiring diagram or service manual to check the way the circuit runs and whether it earths via the points or earths via the coil. The way the spark works is that the coil is energized all the time the ignition is on and the spark is created when the the points *break* the contacts.

You will only have power at the points with the ignition on and only on one side with the points open.

Various resources in the link, but none that I am willing to register for.

https://www.google.com/search?q=1971+yamaha+dt250+ignition+wiring+diagram

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Have you check the Engine Control Unit? Fuel injection systems are generally electronic and are controlled by a small computer. If it fails it would stop the engine running. The fact that the bike starts with externally supplied fuel would point towards an ECU problem.

Hi, is this still on points ignition? The spark should occure between .5 and 1 mm before top dead centre, on some of the older machines the ignition timeing is not addjustable as the backing plate is fixed, however the ignition timeing can be determined by the correct points gap, the points should open at the correct time as the piston reaches the top of the stroke, if you dont have a top dead centre gauge, you could improvise by making some markings on a thin rod which you will insert into the spark plug hole, rotate the engine in the correct direction by hand until the piston is at top dead centre, that is the piston has reached its upermost stroke before it starts to decend, at tdc turn the engine back the required amount untill your markings point out the required amount, it is at this point the points should just sepparate creating a spark, a test light with a small 9volt battery in line will indicate the separation of the points, i would however like to stress the third most important item to make a two stroke run is compression, spark and fuel alone is insufficiant without it, on machines that have been standing for long periods of time the piston rings can become stuck in the piston, not allowing the rings to seal the bore, remove the exhaust and look up the Port the piston should look as new with no scoring to it, any damage will prevent the engine from running, as will worn crankshaft oil seals which can become soft from old fuel contamination

you need good compression ( at least 90 psi , kicking it with the throttle open) , good crankshaft seals for sucking the fuel/air into the botton end, proper point gap and timing set for spark ( spark should be big and fat,if not the source coil is weak,, this is a flywheel magnito ignition and it needs no battery to fire the plug) if you clean the carb, make sure you also clean the choke pickup tube or it wont choke. also make sure you have the slide installed in the right direction ( not backwards and the idle is not set too high at first...compression/****-good spark at the right time-proper fuel/air ratio and it will run

Hello,

Remove both sparkplugs from engine. Plug them back in the sparkplug cables and let them rest on the engine.
Make sure your battery is well charged.
Check for sparks while kick-starting...
Interchange the sparkplugs in the cables:
-Same plug give sparks: replace the spark plugs.
-Same side of engine sparks: interchange the low-voltage connector at the ignition coils.
Give it a try:
Same engine side sparks: Replace the defective ignition coil.
Other side of the engine sparks: Check the circuit harness for loose connectors, and/or Clean-replace the breaker points ( left side of the engine carter ).

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