2009 shenke yy250t-2 no spark

It does seem like an ignition problem.
I don't have specs for your motor, but generally Resistance type HT (spark plug ) leads should show up to 10K ohms or less so infinity means a gap somewhere .
Primary side of the coil can be as low as 0.5 ohms and up to 100 ohms.
Make or buy a spark gap tester. Be careful not to hold the wires or tester. You would know that this is high voltage, but others reading this may not on first try.
Cranking the engine with spark plugs removed keep the tester away from the spark plug holes and any fuel. The spark should jump 5/16th" or more.
If it's only one spark that is weak then it's most likely the plug coil, but to be sure swap it with another to check to see if the weak spark goes with it, otherwise it's most likely a CDI unit. If all sparks are weak then it could be the CDI charge coil or the CDI unit. You would need to find the output specs for the charge coil to confirm which is the problem. Often they put out 150 to 200 volts AC at cranking speed
I hope that helps

And ignition coil has two sets of wires one to a primary winding and the other is for the secondary winding the secondary winding has the large rubber cord that goes to the spark plug and the other and goes to ground the other winding the primary winding has one and it goes to ground and the other end that goes to your magneto source if you take a ohmmeter you should be able reader crossed the primary input winding wire to ground It Should Not read zero nor infinity The same is true of the secondary winding across the spark plug wire and ground if this Brpward where is a carbon filament where you may get a very high reading but not infinity

Remove the plugs and visually check the condition of the plugs and then reinstall them and leaving both plugs installed remove the spark plug cable from one of the spark plugs and THEN attach the HT cable to a SPARK TESTER and clip the tester to the cylinder head bolt and crank the engine over looking for spark and repeat the procedure on the other cylinder also. Be aware that the Engine will not spark with both spark plugs removed, so when checking for spark, use a SPARK TESTER with both plugs installed.



If you have no spark test the coil first. There should be power to the coil primary all the time the run switch and ignition switches are ON. If not check all switches, relays and fuses.

If the CKP is defective you will also get no spark so check it last.

Test the primary coil resistance on your coil. Disconnect all the wires going to the small terminals (primary) on your coil. Using a good ohmmeter on Rx1 setting, test the resistance between the two small terminals. You should read somewhere between 2 and 3 ohms. If you read more, the coil is bad. Before you do this test short out both leads of the ohmmeter and if the reading is not zero you will need to write down or otherwise remember the number and subtract it from the reading you get from the primary circuit test or you will have an incorrect resistance reading for the primary wires because you will also be reading the ohmmeter internal resistance and/or the wire and lead resistance added to the primary wiring resistance.

You can also test the coil by leaving the "hot" wire on the coil and replacing the other side (ground side) with a short piece of wire. Turn the ignition on and temporarily ground the short piece of wire you put on the "out" (ground) side. When you take the wire away from the ground, (which will collapse the primary current into the secondary) you should see a spark at the plugs if it is a wasted spark system or at one of the plugs if it is not a wasted spark system. If you have current to both sides of the primary of a two part coil both plugs should get a spark whether wasted spark system or not as you are energizing both sides of the primary and collapsing both into both secondaries at the same time when you remove the ground wire from the cylinder head ground.

MORE:

Ignition Coil Primary Circuit Test
Remove the coil. THEN set your ohmmeter scale to RX1 and place ohmmeter leads on the primary coil windings A (front of coil) to B (middle of coil), B to C (front of coil) and check for primary coil winding resistance which normal resistance range is 0.5-0.7 ohms. If primary resistance is not within this range check out test results below.

Ignition Coil Secondary Circuit Test
With the ignition coil removed from the motorcycle and the ohmmeter set to the RX1K scale place the ohmmeter leads on the secondary coil windings B (middle terminal) to
R (rear secondary terminal/socket), B to F (front secondary terminal/socket) and check for secondary coil winding resistance which normal resistance range will be 5.5-7.5K ohms. If secondary resistance is not within this range check out test results below.

Test Results
A low resistance value indicates a short in the coil winding which requires coil replacement.

A high resistance value might indicate that there is some corrosion/oxidation of the coil terminals requiring the coil terminals to be cleaned and the resistance test then repeated and if after the test is repeated the resistance is still high after the terminals were cleaned the coil must be replaced.
If there is an infinite ohms or no continuity) resistance value the coil is open and must be replaced.

Sounds like all there is left is the plug wire from the coil - but it's probably a single unit - coil and wire w/ plug boot.
All that comes to mind is grounding. With a VOM make sure you have a ground. Also look further up the chain - follow the wiring the CDI unit plugs into for breaks. Headlight gets brighter when kicked over ? Follow the wiring to it's termination points, loose plugs etc.

Single cylinder engines vibrate an awful lot, with that in mind look things over. There is a chance the no spark condition is a product of an unrelated failure - ignition system could be fine. Check the stator coil for an open circuit where it should be closed.

Besides checking wire and plug condition, cleaning and tightening grounds. The stator is the first place I'd check.
Be careful and gentle, the coil wires are very fine and as such break easy. A shorted winding will show continuity but not generate power, a web search should give resistance ranges of the coil assy.
Too low fail/Too high fail ranges.

My brain is picked out....Hope it helps you.

CHECK THIS AS A STARTING POINT:

First check for diagnostic trouble codes (DTCs). THEN check the condition of the battery and do a voltage test and recharge the battery if it is below 12.60V. THEN check the condition and tightness of the battery connections and perform either a conductance test or a load test and replace the battery if and as necessary. THEN remove the spark plug cable from one of the spark plugs and remove the plug and visually check the condition of the plug. THEN attach the HT cable to a SPARK TESTER and clip the tester to the cylinder head bolt and crank the engine over looking for spark and repeat the procedure on the other cylinder also. Be aware that the Engine will not spark with both spark plugs removed, so when checking for spark, use a SPARK TESTER with both plugs installed.
Typically, when IAC is not functioning, the engine will not start unless throttle is opened and the engine will stall when throttle is closed.
Check TP sensor value with digital volt/ohmmeter (DVOM). If TP sensor is equal to or greater than 3.8 volts, system is in "clear flood" mode and engine will not start. While spark is present, fuel is shut off. Problem can be mechanical, such as throttle cables stuck.

No Spark with No Check Engine Lamp at Key ON

Constant power is supplied to the ECM through terminal 31. The ECM turns on when power is applied to terminal 13 of connector [78]. The ECM goes through an initialization sequence every time power is removed and re-applied to terminal. The only visible part of this sequence is the check engine lamp. Upon starting, the check engine lamp will illuminate for 4 seconds and then (if parameters are normal) go out. If battery power is absent at ECM terminal 31: DTCs cannot be cleared. The tool will show them as cleared but they will be present the next time the ignition key is cycled; the ECM cannot be re-flashed; the vehicle will start but the IAC pintle will not reset at key OFF and eventually the pintle will be out of position causing performance problems.
NOTE: The key ON sequence also activates the idle air control motor. If power from terminal 31 is disrupted by a (blown fuse, etc.) always turn the key OFF wait 10 seconds then turn the key ON to reset the motor to the default position.

Test the primary coil resistance on your coil. Disconnect all the wires going to the small terminals (primary) on your coil. Using a good ohmmeter on Rx1 setting, test the resistance between the two small terminals. You should read somewhere between 2 and 3 ohms. If you read more, the coil is bad. Before you do this test short out both leads of the ohmmeter and if the reading is not zero you will need to write down or otherwise remember the number and subtract it from the reading you get from the primary circuit test or you will have an incorrect resistance reading for the primary wires because you will also be reading the ohmmeter internal resistance and/or the wire and lead resistance added to the primary wiring resistance.

You can also test the coil by leaving the "hot" wire on the coil and replacing the other side (ground side) with a short piece of wire. Turn the ignition on and temporarily ground the short piece of wire you put on the "out" (ground) side. When you take the wire away from the ground, (which will collapse the primary current into the secondary) you should see a spark at the plugs if it is a wasted spark system or at one of the plugs if it is not a wasted spark system. If you have current to both sides of the primary of a two part coil both plugs should get a spark whether wasted spark system or not as you are energizing both sides of the primary and collapsing both into both secondaries at the same time when you remove the ground wire from the cylinder head ground.


ALSO check, test your plug wires and wire ends.

Ignition Coil Secondary Circuit Test
With the ignition coil removed from the motorcycle and the ohmmeter set to the RX1K scale place the ohmmeter leads on the secondary coil windings B (middle terminal) to
R (rear secondary terminal/socket), B to F (front secondary terminal/socket) and check for secondary coil winding resistance which normal resistance range will be 5.5-7.5K ohms. If secondary resistance is not within this range check out test results below.

a mower with a bad coil has no spark and will not run. you know something is wrong if the mower will not run. if you take out the spark plug , from the engine and connect the spark plug wire to the spark plug and lay the spark plug on the engine block so that the spark plug makes a good ground connection from the spark plug body to the engine metal and then have a friend pull the recoil starter rope, you will see a spark jump from the inside terminal of the spark plug to the arm of the spark plug that is part of the spark plug body.
if you see no spark, then there may be something wrong with the coil or with the primary ignition circuit.

You must have a friend pull the recoil starter because it is nearly always impossible to see the spark when you are trying to pull the recoil starter yourself. you cannot see the spark because you are moving to much to focus your eyes. the spark is hard enough to see from 12 inches away.
You can test the spark coil by removing it from the mower but only if it is an automotive type spark coil. I have a feeling that it is not an automotive type spark coil. you can test the primary winding of the spark coil for continuity with a $10.00
multi meter from walmart,home depot or lowes or harbor freight
You must fully read and fully understand the instructions.of the multi meter in order to use the multi meter without burning out the multi meter. you can test the primary windings of the coil with the coil electrically disconnected from the lawn mower. you must make writen notes so that you can reconnect the coil exactly as you removed it.
the primary windings of the coil should read between 10 to 1000 ohms. if there is no ohms reading the coil is open,no connection and you need to buy a new coil. if the primary winding has a resistance (ohms reading) the coil has conitinuity but still must be tested for shorts to ground. on the highest resistance scale that your meter has , put one test probe on one terminal of the primary winding and the other test probe on the ground of the coil or the case of the coil. a good coil has no ohms reading fromthe coil primary winding to ground.

you should buy a lawnmower repair manual for your make and model of lawnmower because there is a lot to this and i cant type that much. too much for me to tell & too much i dont remember. Its been 15 years since i worked on an ignition system of a lawnmower. try asking your question on youtube.com and on google.com or ask.com, bing.com and study up on it.

I would start by checking your coils, the primary resistance should read 0.5 ohms the coil secondary resistance ( spark plug removed) 6400 ohms then if thats good check thepulse coil air gap 0.016 to 0.030 inch and the pulse coil resistance white/red to white 522 ohms and white/red to ground inifinity ohms and your spark plug cap resistance 5000 ohms. In the mix of all this I would also check that all the connections are tight. Good luck.

Below is a generic proceedure for checking your ignition coil.

Ignition Coil Resistance

• With the key off and the battery lead to the ignition coil disconnected, use an ohmmeter to measure the primary and secondary winding resistance of the ignition coil. when checking the resistance across the windings, pay particular attention to the meter reading. if the reading is out of specifications, even if it is only slightly out, the coil or coil assembly should be replaced.
• To check the primary windings, calibrate an ohmmeter on the X1 scale and connect the meter leads to the primary coil terminals to test the winding.

Ohmmeter connected to primary coil terminals.

• An infinite ohmmeter reading indicates an open winding. The winding is shorted if the meter reading is below the specified resistance. Most primary windings have a resistance of 0.5 to 2 ohms, but the exact manufacturer's specifications must be compared to the meter readings.
• To check the secondary winding, calibrate the meter on the X1,000 scale and connect it from the coil's secondary terminal to one of the primary terminals.

Without a fully operational Crank Position Sensor a bike will not start. The CKP sends a signal to the bikes ECU (also known as CDI, this is the bikes "computer") telling it that the pistons are in the correct place and the spark plug needs to fire. The ECU processes this information and sends a signal to the Ignition Coils, this then causes the spark plugs to fire. Without the CKP sensor the ECU doesnt know when to tell the coils to fire the plugs.

If you are not getting any spark either:
1. HT leads or spark plugs are faulty.
2. Coils are faulty, use a multimeter to check the resistance across the primary and secondary windings. Should be (from memory) around 3000ohms for primary and 30,000ohms for secondary.
3. CKP sensor is faulty. Use a multimeter to check the resistance of the coil windings. From memory should be about 300 - 500 ohms.
4. A wire is shorting out somewhere, or there is a bad ground conection.
5. If none of these is faulty then your ECU is probably the culprit. Sadly the only way to test an ECU is by swapping it out with a known good one.

I've this data from my 1986 engine!

Under the left hand side cover there are 2 2-wire connections. One with a green and a black wire, one with a blue and a yellow wire.
Use an ohmmeter at R x 100 between both wires of a connector to check the pick-up coils: resistance must be between 130 and 180 Ohms.

The values of the ignition coil resistances are:
primary coil : 3-5ohms ( set ohmmeter at R x 1 )
Secundary coil : 25.000 - 45.000 ohms ( set ohmmeter at R x 1.000 )
For a correct measurement ALL leads must be disconnected ( also the spark plug leads )

The CDI cannot be tested with a simple measurement. Suzuki dealers have a special tool to test CDI boxes.
But checking the pick-up coils and ignition coils good will indicate an defective CDI.

The wires on the CDI:
Blue: PU coil 1 ( cyl 1-4 )
Yellow: PU coil 1
Green: PU coil 2 ( cyl 2-3 )
Blue : PU coil 2
Orange/white : +12v ign coil 1-4
White : switched coil negative side ign coil 1-4
Orange/white : +12v ign coil 2-3
Blue/yellow: switched coil negative side ign coil 1-4 ( and signal to tachometer )
Blue/white : ground

Thus, you must have +12V on both Orange/white leads.