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1976 YB100 NO SPARK


sportique150
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Hi there i have just bought a 1976 Yamaha YB100 from a bike show it is pretty rough but 100 percent complete.The problem is that when i kck it over it wont spark the neutral light comes on so i am assuming that the stator is ok but could it be the ignition source coil in the stator that is at fault. i have tried a new spark plug a new coil adjusted the points disconnected the ignition switch still nothing i have bought a new condenser and points but have not had a chance to fit them yet and i dont want to do anymore to the bike till i get a spark any help would be much appreciated Ian

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Hi there i have just bought a 1976 Yamaha YB100 from a bike show it is pretty rough but 100 percent complete.The problem is that when i kck it over it wont spark the neutral light comes on so i am assuming that the stator is ok but could it be the ignition source coil in the stator that is at fault. i have tried a new spark plug a new coil adjusted the points disconnected the ignition switch still nothing i have bought a new condenser and points but have not had a chance to fit them yet and i dont want to do anymore to the bike till i get a spark any help would be much appreciated Ian

Hi Ian,

First off check that the ignition timming is correct .. this should be 1.8mm btdc as the points open, this should be done via a dial guage (to measure the piston back by 1.8mm) and a sensitive ohm meter to work out when the points open & close. but other things to look at ... the coil are the primary & secondary windings giving the correct read outs (I would not think this as the YB coil lives in a nice place), The Igntion switch for wear, are the black & black/white/orange connecting, the charge circuts could connect but perhaps the ignition does not ! (hence the n light comming on when kicked over). To discount the switch connect a wire from the connector in the l/h side panel, mag side not loom (black) directly to the coil (should be orange ) and see if you get a spark. you will have to either remove the fuel tank & seat to do this or put your hand up the frame (from the l/h side panel) in order to find the coil and its primary connection.

Regards Jim

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Hi Ian,

First off check that the ignition timming is correct .. this should be 1.8mm btdc as the points open, this should be done via a dial guage (to measure the piston back by 1.8mm) and a sensitive ohm meter to work out when the points open & close. but other things to look at ... the coil are the primary & secondary windings giving the correct read outs (I would not think this as the YB coil lives in a nice place), The Igntion switch for wear, are the black & black/white/orange connecting, the charge circuts could connect but perhaps the ignition does not ! (hence the n light comming on when kicked over). To discount the switch connect a wire from the connector in the l/h side panel, mag side not loom (black) directly to the coil (should be orange ) and see if you get a spark. you will have to either remove the fuel tank & seat to do this or put your hand up the frame (from the l/h side panel) in order to find the coil and its primary connection.

Regards Jim

Thanks Jim i have tried isolating the ignition switch with no sucess but i will try your other pieces of advice when i get a chance regards Ian

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