stumbling 120 evin

[kgw]

Hi guys,<br /> helping a friend with 88 ev. this motor stumbles at low rpm<br />putting timing light on all 4 cyls. one at a time light goes out when motor stumbles.<br />my question is if the motor stumbles for any other reason besides ignition would i still see the light go out because the flywheel also stumbled causing the stator to interupt voltage to the power pack ?<br /><br />its kind of like what came first the chicken or the egg<br /> thanks guys

 

[ob]

Re: stumbling 120 evin

I'm not sure I understand your description of the timing light test.Are you saying that the light would flicker in synch with the firing of the cylinders and then when the engine sputtered it didn't flicker at all?

 

[kgw]

Re: stumbling 120 evin

Hi OB,<br />yes thats exactly what happens .Light will flicker in sync with firing then go out when motor stumbles. happens on all four coils. I guess if I had 4 timing lights i could see if all four went out at the same time but I dont.<br />It only happens at 1500 rpm or lower. carbs,lynk & sync also done. thankss for reply.

 

[ob]

Re: stumbling 120 evin

If we could be sure that it is indeed dropping fire to all four then it helps to narrow down the intermittent failure.That eliminates the probability of all four coils.You will need to have the voltage output of the stator tested with engine running to see if it is the culprit.There are ohm figures but they aren't as reliable as an actual running test.If you have a good flashlite and a mechanics mirror ,you could get a good look at the stator windings under the flywheel and see if they are partially melting down as would be evident from any black goooey residue.That's just a quick visual check.Removal of the flywheel will reveal a better look.<br /><br />Charge coil from stator output is around 150 volts and the powerpack output to each coil is around 130 volts . Charge coil ohm range is between 430/530 ohms.If the stator output checks out OK and you have determined that you are losing spark to all four at low rpms ,then I would suspect a failing powerpack or ignition trigger issue.

 

[kgw]

Re: stumbling 120 evin

Thanks ob,<br />yes I agree with you I did pull flywheel,every thing looks clean and neat. I know ohms tests are not reliable,I am used to troubles on stators on harleys but they are only used for battery charging not ignit. and ive never seen one fail because of windings its always a burnt plug or broken wire.<br />I guess I'll have to get a cd vom. all I have is a very accurate digital/anolog with +/- peak hold feature. this prob is simular to a prob. i had with my 140 that turned out to be sloppy timer plate linkage.<br />Thanks again