MS880 - no spark with new coils

[Muddy42]

52 minutes ago, GarethM said:

Bulb probably won't even illuminate at 1200 ohms, or just blow it after going through the windings.

sorry I see what he was doing now.  Doh, ignore me.

[spudulike]

Right, the two pairings on this saw are : -

1) Flywheel 1124 400 1210 (Polymer flywheel) and Coil 1124 400 1301

2) Flywheel 1124 400 1201 (Solid Metal Flywheel) Coil 1124 400 1302

It would seem like you have No 2 as above so you should have the 1302 coil and from you saying that it has two mounting screws, it would sound like it is the correct coil. Worth checking the part codes though.

Firstly, learn what an Ohm is and how basic resistance works. The beeper on the average multimeter is measuring what electricians call continuity...that is pretty much zero to around 50 ohms. What you are measuring is the spur connection in your HT cap to the coil laminates or even the kill wire and that will be through the HT wire and then through a load of very thin copper wire windings so expect a reading of 1000 Ohms or more. This reading will need to be measured on the correct setting on your multimeter and if you get a reading, it means your spur and HT lead are correctly joined to the coil.

I once had a MS461 with no spark and did this measurement and got an open circuit reading so took the HT lead off the coil and it was badly corroded. I cleaned this up and bingo, I got a spark and a running machine saving the owner £££. It happens.

In your case, if the flywheel is good and the coil is good, you should get a spark especially if you have disconnected the kill circuit so the only components are the flywheel and the coil (gapped correctly) ....there is still the question of when the spark happens (ignition timing) but if the flywheel key is OK and the flywheel keyway is OK, it should be bob on.

[spudulike]

I do hate loose ends, It is a bit like watching 7 episodes of an Agatha Christie series and missing the last episode where all is revealed. Most unsatisfactory.