Mp08 coil

[nomad007]

1980 XS 650 special - TCI ignition stock rotor- Does MP 08 coil need to be grounded? I have attached pic of old coil whose wire fell out of coil as I uninstalled. It metered 2.8 primary. Is that the original Yamaha coil or after market? SO I am planning on replacing with MP08 and the one I removed had a ground wire on the screw closest to back tire . The EBAY MP08 coil metered 3.3 primary is that good enough. I don't know if I am doing this correctly but I could not get any reading measuring coil input to spark plug wire lead on either coil but measuring plug lead to plug lead on eBay mp08 I got 14.56. on 20k ohms. I am currently having a no start issue - hopefully this fixes. thanks Damon

 

[gggGary]

Knew before I looked at the pics a coil that mikes has notoriously sold for years.
I like accel 140403 coils but others @5twins report great results with the Honda MP08 coils

 

[nomad007]

Knew before I looked at the pics a coil that mikes has notoriously sold for years.
I like accel 140403 coils but others @5twins report great results with the Honda MP08 coils

Thanks gary . Does the MP08 need to be grounded ? or did they just make that for the aftermarket coil?

 

[gggGary]

They don't need to be grounded but for rfi issues, it won't hurt anything.
Primary has two leads. And secondary is also a loop through the two spark plugs. Why you HAVE to ground the plugs to the motor when testing or if one is removed from the head and run on the other cylinder

 

[5twins]

That ground wire you found on the rear coil mounting screw is from the main harness and has nothing to do with grounding the coil. It's the main harness ground and anything connected to the harness that needs a ground gets it from there. Yamaha just chose that rear coil mount as the spot to connect it to the frame. Make sure you re-connect it to the frame somewhere or you'll lose the ground for any component connected to the main harness that needs it. I moved it to the front coil mount when I installed my MP08 because there was more room there. Here's a link to a thread I did on my MP08 install .....

https://www.xs650.com/threads/honda-mp08-coil.55408/

 

[nomad007]

That ground wire you found on the rear coil mounting screw is from the main harness and has nothing to do with grounding the coil. It's the main harness ground and anything connected to the harness that needs a ground gets it from there. Yamaha just chose that rear coil mount as the spot to connect it to the frame. Make sure you re-connect it to the frame somewhere or you'll lose the ground for any component connected to the main harness that needs it. I moved it to the front coil mount when I installed my MP08 because there was more room there. Here's a link to a thread I did on my MP08 install .....

https://www.xs650.com/threads/honda-mp08-coil.55408/

Thank you - I have been studying that thread its awesome