Motorcycle Classics

Installing an Electronic Ignition

Follow along with this guide to installing an electronic ignition on a GS750.

Our project this issue is upgrading the ignition system on a 1977 Suzuki GS750 from points to Elektronik Sachse solid state ignition. Once done, we won’t have to worry about points and condensers any more and can just enjoy riding. This project is relatively simple, as you don’t have to disassemble anything more than the points assembly. A good set of metric wrenches and JIS screwdrivers are all you need to complete the project, along with wire crimpers and strippers, and some zip ties. — Keith Fellenstein

1. Our subject bike is up on the lift. It currently still sports the original-style points ignition. Not for long!

2. After disconnecting the battery, we’ll start the process by removing the points cover. Three Phillips type screws hold the cover on. This is a dry assembly, there should be no oil or fluid inside it.

3. With the cover off, remove the three screws holding the points plate in the engine. These are a combo Phillips/flat blade screw, but the Philips part was burred out beyond use, so I used a flat blade to remove them.

4. You may need a shot of penetrating oil to help with removing the nut holding the points cam in place.

5. A 12mm socket and wrench will remove the bolt holding the points cam in place.

6. Once the bolt is out you can remove the points plate and the timing plate behind it. You won’t use either of these anymore, so put them somewhere you can find them if you should for some reason want to convert back some day.

7. The points cam just lifts out. Store it with the other spare parts.

8. Now it’s time to remove the gas tank. It’s best to have an empty tank, but if you can’t empty it, make sure the petcock is not set to Prime. Disconnect the fuel hose from the tank and with a wrench and 12mm socket, remove the bolt at the back of the tank.

9. Wiggling the tank while pulling back on it will ease it off the rubber buffers at the front. Then you can lift it off and set it aside in a safe place.

10. The old coils still worked, but since we’re upgrading the ignition, we may as well upgrade the coils too.

11. We’re reusing the plug caps, so unscrew them and put them aside for now.

12. These resistor caps can get corroded and increase their resistance over time, so it’s a good idea to take them apart and clean them. Usually there’s a slot in the part that captures the thread at the top of the spark plug. Use a screwdriver to disassemble them as shown here.

13. It’s a good idea to make note of the cylinders the coils fire as a reminder for reassembly. Also note if the plug caps have different configurations for the inner cylinders.

14. Use a 10mm wrench to loosen the nuts holding the coils in place.

15. Notice the unused (for now) mounting holes on the frame bracket.

16. The new coils are shorter in length than the old coils, so we’ll make use of those other mounting holes.

17. Move the mounting bolts and stand offs from the old coils to the new coils.

18. Now the coils fit perfectly in the unused holes in the mounting bracket.

19. I could have just modified the wiring harness to fit the spade terminals on the new coils, but I hesitate to change the harness. I wouldn’t want to be called the DPO (Dreaded Prior Owner) when the next owner changes them again.

20. I didn’t have any wire that matched the original harness colors, so I made more notes to keep the circuits organized.

21. With the harness adapters wired in to the coils, it’s now time to mount them permanently.

22. After cleaning the resistor plug caps and trimming the high voltage wires, the plug caps are screwed back on. Getting a good connection here is key, and it will take some effort to get them started. Don’t forget to put the rubber end caps on the wires first.

23. The new pickup plate is a little oversized for the mounting location, so there will be some fitting required here.

24. I started off with emery cloth and a file, but soon moved on to a Dremel with a sanding drum to speed things up.

25. Now the sensor plate fits snugly enough, but can still be rotated for timing the ignition.

26. Place the new rotor stub on the end of the crankshaft, aligning the notch in the stub with the pin in the crank.

27. Center the pickup plate screws in the middle of the slots on the plate so you have room to fine tune the timing.

28. Slip the magnetic rotor over the rotor stub. Leave it loose for now.

29. Tighten the bolt that holds the stub to the crankshaft end. It’s a small bolt, so don’t overtighten it.

30. Find a suitable place to mount the black box ignition controller. We’re using some space behind the left side cover.

31. Trace the leads from the old points plate back to where they connect to the wiring harness and disconnect them.

32. Fish out the old leads that connect to the points plate and remove the old assembly.

33. The kit came with a round weatherproofing grommet for the points cover but we wanted to use the old fitted grommet, so we carefully slid it off the old harness.

34. It slid right on the new wiring for a neat appearance.

35. Here is the grommet fitted to the case with a nice, neat wiring arrangement.

36. Run the new ignition harness back through the places where the original harness ran, to the new ignition controller location.

37. Here they are, ready to connect to the new controller.

38. Connect the wires to the appropriate terminals on the new controller.

39. We had to make a couple of short jumpers to connect the controller to the main harness to the coils.

40. Finding a source of switched 12-volt power was easy, but getting a focused picture was not.

41. We crimped a lead to the switched 12v source and prepared to heat shrink some insulation over it.

42. After applying a little heat from a heat gun, we now have an insulated power connection.

43. Now it’s time to set the timing. Rotate the engine until the outer cylinders are at TDC. Turn on the ignition. Rotate the magnetic trigger until the LEDs just go out and lock the plate with the set screws.

44. Using the supplied Velcro tape, attach the controller to the space chosen for it. Replace all the parts you removed for access and enjoy your new maintenance free ignition system.

  • Published on Feb 3, 2021
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