Homemade timing tool

From Moped Wiki
Jump to: navigation, search

This has been done before many times and i am not claiming to have invented any of this but i did take pictures. thanks to anyone whose posts and threads helped me make this thing

thanks to everyone who posted in this thread



homemade timing tool


  • hacksaw
  • bench grinder for bolt head
  • hammer
  • file


  • spark plug
  • metric bolt m8 (1.00 thread pitch 60 or 70 mm long i think. it was the longest one they had where the threads go the length of the bolt)
  • nut for said bolt
  • small spring (i will try and get more info on exacts of spring, maybe get the home depot part number or something.)
  • washer (with o.d. large enough to sit on top of spark plug part but small enough that you can still get a wrench over it)

How to gut the plug

you want the guts of the spark plug gone. The easiest way i have found is to put it in a vice and cut off the blue colored (i colored it, see pic) shoulder on the plug with a hacksaw:


you dont have to cut all the way through, just enough to get through the metal. turn and reapeat


plug with shoulder cut off


hacksaw off the ground electrode.


wack the center electrode with a hammer a few times and the guts should pop right out.


disassembled spark plug


clean up the spot where the ground electrode was and probably the top side too so the washer will sit flat




Ok, the hard part is over. Now you need to grind down the bolt head so it will fit into the spark plug hole. A nice rounded top on the bolt will help center the tool and improve accuracy.

pay attention to the length of the spring. If you have the spring compressed the distance between the bolt head and spark plug washer should be less then 20 mm. About 18mm is fine.. You still should have spring action around 24mm.

check out the washer with marks for tenths of a mm. you can make a circle on paper and the mark every 36 degrees around the circle. then connect the marks to the center of the circle. next place the washer in the center of the circle and transfer the marks to the washer with a dremel or a file. putting a zero or other distinctive sign on one of your marks on the washer will help you keep track of where you started to measure from. V shaped marks on opposite sides of the nut facing opposite ends will help with accuracy. The upside down marker acts as half way, and whichever way you put the nut on, one of the marks will be right side up.



  • Unscrew spark plug
  • Screw in tool (doesn't have to be torqued down just get it snug)
  • Rotate flywheel in direction of normal travel till you get near TDC (you will see the top of the bolt be pushed up)
  • Once you think you have TDC, screw in the nut till its just sitting on the washer.
  • Mark TDC on your flywheel lined up with engine case seam or other marker on case. Label with a T
  • You want to be able to feel the piston barely touching the bolt head but not moving it up and down at TDC.
  • Zero the washer on the mark on the nut and then back out the nut by hand how ever many mm you want to spark before TDC (each turn of the nut is 1mm)
  • Back the piston up by turning the flywheel the opposite direction of normal travel about a quarter turn then rotate flywheel back till the tool just touches the piston.
  • Make another mark on your flywheel at your case seam or wherever you chose to line the T mark up with. This second mark is the F (fire) mark. You want your points to open just as the F mark lines up with the mark on the case.