After a few months of work, the ol’ ATC 90 is back in action. This was not a restoration, but rather a series of long-overdue repairs needed to get it operational again. Over the past few months, the following repairs were made:
- Rebuilt engine top-end with new intake and exhaust valves
- Honed cylinder (it was still within spec)
- Replaced muffler with aftermarket unit
- Replaced original ignition coil and condenser
- Replaced original ignition points
- Replaced starter recoil spring
- Replaced gaskets and O-rings where necessary
- Cleaned and lubricated the drive chain
- Replaced Hand Grips
- Replaced damaged headlight and chrome bezel with new/old stock parts
- Replaced worn kill switch with new/old stock replacement
- Replaced portion of wiring harness where rodent damage existed
- Changed engine oil
Once again, it starts easily. It’s just as fussy on pavement as it ever was, since this machine prefers loose ground. It’s been in the family for four decades and was deserving of some attention.
Back on the trail 
Still looks good 
New recoil spring (left) and broken spring (right) 
Recoil starter is back together 
Oscilloscope confirms magneto primary voltage 
New headlight and bezel (left) next to original at right 
New hand grips 
Worn intake valve at left next to new one at right 
New muffler is test-fit before the cylinder and head are installed
