Diff between 1984 ATC 70 versus 1985 ATC 70

[wpginterceptor]

I have a 1984 atc 70 with a stripped spark plug socket on the head.. I was able to pick up a used running 85 ATC 70.. what are the main differences between these?

considering swapping out the motor but if there are big differences then ill just swap the head out

Complete 1984 Atc 70, with a stripped spark plug.. picked up a 1985 Atc 70 motor. Whats differences between the two? shift pattern? etc

[ps2fixer]

Going off the manual, the 84 was a 3 speed, and the 85 was a 4 speed. Also the engine and rear sprockets were different number of teeth. The 85 has a 13T front and 36T rear while the 84 has a 14T front and 35T rear. Besides the transmission having an extra gear and the sprocket on the engine being 1 size smaller (lower geared), I don't see why the engine swap wouldn't work. I'm about 95% sure it will bolt right in, only fear I would have is the electroncis, but I think most/all of the atc 70s were the same or extremely similar.

I don't normally work with that atc70s, so if someone has experience, please verify if my statements are correct .

[briano]

Motor and everything is the same thing except for the shift pattern. Both are 4 speed but the 85 is upshift pattern, and the last year of the atc70.

[wpginterceptor]

so bolt right in? would you just swap the head or just swap the whole motor??

[briano]

If the 85 runs, just swap the whole motor. Very simple to do, now you will have to get used to the different shifting pattern. The wires will plug right in, they are both 4 speeds, and the gearing is the same on both.