Re: timing
Jason, You need to have it properly timed. Normally those dissy models are 1/2 toot off, however, this is compensated for by the max advance.
First set the #1 piston to TDC On the '72 there should be a timing mark on the upper cowl support. Now remove the dissy pulley cover. The cast arrow should point to the punch mark (or three marks) on the flywheel timing decal. if not adjust it till it does. Make it 1/2 tooth retarded if you are 1/2 tooth off.
Now put a timing light on #1, all other plugs removed, connected to their wires, taped together and grounded to the block. Crank the motor and advance the cold start until the timing light reads 4-6 degrees BTDC. This is idle pickup. Do not change the timing, but rotate the brass Throttle actuator on the dissy, until it just touches the top carb throttle arm. there are two small bolts that tighten the brass throttle actuator.
OK, Now advance the throttle to full, key on. You will not be able to crank the motor using the key, so you need to jumper the starter solenoid to make it crank. Put a jumper wire from the red batt cable on the solenoid to the small yellow wire's terminal on the solenoid. When the motor cranks, set the max timing to 21 degrees BTDC. Use the max spark advance screw on the dissy to make this adjustment.
BTW - The 30MPH speed is not likely related to spark advance, unless it is really far off.
