You can still time it without the engine running. First you need to mechanically "zero" it first by doing the following:
1. Remove #1 spark plug
2. Use a screw driver or even better a dial gauge and insert it into the plug hole on #1 cylinder. Rotate the flywheel by hand (if it is too hard you can also remove the rest of the spark plugs) and watch the screwdriver or dial gauge rise until you can tell the #1 piston is at TDC.
3. With #1 piston at TDC. verify the flywheel "zero" mark is perfectly aligned to the stationary marker.
4. Verify the throttle cam mark is also aligned with the carb's throttle linkage eccentric screw slot and the carbs' throttle valves (butterflies) are fully closed. You will need a flashlight to look into the bore of the carb to do this. Do not confuse the choke valve with the throttle valve that is located at the front of the carb while the throttle valve is way inside the bore. If the throttles are not fully closed you need to adjust the timing tower linkage rod, one that connects the tower shaft to the cam and also the eccentric screw.
5. Verify the idle screw located at the bottom of the timing tower is not pushing against the block but just barely touching.
At this point you are mechanically zero. The next step is to verify you are electrically zero. You will need a timing light (regular inductive type) and a second person to do this unless you have a remote starter.
1. Remove all spark plugs but keep the wire plugs connected and ensure they are all grounded. If you do not have a spark plug tester/ground kit, you can make one easily using copper wire wrapped to each spark plug threaded portion and connecting the copper wire to ground.
2. Connect the timing light to power and its sensor to the #1 plug wire
3. Aim the timing light at the flywheel and stationary timing mark.
4. With the control throttle in neutral, have a second person start or crank the engine. Note you are not trying to start the engine instead you just want to induce spark on #1 spark plug to check the timing. The timing should indicate zero degree on the flywheel. Usually, this is the single mark on the flywheel while the other markings next to each other are the WOT timing marks. If the timing is not at zero, adjust the timing rod. This is connected at the very top end of the tower shaft just behind the stationary timing mark. Continue doing this until the timing is at zero.
You are now mechanically and electrically zero'ed. However, while at it, you need to verify the WOT timing. And there are only a few steps more to do it.
5. Continuing from the above steps after verifying zero timing, place a small jumper wire across the interlock switch. This is usually located under the lower carb and has two wire connections. Place the jumper across these two wires.
6. Place the control throttle all the way forward in WOT position. Verify the carbs' throttles are full open. Again you need to verify these using a flashlight and looking into the carb's bore.
7. Aim the timing light to the stationary marker and have the second person crank the engine.
The timing should be set to 30 degrees. This is usually the middle mark amongst the three markings next to each other on the flywheel.
After setting the WOT timing, you need to set the idle screw for initial idle running settings. Turn the idle screw to push against the block so the carbs' throttles are slightly open. Note when you do this the cam's marking will not be aligned with the eccentric screw slot/marking anymore. And this is perfectly normal. Next set the carbs' fuel air mixture screws 1 1/8 ~1 1/4 out from slightly seated. Do this on both carbs.
Replace plugs, remove jumper wires and you are ready to do a test run. Post your results.
