How to set timming on 1973 iron head v-twin - XLH 1000 Sportster Harley Davidson Motorcycles

To set the timing on our Ironhead, Take the spark plugs out of the engine, get the rear wheel off the ground, and remove the timing plug from the left side cases. Shift the transmission into fourth gear.

Using a plastic drinking straw, (do not use anything else because if whatever you use breaks, you'll have to pull the head to get it out. The drinking straw will not break or damage the piston), inserted into the front cylinder spark plug hole, rotate the rear wheel in the normal running direction until the piston comes up to Top Dead Center. Look in the timing hole and you should see a vertical line in the middle of the hole or there about. If not, rock the rear wheel forwards and backwards a bit until you find it. This is the TDC mark.

Then, start backing the rear wheel up until you see a "dot". This is the "Front Cylinder Advanced Timing Mark". This is what you want to set your timing to. Connect a timing light to the front cylinder.

To check the timing, shift the transmission back into neutral and lower the rear wheel. Install the spark plugs and temporarily install the timing plug. Start the engine and let it warm up just a bit. Then bring the engine to a high idle of 2000-2500 RPM, remove the timing plug, and shine the light into the hole. You should see the dot in the center of the timing hole. Caution: there is a mist of oil that will blow out of the timing hole. Do not let it blow into your eyes. Cover the timing light end with a plastic sandwich bag or something. H-D makes a clear plastic plug but it's not much good. A "Clean & Time" plug works good but you'll have to order one from one of the aftermarket companies.

To change the setting of the timing, remove the cover from the timer cavity on the right side of the engine. Loosen the hold downs on the timing sensor plate and rotate the plate slightly. Rotating it clockwise advances the timing making the timing mark move towards the rear of the timing mark hole. Counterclockwise moves the dot towards the front of the timing hole.

Good Luck
Steve