Finally i gave up on my overheating problen and took my 76 iron to a good buddy to solve the problem. I tried the intake leak tests and they were negative, along with the oil return which was fine. Not savvy enough to check timing, plus don't have a light, so paid $35.00 to find out the timing was off, which now i know is common, and needs to be checked often. So here is my question---Is there an easy way to check (and adjust the timing if needed) without a light. If so please share it with me. Also I am going to change oil, and have a good supply of 20/50 Harley oil I got at a garage sale for pennies. Is that weight oil O.K. to run in my bike. I live in Washington State a very moderate climate---Pls. let me know both answers------------------THKSSSSSSSSSSSSSSSSSS.

 

Check at Princess Auto or Harbor Freight. You should be able to get a timing light for less than $50, perhaps about $30 - about what you paid to have it done. Save your pennies, get a $100 one, use it 3 times and it has paid for itself. If you do get one [and IMO you should] post again here and i'll give you my specific instructions to use it.

That 20-50 HD oil is amoung the best. You can use it for both holes [although i prefer to use the HD Formula + for the primary].

 

My Indy took a sharpie and marked the timing plate and side wall to see if it "slipped". Been running Harley 20/50W for 17 years no problems in my 75 the Indy told me to do so.

 

O.K. I will take your advise as always, but once I have the light, what is the drill-Jeff

 

Setting The Ignition Timing on Your IronHead

1. Checking vs Setting the Ignition Timing

You can check the timing without changing anything. Changing the timing can be done by one person but is easier with two. The ignition module or points is on the right side of the bike, the timing hole is on the left side. Easier with one person on each side than to go back and forth. Standard advance for the 1980 XL is 40`. I have mine set at about 35`. At 38` i get pinging.

2. Equipment That You Need

You need an induction timing light which you can buy at any auto supply store. Best to get the "dial back" type. These allow you to set a number [like 35`] into the timing light and then adjust the ignition module/points backplate until you are there.

If you have very well insulated spark plug wires the timing light may not sense the signal thru the wire. If this is the case then open the gap on the spark plug to 050 or more. Reset it to your normal gap [030 for points or 040 for electronic] when done with this procedure.

It also helps to have a throttle lock as the timing should be checked/set with the engine at 2500 to 3000 RPM.

You will need a piece of rubber oil line hose about 1 inch long. Press one end up against the side of a stone grinding wheel [or whatever] to make sure it is perfectly flat.

3. Front Cylinder: TDC Mark vs Advance Timing Mark

The TDC [Top Dead Center] mark is used with a dial back timing light to check the timing, or to set the timing at a specific degree, such as 37`. The advance timing mark is used to set the timing to the factory setting, such as 40`. Best is to use a dial back timing light to check or set timing.

4. To Identify Your Front Cylinder TDC Timing Mark

Remove spark plugs. Rear wheel off the ground, shift to 2nd gear, rotate wheel until it clicks, repeat until you get to top gear. Now by rotating the rear wheel you are rotating the engine. Almost impossible with the plugs in; very difficult in lower gears.

You want the front cyl to be at TDC. You can see in thru the spark plug hole, especially with a flash light; you can try inserting something soft like a pencil and watch it rise and fall as you rotate the engine with the back wheel but be careful it does not break or get stuck! You will have to hang on to the pencil with left hand while rotating the rear wheel with the right. Helps to have a good wingspan, or an extra person.

With the piston at precisely TDC look in thru the timing hole. You should see a drilled dot or a line. That is your front cylinder TDC mark. Once you know for certain what the TDC mark looks like you can check the timing.

5. Procedure, Checking The Timing

Begin with the engine at operating temperature. Remove the timing plug from the left side of the engine. Insert the 1" hose smooth end first, right tight up against the flywheel. I use a needle nose plier and twist it in there as firmly as i can. If it is not smooth and tight against the flywheel oil will spray out while you are working.

Start the engine, have it at about 2500 to 3000 RPM [it will be extra noisy with the timing plug out], set the timing light at 40`, aim it into the timing hole thru the hose. Click it down one degree at a time while you look for the timing mark. If you don't find it you may have to work up from 40`.

If it is in the 35` to 40` range and there is no pinging then you may wish to leave it as is. With pinging on acceleration you may want to retard it by about 1/16 of an inch or less [see Math below].

6. Procedure, Setting the Timing

Remove the points cover from the right side. You will be rotating the back plate so first mark it so you can get back to the current position if needed. Make a scratch mark or use a permanent magic marker, or better still a small bright red or whatever color paint mark.

To change the timing loosen the two standoffs holding the points/ignition module and rotate the backplate. Clockwise advances [larger degree number] counter-clockwise retards [smaller degree number].

7. Some Math, How Much to Rotate

The backplate has a 3" diameter = 1.5" radius.
The circumference = 2 * pi * radius = 2 * 3.14 * 1.5 inches = 9.42 inches
The circumference = 9.42 * 16 ~= 151 sixteenths of an inch.

One rotation of the backplate corresponds to two rotations of the engine, so it is like a circle that has 2 * 360 = 720 degrees. 720 / 151 ~= 5

Therefore a rotation of the backplate by about 1/16 of an inch results in a timing change of almost 5 degrees!

 

Thank You, will buy a timing light as it looks as if I will need it as time goes on-Jeff

 

When i wrote those notes i had a dial-back timing light and i have not ever used a regular one. With a regular t light you can only set the timing to the factory spec and check to see if it is set there [40` for IronHeads]. With a dial-back light you can set/check at any setting.

A dial back light will cost more and for me it is worth the extra. If you cannot afford the extra then get a cheapie regular t light, set the timing to the factory spec 40`, and if it is too advanced [pinging heard] simply retard it by about 1/16th inch or so as explained at the end of the notes. You will not know at exactly what degrees it is set but many guys live with that.