Setting the Ignition Timing (advance) on a Ducati Single


This article describes how to statically check and set the ignition timing on a Ducati Single with an automatic advance mechanism (sometimes called an automatic timing unit or ATU). No timing lights here, just how do it statically. This article does NOT tell you at what specification to set the timing; use your manual and other resources to determine where to set it. Different engines use different states of tune and modern gasoline often makes it necessary to set the timing differently than specified back in the 50’s and 60's. Research the timing settings for your engine and test any changes very carefully.

I wrote this page after struggling for quite a while trying to set the timing right on my freshly restored Mach 1. The manual seemed clear, but finding TDC and dealing with the automatic advance mechanism remained mysterious me. Hopefully, this page will save others some of the discovery work that I had to go through!

Often I am asked why I don’t use a timing light. Well, the Ducati single doesn’t come with an inscribed rotating pointer mark and it certainly is very hard to set up a pointer with a degree wheel behind it! The manual does describe a special pointer gadget that is now made of unobtanium and there is a mark on the case to match with the strobe. But that doesn’t allow you to actual determine the angle of advance nor does it let you tweak the advance to another particular degree setting.

Another thing people bring up is “dwell” and they are often fixated on the gap between the points. Dwell is the time that the ignition is turned on (the points are closed). It’s important to have adequate dwell time for enough current to build up to have a strong spark when the contacts open. “Dwell angle” is the number of degrees that the points are closed. On a Ducati single the points cam is ‘flat topped’. This means that the dwell angle is substantially controlled by the shape of the cam. Adjusting the points’ gap DOES effect where on the corner of the cam that the points open and close, but the bulk of the dwell angle is determined by the shape of the cam. Thus the dwell angle is pretty much ignored when adjusting the ignition timing on a Ducati single.


Disclaimer: Please Read This!

YOU CAN DAMAGE YOUR ENGINE DOING THIS! You could easily damage the top of the piston with the piston stop. Be VERY careful. Also, setting the timing wrong could cause detonation or other problems that could severely damage your engine. If you don’t know what you are doing, don’t attempt this! Any action you may take based on this information is at your own risk.

In other words, you can't blame me for info you get here!


What it says in the manual

These are the three pages that cover “Setting the Ignition Advance” in my official Ducati workshop manual. These are critical and are required reading. However, it doesn’t really cover things like how to find TDC, or how to check the timing with the automatic advance mechanism fully advanced. Thus this web page.

manualp1.jpg (62K) manualp2.jpg (170K) manualp3.jpg (203K) click on each page to enlarge.


Special tools that are required

Points Light: This is called an ‘indicator’ in the manual. This is a simple light, of the right voltage to use with your battery attached with about 0.5m of wire to alligator clips. This is hooked up to indicate when the points open and close.

pointslight.jpg (62K) click on picture to enlarge

Timing wheel: Sometimes called a degree wheel. This is a wheel with degrees marked on it that is attached to the end of the crank. Mine is just a plastic disc I purchased at a local shop with a bolt through it. This one has the degrees marked from 0 to 90 on both sides (TDC and BDC). Thus you must be careful not to confuse the halves. I use a couple locknuts on the bolt to hold the disc in place so that it won’t spin accidentally, but can still be rotated. The bolt screws into the end of the crank and I use a contraption that I refuse to describe to hold it locked in place. This is sloppy, as one designed for the bike would lock into the notch on the end of the crack so that it cannot rotate; if you can find one of these, it’s worth buying it! There is a site on the internet that has a disc you can download, print and glue to your own rigid disc: downloadable degree wheel. The points light is also shown in this photo. In this picture you can see that the points are closed (because the light is illuminated) and that the crank is positioned at 37.5 degrees before TDC (read the wheel at the pointer).

timingwheel.jpg (59K) click on picture to enlarge

Piston Stop: The piston stop is used to find Top Dead Center (TDC). Note the hole through it’s axis so that so that air can pass through it: this is important. I bought mine here, but there may be better ones out there. Mine wiggles a little, and this can be a problem in getting consistent measurements. Search the web for “piston stop”, there are lots available.

pistonstop.jpg (21K) click on picture to enlarge

Advance Holding Washer: This is a conical washer that is used to hold the automatic advance mechanism in the fully advanced position. I made this from a normal washer that I hammered into shape (I placed it on top of a socket and whacked the center down with something.) The dimensions of mine are approximately: Outside diameter = 12.5mm, Inside Diameter = 6.0mm, Height 3.0mm, Thickness of the material = 1.0mm.

advwasher.jpg (14K) click on picture to enlarge

Feeler Gauges (leaf style): This tool is commonly available and is a set of thin sheets of metal in marked thicknesses. Get one marked in metric as well as English units. Make sure it includes several leaves sized inside the specification you need to measure as well as ones sized on the edges outside the specification. This allows you to precisely determine the setting within the specification.

feeler (1K)


Getting Set Up

First Steps

-    Remove the spark plug.

-    Remove the cap covering the crankshaft end.

-    Attach timing wheel apparatus.

-    Attach a piece of wire that points to the marks on the timing wheel so you can read the degrees accurately. I use a piece of safety wire screwed to the clutch inspection cover.

-    Remove the points cover.

-    Disconnect the points wire so that the points are not grounded through the coil, magneto/alternator or the ignition switch. (This will allow only the points closing to light the points light.

-    Hook one end of the points light to the hot side of the battery and the other end to the points as shown:
attachlight.jpg (21K) click on picture to enlarge

Find Top Dead Center (TDC)

-    Put the bike in top gear.

-    Rotate the rear wheel in the forward direction while looking in the hole to see when the piston is coming up. (Note, if you have a fancy timing wheel attached to a gizmo that allows you to turn over the engine right from the crank, you should leave the bike in neutral and just rotate the crank.)

-    Put your finger in the spark plug hole, plugging it. If you can feel/hear pressure as the piston rises, you have found the compression stroke. If it’s sucking, you need to spin the engine around past the intake stroke to the next compression stroke.

-    Find the top of the compression stroke visually, where the piston looks like it’s at the very top, and stop there. Move the timing wheel (without turning the engine) so that it is at the 0 position. This is just a rough starting point.

Next, find exact TDC with the piston stop. This involves using the piston stop to carefully and gently stop the piston on both sides (forward and reverse rotation) of TDC. Note both of these positions on the degree wheel: the exact middle of these positions is TDC.

-    Back the engine off (rotate it in reverse) about 40 degrees. Screw in the piston stop till it hits the top of the piston. GENTLY, VERY GENTLY! EVERY TIME YOU MAKE THE PISTON CONTACT THE STOP, BE GENTLE! You don’t want to damage that piston! It’s very easy to damage the piston by slamming it into the piston stop: don’t do it! Be careful! Back off the engine a bit more and then turn in back into firm (but gentle) contact with the piston. Note the angle of the degree wheel. I’ll call this position “A”.

-    Back off the engine all theway around in reverse until you gently, carefully and firmly come in contact with the piston stop again. Note this position “B”.

-    The location exactly in the middle of A and B is TDC. Adjust the degree wheel (without turning the engine) so that it is repositioned with 0 exactly at TDC. (You could just exercise math or mark up the degree wheel instead of repositioning the degree wheel, but I think this ends up being harder in the long run.)

-    Redo the whole rotation thing with the piston stop. If you have it just right, the stop will contact the piston exactly the same number of degrees both before and after TDC. This might take some “successive approximation”.

-    Note that you should set the piston stop so that you have a significant angle from TDC when you contact the stop (I use about 40 degrees). If you use a small angle, you will not be able to find TDC accurately, because the piston moves only a short distance for each degree near TDC.

-    With my tools this is a somewhat error prone process. Maybe the wire I use as an indicator moves or maybe the piston stop wiggles a little. Or maybe I contact the piston more gently in one direction than the other. Or maybe I’ve just been sloppy. But regardless, I have to rotate the engine back and forth, CAREFULLY, checking and resetting before I have TDC just right. In my experience, there just seems to be about +/- 0.5 degrees of slop in the system. Additionally, I need to recheck top dead center as I go along with the rest of the timing process. If the timing wheel slips out of position, everything else ends up wrong. Get the wheel set right, as everything else depends on this. If you can’t find exact TDC consistently, don’t bother going further. The timing does need to be set to the right degree!

-    Remember to remove the piston stop before proceeding!

(As a side note, some people use a dial gauge inserted into the spark plug hole to find TDC. A dial gauge is relatively expensive, and it’s hard to find one with the right attachments to use in the spark plug hole. But perhaps more importantly, it is said to be a less accurate method. The piston moves only a very small distance for each degree of rotation near top dead center and thus measurements there are hard to make. The piston stop method as described above works at a substantial angle from TDC where the piston moves a significant distance for each degree, and is thus an easier way to find TDC accurately.


Checking the Timing

Check the static ignition timing (with the automatic advance mechanism in the ‘engine still’ position; fully retarded)

-    Rotate the engine to about 60 degrees before TDC.

-    The points light should be illuminated. The points should be closed at this position and the light should indicate this. If it doesn’t, fix it.

-    Rotate the engine in the forward direction until the light goes out: Rotate the engine VERY slowly (like 1 degree a second) to see exactly where the light goes out. This should happen between 45 degrees before TDC and TDC (0 degrees). Exactly where depends on your bike and the automatic advance mechanism installed, if any. Check the manual for the specification. Note the angle: this is the Static Advance (without any automatic advancement.)

-    If the light never goes out and you can visually see that the points have opened; it’s either hooked up wrong or perhaps the circuit is being completed through the coil, magneto/alternator or the ignition switch. See the Set the stage section earlier. Fix it and try again.

-    If you don’t have an automatic advance mechanism, that’s it. Check your advance against the specification, and adjust it as necessary or as you see fit.

-    If you have an automatic advance mechanism, DON’T ADJUST ANYTHING YET!

Check the static ignition timing with the automatic advance mechanism FULLY ADVANCED.

Time for the magic washer! Fabricate an Advance Holding Washer. This washer is used to hold the automatic advance in the fully advanced position.

-    Take out the screw in the middle of the timing cam. Don’t loose the little washer. Put the Advance Holding Washer under the little washer. Use a pair of pliers (don’t scratch the cam surfaces!) to hold the cam fully advanced and tighten the screw.

-    Here I am holding the automatic advance mechanism in the fully advance position while tightening the advance holding washer.
attachwasher.jpg (79K) click on picture to enlarge

-    Rotate the engine to about 60 degrees before TDC.

-    The points light should be illuminated.

-    Rotate the engine in the forward direction until the light goes out: Rotate the engine VERY slowly (like 1 degree a second) to see exactly where the light goes out.  This should happen at a greater angle than before you forced the mechanism to fully advanced with the magic washer: that’s what the automatic advance mechanism does! Exactly what angle depends on your engine. Check the manual for the specification. Note the angle: this is the Static Advance WITH FULL ADVANCEMENT FROM THE AUTOMATIC ADVANCE MECHANISM.

-    At this point I loosen the advance holding washer and then tighten it back in place while holding the mechanism fully advanced again and then redo the check. If you are doing this right and the mechanism is fully advance you should get the same measurement. If not… you need to figure out what you are doing wrong. Remember, you are trying to get this right within a degree!

-    Note that the difference between the fully advanced timing and the timing without the automatic advance mechanism rotated should be the full range of motion for your advance mechanism. The manual should have this specification, and you should check it.

-    This would be a very good time to verify that your timing wheel is still perfectly set to 0=TDC. If it checks out, your earlier timing measurements are correct. If not, start over!

Congratulations, you now know where your timing is currently set! If it is set right, just remove that advance holding washer, put everything back together and you are done. Next, adjusting the timing…


Adjusting the Ignition Timing

Checking and Setting the Points Gap

The points gap needs to be checked to insure that the points fully open and close as they follow the cam. The Ducati single has a timing cam that has a high point that is constant radius,not a point. I call this top of the cam the ‘plateau’ of the cam. Adjusting the points’ gap DOES effect where on the edge of that plateau (sometimes called the ‘corner’ of the cam) that the points open and close, but the points are held open for the entire top of the cam’s plateau. Note that on top of the ‘plateau’ the gap stays approximately the same.

It helps to check and clean the points before adjusting them. Slide a white business card through the points to clean them. If the contact surfaces are rough, it’s time to replace the points.

-    Rotate the engine so that the points are open. Examine the position of the cam and set the cam to the approximate middle of the ‘plateau’. Measure the gap with your feeler gauges (leaf style) and adjust it if necessary (see your manual for the specification). I suggest rotating the engine a little and double checking the gap at a couple of positions on the ‘plateau’ just to be sure.

-    Using feeler gauges: Many people don’t get this right. Remember, the points are on a spring; you can force them wider and get an incorrect measurement! Feeler gauges require that you FEEL how they fit. The specification for my bike is between 0.3 and 0.4 mm. Say you want to set the gap to 0.356mm. This means you set the gap so that the 0.356mm gauge will slide effortlessly and frictionlessly through the gap. It literally can fall through. But while the 0.356mm gauge slides through frictionlessly, the next larger gauge must have friction or not fit between the gap. Thus you determine that the gap is actually somewhere between 0.356mm and the next larger size gauge. This also illustrates the importance of having many gauges within the specification. If your next larger gauge is 0.500mm, you really can’t tell if you have set the gap within specification! My next larger gauge is 0.381mm. So I know I have set the gap between 0.356 and 0.381mm, a range of 0.025mm. Personally, I like setting the gap this accurately, but it may not really be necessary to set it this finely as long as you set it within your engine’s specification. And remember the setting does vary slightly across the top of the cams plateau.

-    Adjusting the points: On the Ducati single this is harder than it sounds. There is a lot of slop in the mechanism and the gap does change when you loosen and tighten the screw that holds the points in place. It just takes much trial and error and soft nudging. And again, remember the setting will vary a little across the top of the cam’s plateau.

-    After setting the points’gap, I check the gap at a couple points near the center of the cam’s plateau. Usually there is a small variation, but not much. It’s just an easy and good double check.

Set the ignition timing with the automatic advance mechanism FULLY ADVANCED

I set the ignition timing with the automatic advance mechanism fully advanced and then let it fall wherever it lands when the automatic advance mechanism isn’t fully active (although I do check it there too, see the next step). The fully advanced position is where the system works at high revs where it’s most important. The unadvanced position really just makes for easier starting.

-    If you are following this procedure in order, the advance holding washer should still be in place. If not, put it back in by following the directions from earlier.

-    There are a couple of screws that when loosened allow you to rotate the entire automatic advance mechanism a couple degrees. Do NOT accidentally loosen the points! And be careful not to jostle the points gap that you just carefully set!

So this is a process (some might say ordeal!) of rotating the mechanism a nudge, tightening it firmly in place and then checking the timing again. Over and over till it is set just right!

-    a) Loosen the screws holding the automatic advance mechanism in place and rotate it just the slightest bit in the direction required to properly adjust your timing (see the manual). Tighten the screws firmly.

-    b) Rotate the engine to about 60 degrees before TDC.

-    c) The points light should be illuminated.

-    d) Rotate the engine in the forward direction until the light goes out: Rotate the engine VERY slowly (like 1 degree a second) to see exactly where the light goes out. This should happen between 45 degrees before TDC and TDC (0 degrees). Exactly where depends on your bike. Check the manual for the specification. Note the new angle.

-    REPEAT a-d until you have the timing set just right!

-    Now would again be a very good time to verify that your timing wheel is still perfectly set to 0=TDC.

-    And you might want to check that the advance holding washer really has the advancer fully advanced.

-    If you have the ignition timing set to your desired specification and your timing wheel is still perfectly set to 0=TDC and the automatic advance mechanism is forced to full advance, you are close to done.

-    Remove the advance holding washer. Don’t forget!

Check the static ignition timing (with the automatic advance mechanism in the ‘engine still’ position; fully retarded)

With the advance holding washer removed, you can now check the ignition timing with the automatic advance mechanism fully retarded. Since you changed the setting with the mechanism fully advanced this setting will have also changed. You should check it to make sure it also meets specification.

-    Make sure the advance holding washer has been removed and the screw with it’s regular little washer replaced.

-    Rotate the engine to about 60 degrees before TDC.

-    The points light should be illuminated.

-    Rotate the engine in the forward direction until the light goes out: Rotate the engine VERY slowly (like 1 degree a second) to see exactly where the light goes out. This should happen at a smaller angle than when the automatic advance mechanism was fully advanced.  Note the angle: this is the static ignition advance (without any automatic advancement.)

-    As I mentioned earlier, the difference between the ‘engine still’ timing angle and the timing with the automatic advance mechanism fully advanced should be the full range of motion for your advance mechanism. The manual should have this specification and you can (and should) check it.

Almost finished!

-    Put everything back together.

-    Clean up your tools.

IF YOU HAVE MADE ANY SIGNIFICANT CHANGES TO THE IGNITION TIMING YOU SHOULD TEST THE ENGINE VERY CAREFULLY. INCORRECT IGNITION ADVANCE SETTINGS CAN CAUSE DETONATION OR OTHER PROBLEMS AND CAN DAMAGE THE ENGINE!

WOO HOO! You are done! Put everything back together and go for a test ride!


Last Modified: 4/2/03


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