Setting the timing on the points.

[Revvy Kevvy]

Damn, I thought this would be easy. I have set up contacts many times on cars. Find TDC, put a lightbulb over the contacts, turn the dizzy cap until the points open at 6 deg before TDC, light bulb goes on...easy.

Well, my XS400 she dont wonna start. I got new fuel, rebuild carburetta and spark. But I opened the contact box and the screws are loose so I thought the timing is wrong. But, setting this up is a absolute misery. Maybe there is a trick to this game?

Left side, set up the LF to the mark and now move the contacts around until the light bulb comes on. Ok, she is times but when I rotate further the contacts almost dont open so for a bout 3-4 hours I play trying to get a good opening of 0.3mm (0.012in) I can get one but not the other. Eventually I manage this game.

Right side, try to do the same, but its impossible. The timing spot seems to move, I get it nice and set up and then spin the motor 45deg back and return to the RF line and it dont work. At last I get it but not the contacts hardly open at all...after another 4 hours I give up. I ran out of beer...

The cam indent is so small I wonder if I have a worn out cam? but its not a high mileage bike (40K kilometers) but on a car the indents are much bigger. This one I can hardly feel.

Or is there a trick to get this to work, I did not expect any issues but its actually quite difficult to get a good contact opening and have the timing at the right place.

Maybe the solution is electronic ignition.....but I would like to get it working on these contacts I just cannot believe how difficult it is...the entire day used up and 12 beers and I cannot really say its timed correctly.

Even worse I dont know if this is the problem....

 

[tstidham]

I recall having some similar trouble and just used a Dremel to enlarge the slot in the points to get it timed.

 

[Revvy Kevvy]

Perfect, I will give this a go. I really get the feeling that the cam is too small, like its worn out.

Many years ago I bought a pontiac that just got slower and slower and after almost a million miles the cams had worn out and were not lifting the valves anymore. But, that car had score marks on the cam where it just wore out. I dont see them in this plus its only 30K miles on the bike.

Up until now I am usually a car owner, this my first bike since I was about 20yo. The timing is kinda same idea but different way of thinking.

Off to find my dremal....hopefully it will start after this.

 

[Revvy Kevvy]

Ok, its all timed so lets see how I did it.

1, open the inlet valve covers on Rh and LH sides.
2. turn anti clockwise until I see the LH valve open. Use my chop stick to test where is the piston. It should be going down.
3. Now I know its sucking fuel so the next up of the piston will be compression and normally bang.
4. use my chop stick to establish that I am now at TDC
5. look at the timing marks in the window and find TDC then LF fire mark.
6. use my bolt and spanner contraption to keep the position in the right spot. (see pictrue)
6. Put my light across the points and turn on the ignition. Test by putting a screwdriver across the points if the light goes off its all ok.
7. Adjust LHS using the gap adjustment and the timing adjustment so that the points open in the middle of the LF mark. Light goes on.
8 rotate roughly 30 degrees anti clock (the cam indent really covers a small area so you dont have to rotate much to find a high point)
9. remeasure the points gap, should be between 0.3 and 0.4 mm
10 move to the RHS
11 follow the same process like on LHS.
12 add some oil to the wick on the top of the assy.
13 Turn off the lights and see the points spark when I turn the engine.
14 reattach the spark plugs to leads and hold against side of engine to see spark...get a big shock doing this.
15 screw in spark plugs after cleaning and setting gap to 0.8mm

Tomorrow I will add some fuel to the carbies and hopefully this baby will fire up. Its been sitting in a barn just south of the artic circle for 25 years after just being parked and never ridden again. I had to rebuild the carbies as they were full of green sludge so that might be my next challange. Hopefully using the youtube tutorials I got it right. There is not much about setting the timing certainly nothing about making sure its on the correct stroke. Not in the book either, just some paragraph about static timing.

Once I have it going I will stick the timing light on it and see how easy it is to dynamic tune. I guess I have to loosten the big screws on the peripheries and rotate the assy while it runs. Seems a bit dangerous to me but I will look into this once the engine is actually ticking over and make some pictures of it. I see nothing on youtube about adjusting timing using a light while the engine is running but I guess the way I described is how it is done.