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TOPIC: Timing is Everything! How to do it on an RT1

Timing is Everything! How to do it on an RT1 05 May 2014 23:04 #1

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Your mileage may vary . . . (Original Write Up by DEET)

RT1B Ignition Timing

This is a general "How To" article. Please read through completely before attempting this at home!

Bring the piston to TDC (top dead center).

Back up the flywheel (rotate clockwise) to the proper measurement BTDC (before top dead center). In our case, it is 2.9mm.

Set the points to where they just open. You can use an ohm meter, or, if necessary, visually. The points can move after you tighten them down. Check it again.

Rotate the flywheel through a couple of cycles. Now, bring the flywheel around to where the points are supposed to open. Look at the points and make sure that they indeed open as the piston is heading to TDC.

Double check everything.









Some folks try to out-smart the Japanese engineers by adding slots to the stator backing plate. DO NOT DO THIS!



Those slots were put in by someone who was thinking they needed more adjustment in their timing.

If you remember the discussion about AC voltage in a different thread, voltage rises and falls depending on the position of the source coil to the spinning magnets on the flywheel.

So, the points need to open when there is voltage available to fire the coil and spark plug.

I think someone put those slots in there to adjust the timing beyond what was available in the stock form.

But, just because the points-to-source coil relationship has not changed, it doesn't mean you can spin the backing plate to any position. The flywheel is keyed to the crank and it must activate the ignition at a certain spot in relation to the piston position.

There is only one spot where the piston is at 2.9mm BTDC. Everything was designed in relation to that spot.

The flywheel has a cam ground on it that opens the points. The flywheel is keyed to a certain position on the crank.

How an ignition system works...

Here is how your ignition system works.

When the ignition key switch is off, the ignition circuit (primary side) is grounded. It grounds the black wire coming from the magneto. If you unplug all of the ignition switch wires, it can't ground the system. If troubleshooting a system, this will eliminate it as a cause of your problem.

The rotor has to spin to make power for the ignition circuit and the lighting circuit (they are electrically separate).

The points/condenser system is a standard (basic or Kettering) ignition system.

The rotor spins when you kick the engine over. This generates current for both systems (ignition and lighting).

While the points are closed, they allow current to flow to the primary (low voltage) side of the ignition coil which builds a magnetic field. This is the black wire coming from the magneto.

When the points open, the magnetic field collapses, forcing current to flow through the secondary (high voltage) side of the ignition coil where it is stepped up to several thousand volts. This amount of voltage will jump across the spark plug gap.

In doing so, a spark occurs. This will ignite the fuel/air mixture (if present) in the cylinder.

The condenser helps absorb the current that comes back to the points when the ignition coil magnetic field collapses. This keep the points from burning up.

Note that, at high rpms, the ignition coil may not have enough time to build up sufficient voltage to jump the gap... this can begin as a weak spark and then no spark. This limits the speed of your engine. (Or, so I've

You may find this procedure helpful....

Only turn the flywheel in one direction.... counter-clockwise.

DO NOT turn it clockwise during the setting of the timing until you are sure of the terminology.

Do not short-cut the instructions or turn the flywheel clockwise. OK?

Position the piston at TOP DEAD CENTER. The piston is at the top of the cylinder.

Connect your dial gauge and zero it for TOP DEAD CENTER (TDC).

Disconnect the stator black wire from the main wiring harness and connect one lead of your ohmmeter to the black wire and the other to the engine bare metal.

Here we go......

Turn the flywheel counter-clockwise slightly.... you are now in the "AFTER TOP DEAD CENTER" (ATDC) area.

Continue turning the flywheel counter-clockwise until the piston is at the bottom of the cylinder. The flywheel has now turned 180 degrees. You are now at BOTTOM DEAD CENTER (BDC).

Continue turning the flywheel counter-clockwise. You are now entering the BEFORE TOP DEAD CENTER (BTDC) area.

Continue turning the flywheel counter-clockwise until the piston is 2.9mm (or whatever your timing specification is) before it reaches Top Dead Center.

STOP.

This is where you adjust the timing.....this is where the points are just supposed to start opening...







Thanks for Following Along!
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Last Edit: by Makotosun.

Timing is Everything! How to do it on an RT1 06 May 2014 17:02 #2

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Awesome Detail- Thanks for posting this up! :)
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If it ain't smokin', it's broken!
1970 RT1 360
1970 RT1 360
1971 CT1 175
1971 DT1 250
1971 DT1 250
1971 RT1 360
1971 RT1 360 "Black Widow"
1974 DT 360
1976 IT 400
1978 XT 500
1980 YZ 465
1984 IT 490

Timing is Everything! How to do it on an RT1 06 May 2014 18:22 #3

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DEET gets the credit for the original writeup. I just transcribed and re-formatted it for here.

I have a few more in the works, but just need some time!
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