Timing Mark on Rotor Not at "T" Mark on Case When Pistons are TDC

[UncleBuck]

Well, many days later and... actually the key is there?

Here's how the whole thing lays out...

Pistons at TDC (or near as my McD's straw lets me find), key of crank is on the bottom, timing marks 180° out of sync. Index Pin on Cam is also straight down - not that I actually have an index pin...

Any suggestions onwhere to go from here? My first thought is to rotate the stator 180°, and see if I can work from there - but that seems like a giant leap down the path of foolishness.

 

[retiredgentleman]

Well, many days later and... actually the key is there?

Here's how the whole thing lays out...

Pistons at TDC (or near as my McD's straw lets me find), key of crank is on the bottom, timing marks 180° out of sync. Index Pin on Cam is also straight down - not that I actually have an index pin...

Any suggestions onwhere to go from here? My first thought is to rotate the stator 180°, and see if I can work from there - but that seems like a giant leap down the path of foolishness.

The timing mark on the rotor is fixed with respect to the keyway in the rotor. So, if the crankshaft and its key are at the bottom (6:00) , the timing mark cannot be 180 degrees out.

The only way that it could be 180 out of sync is if a PO took the rotor apart and re-phased it, which I fine most unlikely, but never say never.

Post a pic so we can see where the timing mark is.

 

[UncleBuck]

I've drawn in (previously) the T insharpie that lines up ith the timing mark on the rotor when the pistons are at TDC.

 

[Grinder]

Are both pistons up at the same time? Re-phased motor?

 

[retiredgentleman]

I've drawn in (previously) the T insharpie that lines up ith the timing mark on the rotor when the pistons are at TDC.

That rotor is not assembled correctly, if the engine is at TDC. As I just said, the keyway on the rotor does not allow the timing mark to be where your mark is.

A real puzzle for sure???

 

[UncleBuck]

Both pistons are TDC, as best I can estimate. It's not a 're-phased motor.

It makes me feel better that you're as mystified as me. No less frustrated, but somewhat better.

Posted via Mobile

 

[hmusket]

Here's a couple shots of a rotor to show the relationship of the keyway to the timing mark. The first is from the back side, keyway pointing down, timing mark around 7:00. From the front, Green pen pointing at keyway, timing mark around 5:00.

 

[UncleBuck]

Yep, definately 180° off...

As in your post, the straw points to the keyway at 6, with the timing notch at ~1030. The second shot shows the keyway at 6, with the straw pointing to the timing notch at ~130.

 

[hmusket]

As a guess, some previous owner might have taken the rotor off using a gear puller, separating the electrical part of the rotor from the tapered fitting, don't ask me how I know this can happen, and then it wasn't put back together properly.

Before proceeding any further, I would first test the resistance of the rotor, see if you get at least 5 ohms between the rings, to see if the rotor is worth salvaging.

 

[Nomadic]

The rotor could have been proper all along and the PO installed the cam with your pistons at BDC.
Install the Rotor a normal so your cam chain could be broken and reposition the cam.

 

[UncleBuck]

hmusket: I get about 6 to 7 ohms between the inner and outer rings.

Nomadic: I really don't thing the rotor is proper. Between hmusket's photos and every piece of literature saying the timing mark should line up with the "T" on the stator when the pistons are TDC, I'm convinced that my rotor is crooked.

I think the way to proceed is similar to punkskalar's instructions on how to install and time a PMA system (thread link in tech section of site, or earlier in this thread), by making a new timing mark on the rotor. I'll also proceed with installing a new 3mm pin in the cam shaft to lock the position of the advance rod. Once everything is locked to everything else mechanically all that's left is...

...something I probably haven't considered yet...

 

[retiredgentleman]

UncleBuck;

The picture you posted in post #12, points out a problem. Take a look at where the fly-weights mesh with the slotted disc of the ATU. You have a huge amount of clearance (wear) , which will cause the timing to be wider than normal (and bounce around), and could put a hole in a piston. Those ATU parts are worn out.....................don't run your bike with those parts.

You could buy new ATU parts, but if you plan to keep the bike for a while, I think you would be wise to buy a Pamco ignition with the E-advancer. That would eliminate the points and the ATU, and give much more accurate timing (not to mention a stronger spark with a new coil).

 

[5twins]

Well, that may or may not be. If the unit is really worn, the slash marks on the little advance rod disc and on the unit backing plate will be out of alignment. What you need to do is check the amount of advance the unit is giving you. With timing set correctly at idle (in the "F" range), rev the bike to 3K or so and check full advance. Make sure it's not going beyond the full advance slash mark. If it does then yes, your advance unit is worn. Now, you can compensate somewhat for this by retarding the idle timing which will retard the full advance as well. As long as you can keep full advance timing at or slightly below it's slash mark and can still get the idle timing in the "F" range, your advance unit is still OK.

 

[XSLeo]

I have three rotors right here by my keyboard. The way your pics show the timing mark to keyway look right.
With your pistons full up and the cam pin pointing straight up or down where is the key way on the crank? It should be pointing down.
Leo

 

[peanut]

I'm just trying to time mine at this precise moment so I'm following this thread with interest.

Can I just confirm ....
with the rotor TDC mark lined up with the T (TDC) mark on the stator the crankshaft rotor keyway should be at the bottom yes ?

if both pistons are at TDC surely it matters whether the pin on the camshaft points directly up at 12am or down at 6pm ?

Mine points directly up at 12am otherwise the cam lobes won't be in the right place no ?

In other words is the PO's camshaft on 180 deg out of phase ?

 

[UncleBuck]

5twins: I would love to be able to rev the engine to ANY RPMs right now. I happily look forward to using my timing light to check for full advance.

XSLeo: I'll check again when I get home from work, but my best summary is: pistons TDC, advance / cam pin 6 o'clock, crank / rotor key 6 o'clock.

peanut: check the timing link posted by 5twins earlier; pretty sure it says either 12 or 6 is okay for the cam / advance pin. GRAIN OF SALT: I AM CLEARLY NOT A GOOD SOURCE OF INFORMATION ON PROPER SETUP.

 

[XSLeo]

Both pistons move together. When both are up at TDC one cylinder is on the compression stroke, the other on the exhaust stroke.
If the pin hole is up the right cylinder is on compression. If pointing down the left side is on compression.
You can't get the cam 180 out. If lined up 180 out the pin will still point up or down. It will just fire the left cylinder instead of the right.
Leo

 

[peanut]

Both pistons move together. When both are up at TDC one cylinder is on the compression stroke, the other on the exhaust stroke.
If the pin hole is up the right cylinder is on compression. If pointing down the left side is on compression.
You can't get the cam 180 out. If lined up 180 out the pin will still point up or down. It will just fire the left cylinder instead of the right.
Leo

of course . Thanks for the explanation .
I'm used to engines having a set number 1 piston lol

 

[UncleBuck]

Well, the mold maker at work cut me a fine little 3mm by 6mm pin to key the advance into the rod.

Three kicks later, she's purring like the little vixen she is. Thanks for a fine end to a long frustrating summer, lads!