Motorcycle Repair: Probelm with static timing a shovel, woodruff key, cam lobe

Question
Last question Mike. THanks again for all your help. It is quite appreciated.

One thing you mentionned puzzled me:

the pin on the advance unit was installed backwards. There is a pin on it too and should fit one way. Can you indicate how that could be installed backwards please?

Also, is there a way that i am not aware of to determine if the gear on the cam has spun. When i look at the gear itself, i see that it is pressed fit on the cam and 'locked' in place using a woodruff key. Also, i see scribe marks on the gear itself aligned with the keyway. So this indicates it did not move, yet i may be wrong.

thanks

stephane



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Followup To
Question -
Great. I guess you did not recieve it. Ok here goes. Now, i tried to time my bike the exact way you described below. What happened was that, at full advance (point cam turned completely), the slots on the points plate are still not long enough. I am missing about 1/4 inch. At full advance, with the plate turned counter clockwise at its maximum, the points are sitting right in the middle of the cam lobe.

I know this is not rocket science. And i tried a bunch of times, using different methods.

Now, i have looked at the cam itself. I don't see evidence of a spun gear on the cam. The cam was installed as per specs using the dots to align with the breather gear and shaft. My advance unit is correctly installed on the cam (the shear pin prevents it from being installed wrong). The points are brand new. and the points cam is installed correctly (again, it only fits one way). So i am a bit lost. Now the bike starts fine. (4 kicks cold, 1 kick or so hot).

My questions to you are:

1. How much wear on the advance unit can throw my timing like that?
2. Have you seen something like this before?
3. If the bike runs strong, should i bring it in a shop to make sure i did not screw something up? BTW i doubt, because all the parts, cam, pinion gear, etc... all fit in one way. they can't be inverted right? All the parts hanging of the flywheel install one way right?  



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Followup To
Question -
Mike, sent you a follow-up question last week. Did you receive it?

stephane

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Followup To
Question -
Mike, having a problem here that i can't resolve.

I have a 78 fx 74 incher stock except for an A grind cam and super 'e'. I am running single plugs with points ignition.

My problem now is that i can't seem to time it properly. Let me explain.

Last year, the shear pin on the advance unit broke and left me stranded for a while. SO i replaced that and it was fine. Note here that when the engine was timed, the bolts holding the points place were smack in the middle of the slots.

Over the winter i tore into it for a much deserved engine rebuild. Had the bottom end rebuilt and such.

So this year, go to set my timing in the following manner:

1. on the compression stroke, i bring the advance mark in the hole (vertical line). right after tdc.

2. THen go over to the points (gapped at .018), turn the points cam to full advance.

3. then turn the plate until the points just start opening (on the left side of the small points cam lobe)

Now what is happening is that i can't turn my plate far enough for this. It seems that i need to lenghthen the slots about 1/2 inch. They were fine last year, but not this year?!?!?!?

SO i tore into the engine again. Re-installed the the cam again (timing marks aligned). Re-installed the advance unit (only fits one way on the cam because of the shear pin). redid everything and still the same.

What am i doing wrong Mike?

Thanks...

Stephane
Answer -
I an going list the steps that you need to do just so we are on the same page.

1. Slide the pushrod cover up on the front exhaust. Turn the motor until the front exhaust just closes.
2. Looking into the timing hole, watch for the timing mark. Should be a line in the flywheel. Put it in the center of the hole.
3. Set the points at .018
4. Rotate the points cam and lock it in
5.Rotate the timing plate counterclock ways
6. With a test light and the key switch on slowly rotate the timing plate just until the light comes on.
Now you should be set
Let me know if this works.
Good luck and happy riding
Mike
Answer -
Heres what I sent back. If you sent another question I never received it. Send it again and I will be glad to help you.
Mike
Answer -
The only times I have seen this happen is (1) cam was installed wrong, (2) cam gear slipped on shaft, or (3) the pin on the advance unit was installed backwards. There is a pin on it too and should fit one way.
The advance unit usually doesnt wear that much. What happens is the springs get weak or break.
Your right, the cam, pinion gear can only fit one way, but you can be off by a tooth on the cam so that would make a difference.
As to the bike running, the timing plate is only used to time the firing of the points. If the biek is running great right now you are not going to hurt anything.
Good luck and happy riding
Mike

Answer
The pin I was referring to is the one on the inside where the part that the points ride on can be installed wrong. If you look at it ther is a pin inside and the part which the points ride on has a flat on it. the flat goes to the pin. I have seen people put it on backwards and usually smach the pin.
As to the cam. Some cams have a keyway and some are just pressed in. I didnt know which one you had. Since you have the one with the keyway it cant more or the keyway would break.
One thing, which cam do you have? There is one that have three letters on it. They are on the face of the cam. One is"A", other is "R" and then there is a "O" I think it is made by Crane. The cam gear can be put in different positions on the cam.
Let me know
Mike