Stationary Indicator - Timing

Hi All,

I'm rebuilding the engine and have got to the stage in the rebuild where I must ensure the T on my timing cover aligns with the stationary indicator. The issue I have is that I have moved twice since I pulled the engine apart and now I can't find the bugger.

A couple of questions:

1) Anyone have a shot of the XJ900 correctly aligned?

2) From the parts manual this looks like a pretty basic metal tab. Is there anything more complex to this piece? If not, can it be fabbed or is it required at all? The centre of the screw would seem to represent the pointer - NOTE: I assume it is there for a reason, but thought why the hell not ask.

I plan on getting everything back out and reorgnised to try and find it this weekend, but thought it wouldn't hurt to run it past the experts.

Cheers,
oby

 

I think the main purpose of this tab is to make it easier to line the engine up at TDC when installing cams or a cam chain. I suppose it's also useful for verification of timing, but, since there's no timing adjustment, it's utility is pretty limited.

It's more useful on my bike since I'm using an aftermarket ignition system which is adjustable.

In general, no, I don't think you need it.

FWIW, here's a picture of the timing setup on an 82 XJ750:

 

It's a reference mark is all. To "properly" set it you have to use a dial indicator to find true TDC and then set the pointer in place. Then it's just used for cam chain tensioning, etc. No, it's not vital. Would I reinstall it? Yes, if possible.

 

After awhile. In some cases, a good long while. Some cases; never. You'll learn that you actually do need parts like the Crank Position Indicator.
Set at the Factory and sealed to indicate TDC when the Marks line-up; you need it for setting the timing and observing the angle on the Crankshaft to determine if the Engine is running within the degrees of advance its supposed too at varying RPM's.

If the Indicator gets loose or inadvertently bent; you need to reset it with the Number One Cylinder at Top Dead.

You need it when you do.
Best to have it when time calls.

 

Rick please help educate me. If you didn't take the cam apart would the timing ever change on these engines? If so what would cause it? Thanks

 

Unlike a lot of motors whose ignition runs off the camshaft these run right off the crank, so while messing with the cams COULD affect cam timing, it cannot affect ignition timing. A bad or flaky TCI box or failing pickup could throw the timing off and you would need the mark to "keep it honest" as Rick outlines above. Having a pointer for TDC, even on a motor with "fixed" ignition timing is not a bad thing. The factory manual explains to find TDC with a dial indicator and then set the pointer when doing a rebuild, to give a PRECISE indication of where TDC is for future reference.

 

Technically, because there is NO Mechanical Advance, the Timing does NOT Change.
Neither the Rotor, nor the Pick-up Coils move even a little bit. Therefore the Timing is FIXED.

What little bit the timing is electronically manipulated is within a small area marked-out on the Rotor.

 

Thanks guys

 

Thanks gentlemen. I'm still new to this game and while my intuition was that I can get by without it, I feel happier now I have your knowledge to back that up.

I don't doubt it'll show up as I get everything re-organised, I just wish I hadn't had to move and thus shift everything from it's previously organised state.

Cheers,
oby