Auto Timing Unit ATU

Hi Guys,

Starting a engine for the first time, checking the ignitiion for spark and timing.

Is there a chance that the ATU in the cam shaft be placed in 180 degrees out?

I'm getting not expected reading when looking at the points opening and closing.

Its hard see to the high spots on the ingintion cam.

Thanks
Crackers

Definitely. It happened to me too! I rebuilt the top end all to spec, points gapped and everything, points cam 180 out, kick and kick and kick, nothing. Pulled the cam, slid the pin a little more, turned, reinstalled, BAM fired right up. Good luck!

Hi

Thanks for the info.

Did you change the turn the internal shaft 180 degrees?

Or just the ignition cam 180 degrees?

Regards
Crackers

Try here;

http://www.xs650.com/forum/showthread.php?t=18187

Well, the ATU only fits to the cam one way. There is a pin that locates the ATU to the cam.
Now the disc that attaches the weights to the advance rod can be off. There is a line on the disc that should line up with a line on the ATU. This can throw the timing out 180.
On the advance rod there is a pin in each end, one for the ATU disc and one for the points cam. Both these pins should be pointing out the same side of the rod.
If one of these pins is pointing wrong the timing will be out 180.
If all the pins and ATU are set right the timing can still be out 180 on a points bike, the wires at the coils way be reversed. Where the wires to the points get plugged into the coils can be plugged in reversed this will throw the timing off 180.
Check to see that the wire from the top set of points goes to the coil that fire the right side plug, lower to the left.
One easy test is to swap the plug wires at the plugs.
Leo

Hi Guys,

Firstly happy christmas and happy new year.

I have now fixed the timing issue i had. the internal shaft inside the cam can be changed over by 180 degrees, i did this and throw the timing way out. The points are open for most of the ingination cam revolution and only close and open for a brief period before firing the ing coil. The points switch ground thru to each coil.

I now have another issue where i didn't have enough clearence to get the tiiming 100% correct. I had to file open the slots on the points baseplates to get more movement, so the points can be moved more around the cam.

Thanks for the help and info.

Regards
Cracker.

Generally if you need to cut extra room in the adjustment slots indicates the cam chain is worn.
As the cam chain wears it gets longer. This lets the cam timing get retarded. The more retarded the cam the more retarded the ignition. As this wear progresses, you get closer to the ends of the adjustment.
At this point you can cut the slots longer, this will keep it running, but it is better to replace the cam chain.
Leo

Hi Leo,

The cam chain is new, as is most of the engine. I was surprised i had to do this to get the timing ok, its not 100% perfect aligning on the F marks but is close enough, to run the engine smoothly enough for a 360 degree twin engine.

Regards
Crackers

Hey, Crackers61. Points cams DO wear out. Unfortunately, there's no surefire way to explain how to check them except to examine the wearing surface, and see if ignition timing, dwell, and gap setting are goofy. The amount of points follower travel is so small that a little wear on the entry ramp can lead to significant ignition retardation, even though it still looks fine. You could try the 'shotgun' approach and just replace it...

http://www.mikesxs.net/product/14-0656.html

Hi All,

Thanks for the help. I'll let everyone know how i go.

Thanks
Crackers