TDC marker and Ignition timing problems

650P · New Member Joined: Aug 15, 2006 Posts: 9

Hi all,
Im Writing to you from Sri Lanka. I have a 1977 XS650P (Police model)
I have posted a pic of it.

When I get the piston to TDC with the aid of a screw driver in the plug hole, the pointer on the generator does not line up with the "T" mark on the housing !!

Also even with the points plate turned to the fully retarded position, the ignition timing on the RH cylinder is too advanced.

The motor starts and runs... could it still be that the cam timing is out ? is that why I cant set my ignition timing correctly ?

What about the TDC marker isue ?

Please help !!

kingwj

I can see only one way the mark will not indicate TDC. The alternator rotor is not properly positioned on the crankshaft, maybe a missing key. I would think that would need to be sorted out before you worry too much about cam/crank alignment. A puller is needed to pull the rotor.

You can check cam alignment by setting the motor to true TDC (the start of the combustion stroke, not the intake stroke) and pulling the ignition advance unit. The locating pin for the advance should be at 12 o'clock.

650P · New Member Joined: Aug 15, 2006 Posts: 9

HI all,
I just found the issue with my Crank shaft TDC marker not lining up when the motor is at TDC.

Have a look at the attatched photos.

The "hub" of the crank rotor fits on splines to the rotor itself.
Someone, for some reason had pulled the hub out and fitted it back in the wrong position.
Thus, when the crank was at the TDC position the rotor itself complete with marker and all, was in the wrong position.

What Happened to 650rider.com?

Yamaha xs650