How to set timing with no timing marks help

[Nervousnovice67]

Hi all, I have an 81 xs650 which I got in a trade. When I got the bike it needed a top end so my and a few friends rebuilt it. I put a new pamco ignition in the bike and an e advancer also.i got the pamco set and the bike fires up nice. Now I'm trying to set the timing with a timing light and there are no marks on the stator. At one point someone put an acw brand pma kit in the motor and didn't make any new timing marks. I have a blown motor with an original stator I could swap onto my bike and make new marks but I'm not sure f the woodruff key is still installed. Is there any other way to reference the marks?

 

[XSLeo]

Welcome to the forum.
You need to find TDC. You do this with a piston stop. Once you find TDC you put a mark on the new rotor pointing to the TDC mark on the left side engine case.
Now you can use your timing light. If your rotor nut is properly tightened it will hold the rotor in place.
Leo

 

[Nervousnovice67]

Are the plugs supposed to fire at tdc? I thought that they fire at the 15 degree mark.

 

[XSLeo]

Yes the plug fire at 15 BTDC. But you need the mark on the rotor to line up with the mark on the case at TDC. TDC is easy to find. 15 BTDC is much tougher.
Leo

 

[Nervousnovice67]

I'll set the marks and let you know what I find. Thanks for your help

 

[Nervousnovice67]

Leo, I marked tdc on the rotor an case and put the timing light on the rotor. It's firing way before tdc. I'm confused how do I know if it's firing when it should be if I don't have a 15 degree mark. Sorry if I'm coming across as a meat head, I'm still a newbie when it comes to these motors

 

[5twins]

Most put a degree wheel on the crank and make new marks for 15° and 40° BTDC (full advance). Well, on second thought, I'm giving people too much credit when I say "most". I should say "some". Most just hack these bikes all up and basically ruin them. They don't have the skills needed to build a motorcycle but that doesn't stop them from trying (and usually failing), lol.

 

[Nervousnovice67]

Yeah I read about using a degree wheel I'm going to give it a shot thanks for your help guys!!

 

[xsfreak]

If you have marked tdc use a adjustable timing light set to 15 btdc then just use the tdc mark to set timing

 

[Nervousnovice67]

Wow I didn't think of that! So simple it's genius thanks bud

 

[pamcopete]

If you have marked tdc use a adjustable timing light set to 15 btdc then just use the tdc mark to set timing

This doesn't always work with the wasted spark system on the XS650 which fires every 360 degrees of the crank unless the timing light has a setting for that arrangement. A conventional ignition system will fire every 720 degrees of crank rotation on each cylinder.

Most modern automobile ignition system are also wasted spark, so just be sure that the timing light supports that arrangement.

 

[aldo5468]

See pic - left side of notch corresponds to 40 degree full advance - do not go over

 

[Nervousnovice67]

Finnaly got her squared away this afternoon. It runs so smooth now thanks guys for your help I couldn't have done it alone!!