Confused about timing marks?

[joebgd]

I have been going threw threads on timing lights and timing. When I started I believed that retarded timing would show up on the timing light further to the left away from the tdc mark. Now I'm seeing sighted examples of the opposite. Where it's being stated as retarded but moving to the right closer to tdc.
I also thought that 15° was more retarded than 10° meaning that it sparks 15° before top dead center and that 10° meant it sparks 10° Btc so the timing is more advanced at 10°.
Idk maybe because it's late for me and I've been doing allot of reading, I am very confused. If someone can lay it out in simple terms I'd appreciate it. I thought it was simple until I started reading.
I might wake up and it makes sense but right now everything I thought I knew about timing is coming up backwards in my research.

 

[Jim]

The closer you are to TDC, the more retarded you are. TDC is 0° You can't get any more retarded than that.* The more you move away from that (BTDC) the more you fire "in advance" of TDC.
For our XS, when the mark on the rotor moves left, it's advancing. When it moves right, it's retarding.

* You can, but let's not go there. ALL engines I'm aware of fire BTDC.

 

[650Skull]

Another way to remember it, is, your engine runs clockwise. 12 o'clock is full advance...........when the timing light is going back away from 12 o'clock it is retarding..............toward 12 0'clock it is advancing

 

[Raymond]

TDC is 0° You can't get any more retarded than that.*

* You can, but let's not go there. ALL engines I'm aware of fire BTDC.

Knew a bloke who years ago had an NSU Quickly moped. Which had a manual advance/retard lever. You could retard the ignition all the way after TDC, sit on the saddle with bike on centre stand, peddle backwards and the little 2-stroke would start and run backwards.

He used to rock up at the local chip shop and challenge proper bikers - wiv 650 BSAs, Triumphs, etc - 'Bet you can't ride my bike!' They would hop on, give it a handful and fall off as it shot back'ards. Not something I ever saw meself but sounds like loadsa fun.

 

[joebgd]

I think I get it now. Retarding it is making it spark later closer to tdc and advanced is sooner therefore advanced, further from tdc. But do our xs engines run clock wise or ccw?

 

[650Skull]

Read the posts

 

[jpdevol]

CCW

 

[Raymond]

I think I get it now. Retarding it is making it spark later closer to tdc and advanced is sooner therefore advanced, further from tdc. But do our xs engines run clock wise or ccw?

Looking from the left, that is the timing marks side, the engine runs CCW. So looking at fixed points on the stator, the mark on the rotor will go past fully advanced, then fully retarded, then TDC.

Put a strobe on the engine as it runs, at idle the rotor mark is (or should be) next to retarded on the stator. Add a few revs, and the mark seems to move clockwise towards the advanced mark.

(Crossed in post with Skull and JP)

 

[jetmechmarty]

On OH cam engines, looking at the end of the crank on the left side, if the cam chain tensioner is on the back of the engine (to your right) it runs CW. A CCW running engine has the tensioner on the front (to your left).

Just a fun fact to aid in identifying direction of rotation.

 

[gggGary]

Another way to remember it, is, your engine runs clockwise. 12 o'clock is full advance...........when the timing light is going back away from 12 o'clock it is retarding..............toward 12 0'clock it is advancing

?????

 

[joebgd]

I get it now that's what I thought ccw, I totally get it now. Idk how that got mixed up in my head. Retarded sparks later advanced sparks earlier.
Ya I was confused by skull post not to mention when I first adjusted my rockers and cam chain I thought it ran cw. The engine (rotor) turns ccw when runnimg.
Thanks all.

 

[jpdevol]

?????

Well, OZ and all......ya know water goes down the drain backward there too. So I suppose 6 O'clock could be 12 O'clock if ya were upside down.

of course; I have much respect for Skull and our friends "down under"

 

[650Skull]

Ha ha ha, I don't know what I was thinking. In my defence

 

[Dom]

How usual is it for an engineer to be CCW?

 

[Jim]

How usual is it for an engineer to be CCW?

Engine CCW?
VW... Corvair. Off the top of my head those are the only two that spring to mind.
Can't think of any bike engines...

 

[jetmechmarty]

Engine CCW?
VW... Corvair. Off the top of my head those are the only two that spring to mind.
Can't think of any bike engines...

Yamaha XS1100

 

[jpdevol]

At the risk of being pedantic (recently learned vocabulary); all bike engines (excluding horizontal jobbies) rotate forward, it's just a matter of where the ignition rotor is located: RH = CW, LH =CCW

 

[jetmechmarty]

At the risk of being pedantic (recently learned vocabulary); all bike engines rotate forward, it's just a matter of where the ignition rotor is located: RH = CW, LH =CCW

Hmmm. The XS1100 has its ignition components on the left end of the crankshaft. The alternator is on the right. From the left side of the engine, the crankshaft rotates CCW. The cam chain tensioner is on the front of the engine. You're making me think to hard. Oh, another thing I need to do is replace my pickup coil wires on that bike, the Achilles heel of the XS11. I think this engine breaks your rule.

 

[gggGary]

On a chain final drive motorcycle, transverse crankshaft, two shaft transmission (most motorcycles), chain drive primary OR one intermediate gear between crankshaft and clutch; the rods will be facing forward on the power stroke. And that's the majority of motorcycles, it's physics.

 

[Jim]

Engine CCW?
VW... Corvair. Off the top of my head those are the only two that spring to mind.
Can't think of any bike engines...

Now I've stepped in it.... I was trying to answer what I though was a question of backwards engines.... only to go wrong myself...
Yes, almost all bike engines rotate CCW. VW and Corvair are examples of Clockwise engines...