Waste Spark + Timing Light

Hyde

Hyde

XS650 Addict
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Hey folks, yes still messing with the bike. It's a bit better but still no spot on. This is a question for those who may be familiar with that ancient tool known as a timing light.

Rotor is marked for TDC (PMA/CDI). It's a waste spark system so when I hit the rotor with a timing light (set to 0) I'm getting double lines about 10-12mm apart. Is there a way to account for this? Which would I take to be the true fire line or would I use the center point of the 2? With a waste spark setup (in my mind) this would double down on my RPM showing on the gun as well theoretically - is that correct? Really trying to iron this out and get my timing spot on and/or something I can work with close to proper. Thoughts?
 
Hi Hyde,
my thought? More of a question, really. What year bike is it and what exactly has been done to it's ignition?
About the RPM reading, tell the gadget that it's reading a 4 cylinder engine, eh?
 
Hey Fred, it's Hugh's PMA/CDI on an 82. I sent'em a note last night also asking the question but haven't heard back yet. Wanted to see if anyone here had experience with waste spark and a timing light causing the double reading. Don't think there's a way to config the number of cylinders on the gun. You can set advance and zero it out, that's about all.
 
Hmmmmm...that's a bit odd. I'm pretty sure that just about every timing light I've ever seen has a # of cylinders setting.
 
OK - then it must have multiple scales on the tach since if it is only sensing one spark per cycle.....

....hmmmmm, I have to sit and have a think about this.
 
My inductive timing light has only one switch, the trigger to fire the light... no tach, and no number of cylinders,
I bought it decades ago and it has been a "good o'l goodern" all these years !
I have NOT used it on the bike yet as I saw no point because I can't change the timing in it if I wanted to !
(83'xs650 Heritage Special) But..... But...I do want to change the timing a few degrees to compensate for the modern fuel....
4 degrees is what I've read, but is that advance or retard ? advance it 4 deg right ?
.....
Bob.....
 
Some timing lights can operate ok with both a negative or positive spark pulse. Some can't and read funny, such as intermittent flashing, and other erratic operation.
On a dual coil, one plug fires positive, the other negative. Try hooking the clamp of your timing light to the other plug wire.
Often on the clamp it is marked which side of the clamp should face the plug. If yours does try facing the marking both away and toward the plug. If no marking just imagine it has one and try swapping it around.
In one of these positions you should get a single flash to use.
Bob Kelly, On your stock TCI, mark around the pick ups with white out or something like that so you know where it was positioned. I think on your 83 Yamaha used regular screws to mount them. Earlier used special screws that when tightened the head popped off. If you have the earlier version, make a straight blade slot in the screws, Dremel tool or hack saw blade, and they should come out. Or carefully drill into the heads till the heads pop off. There should be enough screw left to grip with pliers and turn out. Replace with regular screws.
Reinstall the p[ick ups to the stock position. fire it up and check and set timing.
This tip was from XSJohn, A long time poster that passed away a few years back. He retarded the spark a few degrees to get better low to mid range performance, Where most of us actually can use it.
Leo
 
No one has spoken directly about why there are 2 timing indications.
With ignitions that are camshaft driven, there are 2 sets of points or 2 sets of magnet, and if the 2 are not exactly 180 degrees from each other, you can see 2 timing flashes.

However, this thread says its a CDI ignition, which is crank fired I believe. A crank fired ignition is triggered every 360 degrees, so there is only the one trigger point, not 2 as mentioned above. That 1 trigger point should be exactly the same every rotation.
Seeing 2 timing flashes, makes me suspect its due to it being a poor quality Chinese made product.
Does the PMA rotor have a keyway and use a woodruff key, so that the rotor cannot rotate on the crankshaft ??
 
Good point RG I was waiting for someone else to mention it because alot of people think I'm full of shit ! so I'll say it Now....
YOU Can't have 2 timing flashes ! because there is only one trigger ! Period..... if the light is flashing twice then its the light's problem
take the plug out or better , pull the spark plug lead and put another plug in it and ground it on the head and turn it over and see if you are getting 2 sparks per revolution, if you are something is bad wrong with the Pamco crap on there ! which wouldn't be new !
the more I see of these replacements the more I hate them ! they cause more guys more problems than Points ever have... setting the points once a year is no big deal ! why do you do that ? oh well, personal preferences I guess ! to each their own !
I have TCI on my machine and I can see the lure of not having to mess with the points , but come on , really once a year isn't that bad and you KNOW then that the timing is perfect ! .... and you don't have the worry of having to replace a Very expensive module if the TCI computer thing dies ! ..... the old ways weren't bad ! and the new way is very questionable !
......
my 2 coppers !
.....
Bob.........
 
Right then!
Hyde sez his XS650 is a 1982. As he's in Brampton ON presumably a Canadian market bike and that late in the production run it has to be a Special.
Which means it came with an alternator-mounted ignition trigger and a TCI to work it's dual-plugwire coil.
So WTF did he swap that out favour of a set of HHB's Mongolian Mystery Modules, eh?
 
my thoughts are if he's seeing 2 flashes the one closest to TDC is the one he should take as the true timing mark ( simply because the bike runs now so it must be fairly close) and I would disregard the other flash completely....
the timing should change as the engine revs up.... if it don't throw it away and go back to the original if the original doesn't work fix it yourself there is plenty of info on how to do that here !
......
Bob........
 
Last edited:
Hey gents, I'm just in a dead panic trying to get this thing ready for Freedom Machines this weekend, so the post was in a bit of haste. The engine flooding itself (see my Sanity check post) and not idling steady is causing the erratic timing flashes. When I can get it decently smooth holding the throttle a bit, the lines come together properly to form 1. Apologies for the un-necessary post and thank you all to those who did reply.

Now back to mounting those lent BS38's to see if the carbs are really the problem or if I need to hunt Hugh down
 
Thx Pete! The 38's got her running with a choke no problemo (third kick). Updated my Sanity Check post. Hugh was insistent there were carb problems, he was spot on. His CDI is shooting a solid line now and running smooth.

Now to figure out what in the bloody blue blazes is wrong with the 34's lol.
 

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