Advanced advance questions

[1980 Special Twin]

I've become intimately familiar with the advance over the past few months as my old one crapped out into shards of metal and the process of replacing and timing a new one overlapped with jetting and tuning in an annoying way.
I have and use a timing light, although I have no tachometer so I can't necessarily do the job by the book. Not that a pipes-and-pods kick-only chopper is by the book.
My question is can you FEEL when the advance kicks in? For all of the work that I've done on the advance, I can only tell if the bike works or doesn't work. I can't feel if advancing or retarding it will make it run smoother, tighter, faster etc.
Is the advance entirely about timing by the light and tach with no wiggle room, or is it more artful like the carbs where you can tune it to perform to taste.

 

[Jim]

An incorrect advance (too much) can burn holes in pistons... not something you want to leave to "feel."
The main concern is full advance... which you check with a timing light. Rev the engine 'till the ignition stops advancing. That's full advance.

The manual calls for 40°. A fair amount of people, myself included, feel the bike's happier on our modern fuel blends at about 35-38° advance.

Where advance retards to at idle, so long as it's easy to start and doesn't kick back excessively, doesn't really matter.

The only other thing to check is that the advance curve is smooth and tracks with the increase of revs. In other words, doesn't hang or get jerky during engine acceleration to about 25-3500rpm.

 

[gggGary]

yup the marks should go smoothly back and forth retard to advance with throttle on offs.
If this is still points there will be SOME wander. but over all.

 

[Jan_P]

According to your name
1980 Special twin and USA you can have an electronic factory ignition .. I am not familiar with these
But have used after market Boyer Bransden that does not have so much possibilities

The stock old advance unit with springs and weights is less exact and can be adjusted other springs and service on the axle

As Jim has it in # 2

But strictly speaking if one is really into it the parameters is Intake / Exhaust / Jetting
And sometimes it just becomes right and you will notice it on acceleration

The best way forward is to perhaps ask the Carb Pros about jetting for your setup ( if it is not perfect already )if they have time and are kind enought set that up right.

Depending on driving style I had weak springs and it advanced quickly to max .And that worked stellar
I dont know to what angle .. Bike ran like a rocket .But it was weak on retarding so I had to leave the stock unit.
Back then I did not know that I should have lubricated the advance rod . But the bike ran perfect otherwise.

 

[1980 Special Twin]

ok thanks for the advanced advance advice! I have the carbs more or less set up, but I've chased advance problems through the carbs before and I wanted to make sure that didn't happen again as I go to smooth them out.

 

[1980 Special Twin]

Is there an electronic replacement for the mechanical weights and springs? That's what I thought Mike's e-advance is, but I think that's their version of the Pamco which I already have (from a wise PO) to replace the points (that I've never had to mess with).

 

[gggGary]

Yes e-advance, Boyer, Hoos racing powerdynamo.

 

[Jim]

You say your bike's an '80. Have a look under the left cover for the alternator and see if the TCI trigger is still there. Give us a pic if you're not sure. If it's there, there's a cheap and easy way to go electronic.