Ignition Advance from sratch?

[Pinhead]

I'm in the process of rebuilding my '79 Honda CB650 SOHC 4-cylinder motorcycle. Redline is 10,500 rpm. I'll be running "Surface Turbulence" valves, cylinders, pistons (10.7:1static CR vs stock 9:1), and PowreLynz in the intakes.

In addition to these mods, I'm adding a programmable "Ignitech" ignition control module which allows me to tune vacuum advance for off-throttle performance and gas mileage in addition to WOT ignition advance.

The mods that I've added will substantially increase the burn rate compared to the stock motor. I don't have access to a dyno for tuning. :/

Where do I start??

[threepiston]

Sorry to say, bud, but Ping or Detonation... Then back it off at that RPM/Load table. That's all I have...

[Eric]

I cut piston grooves into a low compression water-cooled VW 1.8 and found that I had to drill holes into the distributor counter weights to even make it driveable.

[Pinhead]

I cut piston grooves into a low compression water-cooled VW 1.8 and found that I had to drill holes into the distributor counter weights to even make it driveable.

Which gave you more or less advance? What kind of grooves? Pics??

[Eric]

Much less centrifugal advance.
Star shaped design with the center of the star at the spark plug.
I see that the thread where I posted pics on this site are now missing, I can't remember how to post pics anymore, if you PM me your email I will send pics to you.
You might want to read this thread-
viewtopic.php?f=48&t=1253

[Eric]

Something I just remembered about that engine was that at one point after changing the timing belt I found that I had the cam timing off one tooth and there was almost no change in the way it ran. Usually it is quite obvious.

[Pinhead]

What exactly were the drivability issues that forced you to pull out the advance? Detonation? Bucking? No power? How many miles do you have on it now and is it still performing well?

[Eric]

When I had the timing adjusted so that it would idle ok it would ping like crazy as the rpms increased, when I dialed it back so that the pinging stopped it was so retarted at idle that it didn't even want to run.
I sold the car to a friend after I drove it for a year or so, she drove it for another year or so. An intermittent problem developed that I couldn't get to the bottom of, she decided to scrap the car (rust was getting to be an issue as well) She said I could have the engine if I wanted it. After stripping the car I pulled the engine only to find a cracked rotten vacuum hose underneath the intake manifold- the answer to that intermittent problem I'm sure
The engine is still in good shape and my friend says she really misses the power, she now drives a car with the same but unmodified engine.
I hope to do another piston grooved engine but my grooves were done by hand with a Dremel and were very crude, I would like to have the next set done with a milling machine if that's even possible.