Looking for ignition tune up specs for an 86 big twin. My clymer manual has some contradicting info in it as far as rpm to check at and total degrees of advance.....

I've never had a problem with the bike pinging under load but my spark plugs have a small amount of aluminum deposits on them so I better check it out.

 

Detonation usually appears as black specs way down on the porcelain. You'll need magnifying glass and a Factory Service Manual.... It's all in there...

 

I couldnt get a good picture of mine but this is identical to what mine look like.

 

What's the heat range of that plug? I see it's some after market. I think your running the wrong heat range.. put in a set of NGK BPR5ES11 and go from there.... Make sure it's not running lean.... It's it popping out the exhaust on deceleration?

 

That's just a pic I pulled off the internet to give you an idea of what the little aluminum ***** look like on mine. I'll try and get a good picture of my plugs tonight.

I just installed a s&s super e so I'm still dialing in the jetting. Currently running a .295 pilot 70 main and a 60 air bleed. No popping on decel so i think pilot is OK and the main feels good as well. Midrange is flat so I'm gonna try and go back to a 40 air bleed. I've put about 100 miles on and the base ring of the plug has decent color but the porcelains are still white.

Thanks for the help, I'll get some pictures up and see what you think.

 

O and I forgot to say I am running bpr5es-11 plugs

 

First picture is front cylinder, second is rear cylinder, and the third is a closeup of the silver specs on the electrode of the rear cylinder plug. These plugs probably only have 70-100 miles on them

 

Preignition/Detonation

Porcelain = the porcelain shows up preignition/detonation, it will not accurately reveal jetting/air/fuel ratios. To look for the first/beginning signs of detonation, search the white porcelain for tiny black specks or shiny specks of aluminum that have fused to the porcelain. When detonation occurs, part of the air/fuel mixture explodes instead of burning, the explosion is heard as a "metallic knock", this audible knock is the result of a sound shock-wave, this shock wave travels back and forth across the clearance volume "disrupting" the cooler boundary layer gases that cover the entire clearance volume area.

Info came from here:

http://www.wallaceracing.com/plug-reading-lm.html

And more good info here (lengthy but still good info):

https://honda-tech.com/forums/forced...2A%2A-3063102/

And I really like this diagram:

http://www.google.com/url?sa=t&rct=j...blUVpaBooLJ6nA

 

I think you need to list what's in your motor build and what ignition. Detonation is not always heard. .0295/70 is a good starting point. Do you know where the ignition is at?

 

Thanks for the links Yankee Dog, some real good info there.

internally the motor is stock aside from an s&s 508 cam. Running a s&s teardrop air cleaner, v&h 2into1 pro pipe, and stock ignition pickup and coil.

I've never touched the timing, so that's why I want to throw a light on it this weekend and check it out. I had the pickup out when I did the cam but all I did was mark the plate and throw it back in.....

What do I set the rpms at to check for the 35 degree mark on the flywheel?