Id do 72 main. If I remember right the RPM at 1,500 or a little above.
Put a big fan in front of the engine because if you do the timing light by yourself you will be there a while. The very slightest bump on the ignition will make the mark leave the window. The mark will come into the window ccw.

 

The one thing I missed was in 86 the stock cam that was used had either a 37 degree or 38 degree intake valve closing. The 508 Cam that you are currently running has a 25 degree closing. That's a 12 or 13 degrees difference and it definitely will make a huge difference in dynamic compression.... and on that note if you didn't bump your timing back it is very likely you are getting donation.

 

Just to point out to those who don`t know, Pre ignition and Detonation are completely different animals.

 

That would be correct Dan. Here's an article I found for those who don't fully understand the difference.....

https://www.savvyanalysis.com/articl...tionDetonation and Pre-Ignition

Mike Bush:"Often confused and misunderstood, these two abnormal combustion phenomena are as different as night and day."

 

Thanks for all the info guys.
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And yes that cam is set up to be real aggressive in the lower rpms. S&s advises against running 10:1 pistons with it because of how much it raises dynamic compression.

I'll throw the timing light on it this weekend and see where I stand, but regardless I'm going to knock it back a few degrees.

Do you think a couple degrees would make enough difference or should I try setting it back 5 and going from there?

 

3 is a good start.... it didn't look all that severe...

 

Thank you! I'll start there and keep an eye on my plugs.

 

So today I put my timing light on my bike and this is what I found. Initially I couldn't find any of the timing marks, so I went ahead and retarded it about 2.5 degrees (one hash mark).

After that I could see the tdc line on the crank at idle (850 rpm). But when I brought the rpms up to between 1500 and 1800 I couldn't for the life of me find the 35 degree dot.

​​​​​​I tried with and without the clear timing plug in and my timing light isnt very bright so maybe I just couldn't see that little dot......

Does 0 degrees at idle mean my baseline is on though?

 

Do you have a dial back light. If so, set it to 35* bring the rpm's up to 1200, voes connected and dial in the cam sensor till you see the tdc line and your good to go....

If you don't have a dial back light, at 1200 rpm you should see the 2 dots for the front cylinder. If not confirm adjust the cam sensor till you do.... and as always confirmthat the VOES is working properly.

 

So I went to check the voes with my ohm meter like you suggested and surprise surprise the wire was unhooked! No wonder nothing seemed to line up right.

I plugged it back in and the 35 degree mark lands right in the center of the hole.

I must have snagged the wire when I was fishing the choke cable down through the dash... The motor felt sluggish but I figured I just didn't have my carb dialed in right yet.

Thank you mmuch for the help!