The patent office doesn't evaluate the merit of the invention???  Ooooops!  My bad.  

I didn't know that.  You learn something new every day.

When I left this saga back in August, I had a flat tire and suspected detonation.  The project had to go on hold until I could get a new tire.  My plan was to add more fuel, install a colder plug, try pulling out some ignition advance, and install a wide-band air fuel ratio (AFR) meter.  Now its time to report how all that worked out.

The DPR9EA spark plug worked fine.  No fouling problems.  The #66 main jet was a dog.  It killed acceleration.  So the 62 main jet went back in.  I still suspected that I might be hearing some spark knock, so I pulled off the alternator cover and modified the ignition pickup.  It’s not difficult, but it is humbug.  As previously mentioned, about the most you will get out of elongating the mount holes is 2°.   My calculations indicate that for every .051” you shift the pickup along the circumference of the rotor, you change the timing 1°.  That’s an important number because each time you adjust it you must tear off the alternator cover, so it’s good to have an idea how far to move it.  Guesswork here would suck.

Once I had the cover off, I fabricated a simple tool to establish the exact radial position of the pickup so I would be able to relocate it and verify that the air gap would not be altered.  It’s located 2.913” from the center of the stator.

Now it was time to modify the mount holes to allow the pickup to be moved.  Its highly magnetic, so as you are filing away at the holes, the filings want to get into every nook & cranny.  Also, the wires are permanently attached, so you have this bundle of alternator stator and mag pickup to juggle.  I made a little wood block setup to hold the pickup while I worked on it.  I used masking tape to keep the filings out of the nooks & crannies.

Depending on whether you want to advance or retard the timing, one hole gets elongated closer to the pickup body, and the other just gets opened up completely.

I put it back together and verified that the ignition timing was retarded about 2° by shooting it with my strobe light and special timing fixture.  It was now 0° BTDC at idle and 27° BTDC above 4000 RPM.  That looked good to me.  The spec for full advance is 30° BTDC.  I wanted less advance for two reasons.  First, the tight quench and increased compression require less advance because the mixture turbulence is improved.  That mandates less ignition lead and I had felt from the beginning that the engine would run better with less advance.  Second, I suspected it might be detonating and pulling advance out would improve that condition.

At this point, I had also installed an AEM wide band AFR system and was ready to get some good data.  After running the guts out of it in 1st thru 3rd gear, I could see that I did not have anything close to a lean condition.  It was running very good but I was still getting little noises and rattles.  I just couldn’t rule out detonation.

I figured I should kill it with kindness.  It had plenty of fuel, and I pulled out some advance, and the plug was certainly cold enough.  Let’s amp up the octane and see if the mysterious noise goes away.  I picked up a product called “Race Gas”.  It’s an additive that supposedly can increase the octane of pump gas from like 92 to 106.  I did a little research on the internet but mostly got stuff that looked like infomercials on the HotRod channel.  I talked with the guys at the local speed shop and they said the stuff is legit.  I also talked with some of our local import street racer crowd who are major big into boost, and some of them said it does the trick.  So, I bought a very expensive can of the stuff.  Any of you ever heard of it?

The tensioner was still extended exactly 18mm, right where I left it at the last inspection.  The 310 miles I had logged since then were brutal.  All sorts of 2nd gear 7500 rpm pulls, dozens of trips through the first three gears at WOT.  Five LSR runs all the way to 7K or more at WOT.  That thing was WOT at every opportunity.  I know the general consensus is that the short runs are toughest on the cam chain, but this uber high rpm stuff isn’t exactly pampering the thing.  I was very pleased to see the tensioner still at 18mm.  Very encouraging.

The drive and slack sides of the chain still have ample margin.

The S&S carburetor is dialed in as good as I’m gonna get it.  A bit rough around the edges, but certainly easy enough to live with.  The stock airbox (modified) and K&N filter are keepin up just fine.  The stock muffler (modified) and MAC 1.79” ID header are handling the exhaust chores admirably, and it’s still very quiet.  I have done a couple of additional mods to the muffler and I will update that post later.   The DR650 cam has proven to be the bargain of the century.  When you consider how big the carb and header are, and then look at the flat power curve, you must give at least half of the credit to the cam.  Of course, the bumped-up compression and tight quench deserve the other half.  The redline shows the souped-up Stage II head certainly flows plenty good.

I guess I will never feel comfortable with the high cranking pressure.  With this much compression, I will always feel the need to feed the beast enhanced fuel.  I plan to finish up the rest of the additive and then start planning to tear it down.  I want to try and dish the piston and find a cam that closes the intake closer to 50° ABDC.  I need to get the dynamic compression ration down to 9.2:1 (about 190 psi).  That way I could be completely comfortable with 92 octane E10.

For now, I think I will enjoy the little Savage just the way it is.  Have some fun with it.  Rip it up a bit.  Get a better feel for how well the cam drive holds up.  This project has been a lot of fun so far.  Hey, it’s a HotRod disguised as a mild-mannered reporter.  

Thanks so much for sharing the results of your hard work!
So, care to make any guesses as to HP increase by fixing the crank breather puking? Maybe I should ask that on the other page.