With the 6-pound stocker.  What was Newton’s first law?  A body at rest will remain at rest; a body in motion will remain in motion; unless acted upon……….  The flywheel law.

Break-in consisted of two-hundred miles to seat the rings.  I observed a few things during the break-in.

It ran a lot hotter than the Wiseco Flat-top engine.  It was especially evident at steady-state operation, like on the freeway.  Nothing to be alarmed about, but it runs hotter.  Cylinder head temps were in the 310°F to 340°F range, and oil temp was in the 190°F to 220°F range.

Fuel economy was significantly lower than the Wiseco Flat-top engine.  The stocker was getting about 57 mpg.

Vibration levels were low.  The mirrors were crystal clear between 3500 and 4500 rpm.

Noise levels were exceptionally low.  I used my iPad with the NIOSH app to check the decibels at 1300/3000/4000 rpm under the exact conditions used for my muffler shootout.  The box-stock Savage whispered 57/72/76 dB.  (typo DBM)

Mechanical noise was also much lower.  Clicking, tapping and slapping seemed significantly reduced from the levels I was hearing with the forged Wiseco pistons and bigger cams.

It ran a bit erratic.  Lot’s of afterfire, popping, KaBooms, etc.  Deceleration was horrible.  It was embarrassing.  Steady-state was OK and it had decent throttle response.  As expected, warmup was not pleasant.  At least it wasn’t surging.

It was anemic, consistent with a box-stock Savage.  Three years ago, I dynoed this thing when it was totally stock.  It pumped out a blistering 30.5 horsepower at 5300 rpm  (dead nuts on the factory rating).  So now, when I do the performance tests on the stocker, the timed runs should be a good representation of what a 30.5 HP Savage can do.

All that was left were the performance tests to see what this econo-cruiser could do.  The test plan was to do timed pulls in second, third and fifth gear.  Each pull would be performed in the same location (Secret DBM Closed-Course Test Track).

The second gear pulls are intended to get a feel for how the thing is running.  I start the pull about 3000 rpm and stop about 7500 rpm.  Then I review the video and use a stopwatch to time acceleration from 4000 rpm to 7000 rpm.  If the second gear pull isn’t clean, or if there’s a significant disparity (like grossly lean fuel mixture), no sense forging ahead with the taller gears.

The third gear pulls are a measure of all-out acceleration.  These pulls are much easier to time, and the stop-watch readings are consistent.  If there’s a change in performance, it’s obvious.  Start, stop and timing points are the same as the second gear pull.  Since it’s an all-out test, I crouch down out of the wind (get under the paint) to maximize the performance.

The fifth gear pulls are a measure of real-world performance.  I start the pull about 3000 rpm and stop about 6000 rpm.  Timing points are 3500 rpm to 5500 rpm (55 mph to 85 mph).  Like the third gear pulls, they are easy to time, and the stop-watch readings are consistent.   I sit straight up on the bike and barge through the wind, just like you would do if you were trying to pass an 18-wheeler.  I view this test as the most instructive.  I think it measures exactly what most of us are looking for.

Next stop (Part 2) is the airbox.  We’re going to free up a little airflow and add a bit of fuel to see how much performance lurks in the bowels of that black plastic mouse trap.  I think some of you will be surprised.

Once the airbox is optimized, we will focus on the exhaust system.
 
After the exhaust system, maybe the carburetor or possibly the flywheel.  Give me some feedback to help decide which one to test first.   One costs money, the other needs special tools.

I hope some of you find this project informative and can use the data I collect to help make decisions on your own project.  If you have suggestions or comments on my test methods, post a reply so we can discuss.   As mentioned earlier, if you have a particular component or modification that you would like to see included, let me know and we can collaborate.

Best regards, Mike

I'd like to see if a larger K&N than the RC1250 would have any effect. It might mean cutting the bar mating the 2 tank bolts.

Yes, I'm cheap, otherwise I would have done it already.

DBM, you appear to have more patience than I could ever muster. Love to read about all your experiments. From the immortal Burt Munro: 'sacrifices to the god of speed!'

Looking forward to seeing the airbox data
I have done the carb jetting and the dyna muffler  i also have done the exhaust header / head sleeve mod from Drag bike Mike and his rear pulley wobble fix   I am something of a fan !  All these mods have been improvements and made the bike run better

Fast, that's like saying "Just win a land war against Russia."
A 4 valve OHC 650 should be making 50 HP in even a mediocre state of tune. My guess is that Jesus Christ on a bet couldn't get 50 HP out of one.
If you read all the work DBM did to squeeze some HP out of these, it's anything but quick and easy.

Zipidachimp, I normally run a K&N RD0710 cylindrical filter.  It's 3.5" x 5".  It should have quite a bit more surface area than the RD1250 conical filter.  I will be including that mod in this project, but not until I get into a larger carburetor.  My airbox tests indicate that a larger filter probably won't do much for any setup using the stock carb.  We'll see. Thanks for suggesting a larger element.  It will certainly be on the list.

Hiko, I just finished up on the airbox tests.  Working on the report now. The results were fantastic.

Armen, you make a good point regarding the limits of our LS650 engine. I suspect the cylinder head is the culprit.  That's a very difficult component to alter.  A good friend of mine recently sent me some pics of a wind chime he made from an old piston & valves from a Honda CRF450.  I was impressed with the valves so I googled to find out the size. That engine uses 38mm intake valves.  Our LS uses 33mm intakes. The Honda has 200 cc less displacement but 5mm larger valves. Geeeeez!  You're right.  BIG horsepower is anything but quick & easy. But you can realize HUGE improvements in HP and drivability on the LS with modest investments of time & money.  That Honda redlines at 13,500. Just imagine how hard it would be to squeeze a few more ponies out of that thing.

Fastman, thanks for the suggestion regarding the cam vs flywheel. That's an interesting problem.  The flywheel requires a puller, special deep socket, and offest wrench.  I suspect a prudent shopper could probably find those tools on Amazon or eBay for about the price of a DR650 cam. You do the flywheel and you get to keep the tools for future projects. You do the cam and you get the benefit of the extended powerband, but you have to go a bit deeper into the engine.  It would be interesting to hear from some of the novices regarding which to tackle first.