This completes the cam shaft portion of the project.  The DR650 cam worked great.  It was easy to install, a true bolt-in.  No machining, no special tools.

Let’s take a look at the results using test data from the stock header setup (keeping the project simple &  cheap).  The setup includes a mostly stock engine, stock bore & stroke, stock compression ratio, stock cylinder head & valves, stock header pipe.  We have installed a DR650 cam ($230 or $366 with rockers), PWK38 carb ($28), K&N RD-0710 air filter ($40), modified airbox, catch can ($20), and LCGP 2.5” resonator with baffle ($100).

We have improved the overall performance of the motorcycle.  Carburetion is excellent but fuel economy is not as good as we achieved with the stock carburetor.  Backfiring has been eliminated.  Audible noise has increased a modest amount, but the quality of the exhaust note is more pleasing to the ear.  Compared to the box-stock motorcycle, third gear acceleration has improved by 5.24 seconds, and fifth gear passing acceleration has improved by 4.45 seconds (14.68 seconds if you run it all the way up to 5500 rpm).  It’s got some muscle now.

That’s pretty good, but the price tag is starting to creep up.  The DR cam will set you back about $230 bucks, and if you opt for new rocker arms you can add an additional $136 to the tab.  We’ve done some minor work on the engine that required a good understanding of cam timing.  Most of us could accomplish these simple modifications for under $560 bucks.  The tests show that in this state of tune it runs a bit better with the stock header.

Now it’s time to break out some special tools.  Next stop on the Power Train?  Flywheel.  Let’s see what happens when we lob off some of that rotating mass.  Part 6 will install a three-inch flywheel.

At this point, I have done 171 WOT acceleration pulls to dial in the different combinations.  There’s a little over 2400 miles on the engine since it was restored to box-stock configuration.  The old girl is still holdin up good.  No leaks.  No ugly noises.  Not using any oil.  Just a bit of oil accumulating in the catch-can (possibly due to the stratospheric rpm).  It’s still a solid motor.

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