I finished installation of the DR650 cam.  I want give you my evaluation of the performance of the cam in this application, and also share some observations.

Installation is straight forward, I did not come across any hidden mine fields.  However, as previously mentioned, the DR cam does not incorporate oiling holes in the lobes like the LS cam does.  I procured solid carbide bits and center drills with the intent of drilling the holes in the hardened cam lobes.  But those bits are mighty tiny.  I kept having this nightmare about snapping one of those little suckers off in the nice new cam lobe.  

After inquiring with another member who I knew was running the DR cam, I decided to chance it.  I now regret that decision.  Not because the cam bit the dust, but because I will be uncomfortable with the oiling issue for a good long time.  I tried visual inspection through the valve covers, and with the engine in the frame you really can't see much.  The only way that I can see to monitor condition is by checking valve clearance periodically.  That's humbug.  My concerns were valid.  I believe the oil holes provide lubrication for the main bearings.  I should have drilled the holes.  Factory tech manual confirms main bearings get oil from top end drains. DBM  7/13/23

I examined the DR setup by reviewing the illustrated parts breakdown.  The DR incorporates a part called the "Head Chamber Plate".  It sort of looks like it serves as the oil reservoir that is part of the LS casting, but it could possibly be some sort of cover intended to keep oil from splashing out of the reservoir.  Anyone familiar with the DR?  What function does the Head Chamber Plate serve (Fig 1, part 21)?  I'm thinking that at sustained high speed the cam lobes will be flinging oil out of that reservoir like crazy, and the supply to fill it only comes from the right side of the cam.  Maybe I'm worried about a non-problem, but I like being sure about stuff whenever possible.  If I drilled the holes I would be sure.  I didn't drill them and now I'm not sure.  If I had snapped off a bit all I would be out is a $165 cam and some time.

Let's get to the nitty gritty.  The results:

1. Cranking compression did not change one bit.  It was 155 psi before I took it apart, and it was 155 psi after I put it back together.  BTW, I adjusted valve lash to .004" all around.

2. Startup was normal.  It fired right up with no enricher.  Starter had no trouble turning the engine over.

3.  Idle was too low on initial startup.  I simply turned in the idle speed screw and it settled right in to a nice, smooth idle.  I didn't even touch the idle mixture screw.

4.  The exhaust note was audibly different.  Ever so slightly louder and at a lower frequency. That's seat-o-da-pants.

5.  Intake noise increased a bit.  Very evident when you blip the throttle.  My modified airbox was making a bit more noise but still well within DBM acceptance limits.  I don't want noise and every little bit adds up.  I think this will be OK.

6.  Vacuum decreased a bit.  I haven't had a chance to do a complete road test on vacuum, but I was able to check it at idle and when I blipped the throttle.  Idle vacuum dropped from 6.5" Hg to 5.5" Hg.  Throttle blip vacuum was about 3 to 8" Hg, now it's 3 to 7" Hg.

7.  Test ride revealed the following seat-o-da-pants performance.  When I initially took off from my driveway I immediately noted soft low end performance.  Like it was very evident.  The all stock motor has the performance curve of a piece of farm equipment.  A dead flat major low end torque that signs-off as soon as things start getting interesting.  This cam did not provide that exhilarating down low pull, but also didn't sign-off early.  Don't get me wrong, it still has ample low end pull, just not as much as the stocker.  Get her rolling and it now actually has a point where it hits the sweet spot.  The exhilaration is now a little farther up the rpm food chain.  On surface streets it felt good, on the freeway it felt better.  Roll it on at 50 mph and it starts to accelerate much like the stocker, but once it hits 55 mph you can feel it hit the sweet spot.  Nice, smooth steady acceleration up to 80 mph.  It's clearly better on the freeway.  

7.1  At no point was there any sign of detonation, pinging, or overheating.  The test ride included surface streets, freeway, and winding country roads (approx. 30 miles total).  The engine was well mannered under all conditions.  Carburation was excellent, clean and steady, no hesitation, no flat spots, no blubber, no erratic idle, zero afterfire.  After a coffee break at Mickey D's, it fired right up (none of that hot-motor starter-stall stuff, but then the compression is still 8.5).

7.2  This performance was recorded with a basically stock motorcycle.  The only mods were airbox & carb jetting (covered in my prior posts).  The exhaust system was untouched, and with the exception of the cam, the engine was bone stock.

7.3  I felt that this post should also include some information on how the cam would run if it was uncorked on both ends, not just the intake.  So I held off on the post until I could run the cam with an exhaust system that flowed a little better than stock.  I modified the stock exhaust system to reduce some of the backpressure (details & pics to follow in a separate post).  I was able to reduce muffler backpressure by 6" H2O.  Note that I did this without increasing the volume any appreciable amount.  It still pretty much sounds like the stock muffler.  Just seat-o-da-pants but it feels quite good.  Very nice out on the freeway.  I hit it on an uphill grade and it pulled smooth & hard right up to 80 mph.  Totally sweet to pass at freeway speeds.  Carburetion still spot-on.  This setup works good.

I hope this thread proves useful to any of you considering the DR cam.  I intend to add a bit more fuel (147.5 to 150.0 and more if she will take it).  Will let you know how it works.  Also plan to do a dyno pull once I completely finish the exhaust (currently DBM stage I, but have some ideas for a stage II & possibly stage III).  I will monitor the valve clearance as much as practicable and update this thread when I have more info.  If any of you are currently running the DR cam, please share your experience.  Let us know how your setup works and how the cam and rockers are holding up.  If you have any sort of trick to monitor cam & rockers visually it would be quite helpful.

I can't comment on the DR650 oil system - but I do have a photo of what the little well looks like after running a Savage engine.  This engine was run while the bike was strapped upright on my work bench, then shut down and the head cap was removed.  The oil in the well under the cam is completely full.  I am not sure that is stays this full while the engines is running - but it is obvious that as the engine is shut down and the oil drains from the bearings and hollow cam the little well is filled up.

DragBikeMike wrote on 05/15/18 at 11:12:47:


You mean they shouldn't do this?

You can't be serious Dave.  That looks like someone took great care in the  application of the sealing compound.  Why you can barely see the squeeze-out.  If the mechanic (I use the term lightly) had used the black stuff you alerted me to, it would almost be invisible.  

Gosh that's ugly.

If you have trouble imagining it, it looks just like this. PO did exactly that to this engine. The head looked like this:

Crap......Now I am going to have nightmares!

DragBikeMike wrote on 05/15/18 at 11:12:47:


That's exactly like I have thought it before, thanks for the clarification. Makes perfect sense.