Harley-Davidson® 2007

Road King®, Electra Glide®, Road Glide®, Street Glide®, Ultra Classic®

 Dyna Super Glide®,  Dyna Wide Glide®,  Dyna Low Rider, Dyna Street Bob®

Softail Standard®, Softail Deuce®, Softail Fatboy®, Softail Deluxe®, Softail Heritage®


     Monday October 16,2006.  I got this email late last week.  It came in signed by a person whose name was so strange I could not help but run it through several search engines.  This may be the first time I have run a first and last name web search on someone and not gotten at least one hit.  According to the world wide web the author of this is non existent.  It came through a hotmail address and I even used their internal search engine on the address and the name and didn't get zip.  Really strange!!

     I really want to post the name but am going to resist since this person asked me not to.  I have replied to the original email but they have not communicated since the original receipt of this email.  Normally I would not post something that I could not verify a name or at least an active email address but the information seems like it needs to be posted.  Ya'll read it for yourselves and draw whatever conclusions you want.  I cannot verify anything about where this information originated but it seems well thought out so here it is.

     Friday October 20,2006.  Mr. Anon (short for anonymous) has resumed communications.  He has promised that more information is forthcoming.  Apparently this "person" is quite careful about arraigning his/her/their thoughts.  Other than the fact that there is two way communication I still have no verification that this persona actually exists.  Read it for yourself and discern what you may from the information.


Hot running engine:

The problem is with the rider feeling the engine heat or sensing the engine running hot, is a design of the new motors of the present day.  Be it an automobile or a motorcycle, the Federal Environmental Protection Agency (EPA) has enacted new laws after 24 years, that as of 2006, have been revised governing motorcycles.  Be forewarned that the Emissions laws are to be even stricter in 2008.

These new laws are of course more stringent in keeping down vehicle emissions, and as such, the engines must run leaner.   As we all know, the leaner an engine runs (to a point), the hotter it runs.  With a water-cooled engine, this heat is carried away to the radiator.  With our beloved air-cooled engines of the Harley, the cooling fins on the cylinder and head, the exhaust piping, and the oil tank give off this heat.  Harley has added ingenious piston oil cooling by spraying oil on the bottom of the piston to carry away heat.  This heat, now in the oil, goes to the oil tank.  If the tank is under your seat, then you feel it.  With the DYNAs, the oil tank is below the transmission, which is further away and helps the rider.

All of this heat must go somewhere.  Unfortunately, since a motorcycle rider is sitting right above the engine, straddling it (and maybe the oil tank too), this heat is felt.  Under moving conditions, this should not be an issue, HOWEVER, those motorcycles with windshields and especially lower fairings, seem to feel hotter to the rider.  It is understandable that with the windshield, faring, and saddlebags, the airflow over the engine and around the rider is obstructed.  This obstruction which is desirable by some people, is unfortunately causing the heat to be not carried away, but rather pulled up to the rider at speed.  As for the rider at a stoplight feeling the heat, this is not really the issue since they are not moving.  That is the convection current of rising heat, drifting up to the rider.

As for blaming Harley for the heat, and demanding they be responsible for fixing it for free, it goes like this:  Harley-Davidson is a vehicle manufacturer.  If Harley is to sell motorcycles, then they MUST comply with the current emissions laws as of the time of manufacture.  If Harley or any other motorcycle manufacturer did not comply with the laws, they could not sell the vehicle.  Period.  This applies to ALL manufacturers of ALL vehicles sold for road (highway) use.  The new vehicle MUST pass a stringent emissions and noise laws to be sold ...  sold off the showroom floor.

Therefore, the Harley factory, and the Harley dealerships, CAN NOT do anything to remedy this problem, without violating the emissions laws.  The fix is to simply richen up the fuel mixture, but this would make the motorcycle fail the emissions test for a new vehicle.   So as you can see Harley has its hands tied.

There are apparently various (approved?) options AFTER the sale.  Including a "Heat management" EFI download.  But this is between you, Harley-Davidson, and your Harley dealership to investigate.

The 5th gear noise:

The new 6-speed transmission has the 1st and 5th gears as the original and stronger "spur" gear or "straight-cut" gear and 2nd, 3rd, 4th, and 6th are helical or "herringbone" cut gears.  Harley always used spur gears until this new 6 speed transmission.  This transmission came out in the DYNA 2006 models since last year mid 2005.

Please understand that the angle cut helical gear is much quieter than the spur (straight) cut gear!  Want proof?   Have you ever noticed that when you back-up your car or truck, the vehicle makes a whining noise that is does not make in the forward gears?   Depending on how low your reverse gear is, this is usually quite noticeable with vehicles with a low 1st gear.  You hear the "whine" because Reverse is usually spur cut gears.

It appears Harley has made the around town and highway cruising gears helical to be quiet.  The 1st gear being a starting gear with a load on it (especially those that do "drag starts") and 5th may be considered a passing gear.  So they were left straight cut for more strength.  To see a colored representation of the transmission and get some information look at the site:  

Remember as above in the Heat issue, having a windshield, faring, and saddlebags, the airflow over the engine and around the rider is obstructed.  This allows the rider to hear more noise coming from below them.  Part of this could actually be reflected off the windshield, faring, and saddlebags back up to the rider.

It's odd that the DYNA Super Glide has had this transmission for the last year, and people riding the DYNA are not complaining seemingly at all (or a very, very small amount of people) concerning transmission noise and for that matter heat.  It is believed that the lack of; windshield, faring, and saddlebags are why they "seem" quieter.  The noise of rushing air over the helmet drowns it out.  As for the above mentioned heat matter, that same unobstructed rushing air over the engine is carrying away the heat and those complaints are few too.

As previously stated, it seems the Super Glide and Street Glide does NOT seem to have hardly any complaints on the heat (or 5th gear) issues.  However, the Ultra Classic Electra Glide seems to have a 95+% complaint factor on this.  It may well be the lower fairings and larger windshield are simply blocking too much airflow.

Harley-Davidson® FLHX/FLHXI Street Glide

2007 Harley-Davidson® FLHTCU Ultra Classic® Electra Glide®

Lastly, don't forget you have a warranty.  If you opt for the longer warranty, then you are covered for even longer if something fails.

Hopefully this will answer some questions and make people feel better.  If not, well I tried.




     There was a good deal more to this email above and below the "begin public" and "end public" tag lines.  I am going to keep it that way even though I really want to let it all hang out.  This "person" is really informed and writes very well.  I hope that they communicate some more on the subject.  I have promised to all of ya'll that I will keep anything you communicate to me private if asked and I am going to stick to it no matter how tempted I am.

    (1/25/2007)  I received this a while back but due to time restraints I am just now getting it posted.  I apologize to its writer and the viewing public...  Mr. Anonymous has come down from on high again to grace us with more intimate knowledge of the inner workings of a late model Harley-Davidson engine.  Ya'll need to read this and appreciate that this person exists and chooses to share his knowledge.   I hope you get full value for your money on this one. 

Engine cooling and the Twin Cam 88/96

The TC (Twin Cam) 88 and now TC96 have 50% to 60% more finning on the head and cylinderscompared to yesteryears Harley motors.  In the past, the old shovelheads had way less finning,and one did wonder about their cooling abilities.  It appeared that with the design of the hemi-head, and corresponding dome on top of the piston, would interfere with flame front propagation, especially if the spark plug was not *perfectly* top-dead-center in the head.  With an off-center, or side placement of the sparkplug, the top of the piston's dome would partly block the flame.  To further make matters worse, the hemi-head did not seem to have any "Squish bands" or "ledges" in the combustion chamber's head.  "These "squish bands" aided in air/fuel mixing in the cylinder."
  The lack of "squish bands" leads to rich and lean sections in the air/fuel charge called "stratification".  In some cases this "stratification" (with lean areas) caused a "lean miss" if this lean area happened to be around the spark plug at the time of firing.  In other cases it would encourage a detonation problem.  Compared to today's engines, if the fuel mixture was anywhere near the common lean [stoichiometrically correct 14.7 to 1] air/fuel mixture ratios of today, it would sputter, detonate and run bad.  Therefore, the shovelhead with its hemi-head, ran rich on purpose to overcome these overly lean spots to prevent miss-fires and detonation.  Ultimately, this richness also meant less heat for the rider to feel, so I guess it all "panned" out.  (Notice the pun!!)

Harley-Davidson's current combustion chamber design is modern.  If you note, the TC88 & TC96 actually has slightly higher compression ratio as compared to the older Shovelheads and Evolution engines.  The 2007, 1200 Sportster, has a Compression Ratio of 9.7 to one and the Big Twin is 9.2 to one.  The old shovelhead was 8 to one, with a hemi-head.  The newer designs allow higher compression ratios due to improved fuel mixing in the cylinder.  The improved mixing is accomplished by having a "squish band" (mentioned above) around the outer edge of the head, causing the air/fuel mixture to be squished by the rising piston, and forced into the center of the head which shaped like a "bathtub".  This action would force the mixture to quickly move inward and create turbulence, thereby mixing the air/fuel charge more thoroughly.  This modern cylinder head design, even with the higher compression ratio, allows a leaner [and hotter] fuel mixture for increased mileage and to meet current emissions laws.


Detonation & Boundary layers


"fin area has increased 50%"

"60% increase in finning"


Extra reading:
Mixture Quality and Turbulence


The Ignition/Combustion Process

Turbo Systems 102 (Advanced)

     Here is another informative response from our mysterious guru of the late model H-D.  It directly addresses one of the letters posted on this site.  This should really help at least one of our readers understand the issues with his bike and take corrective measures.

Cold or Cool Engine Stumbling / Backfiring (spitting) Through the Intake System

There are two types of backfiring.

1) from the exhaust system; caused by unburned gasses that gather to a great enough concentration then are ignited.
2) in the intake manifold/carburetor; caused by a too lean air/fuel mixture for the running condition or incorrect ignition timing.

The below concerns a Harley rider that has a "cough" after a short warm-up, and the approximate same spot of his trip, "everyday" as he puts it.

  "The only issue I have had with the bike is a slight hesitation shortly after I take off, it happens in about the same place everyday, I roll on the throttle on an on ramp and the bike coughs once and then rolls on." 

The writer mentioned,  "The service guy says there are 2 different warm up modes (he called it hot and cold idle) and said that I was in all likelihood hitting it just as it shifted modes. "

First, the engine needs to be checked that it's tuned within specs.  Is the timing set correctly?  Are the spark plugs OK?  Is fuel delivery OK??  Any Fuel Injector Upgrade Bulletins (i.e. 25 degree injectors)??  etc.

If the engine is indeed in proper specs (this should have been checked by the shop), and all is correct, there still must be a problem somewhere.  The engine simply should not be coughing or spitting.  This problem is most likely a too lean an "Accel Enrichment" setting.  Under some conditions, if
the fuel mixture is too lean, the fuel is still burning after the exhaust valve has closed and when the intake valve opens.  This still burning mixture can ignite the incoming mixture and travel back up the intake manifold to the air cleaner causing the "pop" or "cough" noise at the air cleaner inlet.

This problem should easily be corrected with the proper use of the Screamin' Eagle Race Tuner (SERT) or corresponding Dealer Service tool by simply richening the "Accel Enrichment" setting slightly for the approximate temperature that this misfire happens.

One must try to ascertain the temperature at which the backfire occurs.  Borrow or rent, an Infrared Laser Temperature gauge.  Another alternative would be to get a Food Thermometer (the one with the long metal rod).  With the Food Thermometer, try to stick it into the fins nearest the "Temperature Sending Unit" in such a way as it will not fall off.

Simply ride the motorcycle until the backfire occurs and then safely pull over, off the road, and take a temperature reading (again near the "Temperature Sending Unit").

If the rider is accelerating ("roll-on" as this rider was) a slightly richer mixture is needed because the engine is working harder.  If the temperature reading is around 160F when the backfire happens, then if one were to look at the SERT's ACCEL Enrichment chart, they could see that by slightly enriching the 64 and 80 (centigrade) settings, this lean miss or lean backfire could be remedied. Reference: 
http://www.v-twinforum.com/forums/showthread.php?t=60576  (9th photo)

For another example, if the rider were holding a steady state cruising speed and the temperature reading were around 160F when the backfire happens, then if one were to look at the SERT's WARMUP Enrichment chart, they could see that by slightly enriching the 64 and 80 (centigrade) settings, this lean miss or lean backfire could be remedied.  Reference: 
http://www.vtwinforum.com/forums/showthread.php?t=60576  (5th, 6th & 7th photos)

The goal here is to NOT have an engine that misses and sputters.  This in itself is; annoying to the rider, improper engine operation, and even increases emissions.  Therefore, slight adjustments to the fuel mixture are sometimes needed to compensate for manufacturing variances and quality of fuel.


     If this information doesn't help you understand your new Twincam engine a little better then go back to whatever you were doing (maybe it was watching Survivor or American Idol) and just give up on actually understanding engine design.  I personally look forward to every piece of information this person sends in.    If you have something to add my email is still biners@crowderinc.com.  As soon as, or if, Mr. Anon sends in another nugget I'll post it up.

Page 1 (Houston, We have a problem!)      Page 2 (Our story continues)  

 Page 3 (I hear from others with the same problem)

Page 4 (Our exact fix)         Page 5 (Other potential fixes)

Page 6 (What's up with the noisy gear box??)

Page 7 (Potential buyers are starting to freeze up)

Page 8 (Some folks are quite happy with their '07 H-D's)

Page 9 (Other problems I am hearing about)   Page 10 (other resources)


page 12 (an attempt to gather my thoughts)




The credentials or existence of the authors of testimonial emails has not been positively verified.  I do try to establish at least two way communication with the authors of these posts.  That makes much of this information hearsay at best.  Please use your own judgment when reading these posts.  None of these would stand the scrutiny of a court of law without further verification.