 Techline-Feb09-H-D 110" CVO -Part II: The valve springs and other issues (cont.)
This article concludes in the next thread.
Controlling Oil Blowby
There is no provision to control oil blowby (carryover) in the CVO 110" except with the new oil pump (#26037-06). This was introduced on the 2006 Dynas and was carried forward, with some changes, to the CVO 110". Oil carryover is exacerbated by sustained high-rpm riding and/or increased swept volume in the cylinders, which is a fancy way of saying increased displacement or more cubic inches. The descending pistons displace an oily mist from the flywheel compartment and into the heads where the oil is supposed to be separated from the pressurized air by the breather apparatus located between each rocker arm set. There is one breather apparatus in each head. The now oil-free air then vents into the air cleaner via a hollow breather bolt in each head, while the separated oil flows, via gravity, down the oil return passage in each head. Sustained high-rpm riding necessitates pistons that move much faster and many more times per minute, thus displacing much more oily mist. Increased swept volume means that the pistons have a greater diameter (bigger bore), or move farther up and down the cylinder bore (longer stroke), or a combination of both, which results in a greater swept volume that displaces more oily mist into the rocker boxes.
The CVO 110 has a standard stroke of 4-3/8", which is also used in the TC 96. This is 0.375" longer than the 4.00" stroke of the TC 88s. However, its massive bore of 4.00" is a full 0.250" larger than the stock TC 88 or TC 96 bores and still 0.125" bigger than the TC 95 and TC 103 big-bore kits. The CVO 110 oil pump (#26277-06), as well as the 2006 Dyna and TC 96 oil pump (#26037-06), removes much more oil from the gearcase and bottom-end compartment than the 1999-2006 oil pump series (#26035-99, #26035-99A, and #26035-99B). This helps control oil blowby because there is not as much oil lying around to combine with the
displaced air to form an oily mist.
Chris is a well-seasoned biker who’d brought in his CVO 110. He rides at a good clip for long distances (sustained high-rpm riding), so I asked him if he experienced any blowby situations. He said that, yes, a fine, oily mist did vent to the outside of the engine, but, being an older rider with numerous oil-related carryover experiences, he did not view his 110 as having a problem worth worrying about. Chris is a tolerant guy as long as his bike does not stop running. I asked Steve to install an S&S Cycle reed valve, which fits between the oil pump and the inner right engine case. The reed valve controls displaced air that travels through the pinion bearing rollers from the bottom-end cavity into the gearcase, where it then continues up the pushrod tubes and into the rocker boxes.
Last year, my 2007 TC 103 became the guinea pig in a 0.110" drain hole experiment. It worked for me, so I asked Steve to do the same for Chris, making the already enlarged drain hole even larger. He enlarged the oil drain hole in the heads to 0.103" from the stock TC 88 size of 0.060" to assist the oil drainage of the heads. Steve also did the previous upgrade recommendation of 0.089" to my bike as part of our test. It’s easy to make this hole bigger but very difficult to make it smaller, if you go too far.
I then decided to put this blowby issue to rest for good. I asked Steve to replace the stock single-chamber oil-separator H-D breather apparatus in each head on Chris’ engine with a Doherty Machine dual-chamber oil-separator Myst Free breather. My hope was that the Doherty Machine setup would separate the oil from the pressurized air more efficiently. We could also have just replaced the rocker boxes with TP Engineering boxes, which also incorporate a different type of dual-chamber oil-separator that is a study in physics.
Other causes of oil blowby are usually mechanical installation errors inside the gearcase. These errors can be a misaligned oil pump, or pinched, wrong sized, or missing O-rings between the components that distribute oil to other engine compartments. Steve does not make these types of mistakes during reassembly.
CVO 110 Injectors
You won’t believe this one! There is a stock TC 96 EFI setup on the CVO 110! I was hoping for bigger fuel injectors on the 110’s EFI throttle body, so I could get a little more fuel into the cylinders to lower the air/fuel ratio below 14.7:1. I was also expecting a larger-sized throttle body. H-D, in the Screamin’ Eagle 2008 catalog, has a 58mm throttle body with matching injectors. Ah, I thought, this is perhaps too big for the CVO 110; I want something smaller. Reading further, I found out this unit is for engines with more than 100 hp at the rear wheel. Realistically, without changing a bunch more stuff, I figured Chris’ bike would have somewhere between 100 and 110 rear-wheel horsepower when done. I still thought this throttle body was too big.
Article concludes in the next thread. See back issue for pix and extra information. | 
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