Installing the Krankvent from ET-Performance by Pat Martin

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Installing the Krankvent from ET-Performance by Pat Martin

Postby Justin » Sun Feb 08, 2015 6:56 pm

[Editor Note from GRAM: ] I have used the Krankvent for a number of years now, and have been very pleased with it. Subsequent to an offer from the manufacturer for a unit to review, I asked Pat to install it on his bike and provide the basic installation instructions below. It is more expensive than using a PCV valve or an external air filter, but provides some real benefits with regard to endurance and maintaining best head vacuum.

ET-Performance has adapted thier very popular crankcase vent (Krankvent) for use with the Roadstar. A lot of us are currently using PCV Valves or external air filters to provide this functionality when we change out the stock air kits on our bikes. Some are even using open tubing run to the ground. Each of these serves its purpose by allowing the excess pressure to be relieved from the heads and crankcase during a normal combustion cycle. In the stock configuration, this pressure (and its accompaning oil blow by) are vented to the air kit, which sends the air and oil into the carburetor for consumption in the normal air/fuel mix.

The problem is normal for combustion engines, and occurs in the heads above the valves and below the piston rings in the crankcase. When the pistons are moving up and down, they are drawing in and expelling air into this "non-combustion" area. Some of this pressure is caused by the normal movement of the piston in its cylinder, some from "blow by" that escapes around the sealing ring of the piston. This creates a pressure in the crankcase that can sometimes cause seals to leak. It also creates an energy in the form of air pressure that the pistons have to work against. Every combustion engine needs a way to relieve this pressure for best performance.

In the stock Road Star configuration where venting is sent to the carburator, the oil "blow by" products in this vent lead to a general "gumming up" of the carburator from accumulation of the oil blow by . Although not harmful to the carburetor, this leads to dirty carbs that occasionally need a good cleaning to remove the accumulation and optimize thier performance. Occasionally, in particular when engine mixes lean toward being too lean and thus building up excess heat, this can end up being a messy job as the oil blow by tends to get "cooked" into the throat of the carb by excessive heat.

Providing an aftermarket crankcase ventilation method for your bike helps to keep the carburetor cleaner, and in particular with aftermarket air kits, avoids the problems associated with oil leakage (from the open elements of the aftermarket kits) onto the engine below the air kit and oil spray from the same source that tends to spread itself onto our nice shiny chrome parts in the wind behind the air kit.

In the case of the Krankvent, there are a few other benefits that are worthy of consideration:

The Krankvent is designed to let the pressure out of the engine (piston coming down), while limiting the amount of air that is allowed back in (piston going back up). This creates a partial vacumn inside the engine which reduces the force (internal air pressure) that the piston has to push against while returning to its starting position for a combustion cycle.

The folks at ET-Performance claim the Krankvent will last forever because of the material it is built with (we have heard of no failures). They also claim that higher horse power can be obtained, piston rings seal better, and emissions are reduced. The Krankvent is very simple to install, so let's take a look at the kit and installation.

We can see what is included in the kit in this picture. Installation instructions, the Krankvent, plastic ties, and two hose clamps.


You want to make sure that you selected the correct hose to install the Krankvent. We are going to install it in-line with the hose on the rear head, on the right side, and towards the front of the bike. The arrow in the picture points to the correct hose.

After you select where you want to install the kit, cut the hose and install the Krankvent. Insure that the Krankvent is allowing air to escape away from the engine before installing. You can do this by blowing through it to see the allowed direction of air flow. Secure it with the two supplied hose clamps, and tie it up with the two supplied plastic ties. Installation is complete as seen in the picture. Keep in mind that my hose is routed to a small filter on the left side of the bike. Your hose might still be routed to your air cleaner which will require a different location to install. This is a very simple item to install.

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