Evolution Vent and Vent Plus Kits

Designed to work on all late 1992 and up Big Twin Evolutionâ Harley-Davidson Motorcyclesâ and all Sportsters with the “Nose Breather” (Engine vents at the heads) system. These kits reduce or eliminate the collection of oil at the bottom of the air cleaner assembly.  The design allows the engine to breathe just as it does now, with out the mess.  The Vent Plus kit also acts a Positive Crankcase Ventilation (PCV) valve, reducing internal engine pressures and increasing power by reducing parasitic power loss.

The key is the vent extension.  This extension eliminates the oil from flowing out the vent and on your engine.  The extension does not increase backpressure and does not alter engine operation.  The Vent Plus kit reduces internal pressure of the engine.

 INSTALLATION:

1.     Position the bike on a safe work stand and raise to work height. (optional)

2.     Disconnect the battery, following your service manual.  (Highly Recommended)

3.     Raise or remove your fuel tank(s) to allow full access the rocker boxes. (Refer to your service manual for instructions).

4.     After gaining access to the rocker boxes, remove the front rocker box outer (top plate) assembly following your service manual.

5.     After removing the outer (top plate) rocker box cover, remove the rocker box spacer, following your service manual.

6.     Using the 1/8” drill bit from the kit, and illustration 1 as a guide, drill the tapered drain hole in the spacer as illustrated.

7.     Using the 13/32drill bit from the kit and illustration 1 as a guide, drill the vent hole as illustrated.

8.     If you have a big twin, place the included collars on each vent extension.  If you are installing these on a Sportster, you do not use the collars.  If you wish to use the collars in order to maximize the vent height on a Sportster, you will have to relieve the inside of the top rocker box to get a proper fit and gasket seal.

9.     Place the rocker spacer on a flat surface.  Insert the vent extension into the vent hole as illustrated.   You may need to gently tap the extension into the vent hole. You may also use a press but be careful not to damage the gasket surfaces or warp the rocker spacer. 

10. Clean the spacer and outer cover gasket surfaces.  Ensure that all drilling debris is removed from the spacer.

11. Install new “umbrella” valves in each spacer.

12. Using the correct gaskets, reinstall the rocker box spacer on the front cylinder.

13. After placing the extension in the spacer, reassemble the rocker box using your service manual for reference.

14. Repeat the process on the rear cylinder.

15. After finishing the rear cylinder, reinstall your fuel tank(s) and connect the battery.

The kit includes: Two vent extensions plus two collars for vent extensions,

13/32” drill bit, 1/8” drill bit, Instructions

 Illustration 1.

Notice: This product was formerly distributed by CCP by Direct Parts (www.directparts.com) all rights transferred to www.johnsmotorcycleparts.com I am not affiliated with Direct Parts or Dakota Kid.

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