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spit happens
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Discussion Starter #1
Do I need that hooked up to the air cleaner assy.?Basically all it does is get the bad air out of the crankcase.That should give me cleaner intake charge into the cylinders.
Has anyone tried a crankcase evac. system with any success?Meaning have a tube go from the rocker cover to the exhaust.It works on drag cars.
 

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SNAFU
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13,094 Posts
One of the reasons it's routed that way is to evacuate the crankcase utilizing the vacuum created in the airbox. If you run topless that's gone.

As long as the crankcase can vent you're OK. There really isn't any reason to pull a vacuum in the crankcase so if you're concerned about getting cleaner air into the intake you can re-route the crankcase vent into a small K&N universal filter. This trick has been used extensively on Buells.
 

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spit happens
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Discussion Starter #3
As long as the crankcase can vent you're OK. There really isn't any reason to pull a vacuum in the crankcase


From what I've found out from working on cars that you need the vacuum. What it does is that it pulls the rings more towards the cylinder walls.Thus creating less blowby past the rings.meaning a bigger mixture of gas to burn and also getting more exhaut out of the cylinder.
 

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SNAFU
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13,094 Posts
Vinny,

Of course you are correct but the difference in HP is very small for the cost of pulling a vacuum. I know, we used to run a vaccum pump on a Class 1 Offshore motor. The system cost $$$$, pulled about 10 - 15 in/Hg gave is 10 HP (in a 750 HP motor)!!!! :eek

Hardly worth the effort since the best net gain on a street V-Rod would be about 1 hp. Using the intake or exhaust would at best pull 1 to 2 In/Hg so the results would be even less. IMHO....

Just go with the stand alone filter, it's the best / cheapest solution.
 

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spit happens
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Discussion Starter #5
Do you have a part# for the k&n filter?
 
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