free website stats program Crankcase Venting | Harley Davidson Forums

Crankcase Venting

90FXRS

90FXRS

Junior Member
Contributor
A friend has asked me, why I don't know, about crankcase vents. I have mine nicely routed up to the S&S backing plate in a braided line that is clipped to the rear jug. He currently has a short piece of tubing with a K&N filter attached to it....dangling under the bike. He's looking at the Hayden Crankcase Pressure Reilief Valve and the Spyke "Stealth" Krankvent.

The underside of his scooter is a little oily. Appears to be coming from the filter. Has anyone had any experience with either or both of these systems? Should they be routed to the backing plate or simply installed with a filter and tie-wrapped to the frame? :small3d012:

Thanks in advance
 
I found that you can use copper tubing bent into an "L" shape that inserts into the bottom breathers vent line inside of the air box (evo's) that will vent right over the inlet of the carb with the end of the tube cut at a 45* shape to expose a bigger profile to the inlet of the carb. Not only does it work well but it also makes the crank case pressure on the negative side from the vacuum that is created. You can hear a difference in the sound of the engine because the pistons can move freer because it is a negative pressure as opposed to atmospheric pressure in the crank.
 
I seemed to have left out one important item....he's riding an 89 FXR.

Glider, I'm not really following you on the description of the the tube routing. I'll read it again and see if I can get it.
 
90FXRS said:
A friend has asked me, why I don't know, about crankcase vents. I have mine nicely routed up to the S&S backing plate in a braided line that is clipped to the rear jug. He currently has a short piece of tubing with a K&N filter attached to it....dangling under the bike. He's looking at the Hayden Crankcase Pressure Reilief Valve and the Spyke "Stealth" Krankvent.

The underside of his scooter is a little oily. Appears to be coming from the filter. Has anyone had any experience with either or both of these systems? Should they be routed to the backing plate or simply installed with a filter and tie-wrapped to the frame? :small3d012:

Thanks in advance
Click to expand...

I was the first on my block to buy and install the Krankvent. I can't say it did anything. I got no power increase as they claimed (seat of pant, not dyno). My buddy and I experimented with it, and he bougnt and installed a PCV valve at autoparts. His seemed to work just like my Krankvent, you could blow but not suck through one end. His cost $4, I think mine cost over $100.
There is no oil coming from the open end of my Krankvent & it looks ok. Previous to the Krankvent I had a small filter on the end of the breather hose, and it needed cleaning occasionally. I've never done anything to the KV.
 
Are you talking about running a piece of tubing from the vent on the bottom backside of the motor to the backing plate?
 
Breeze3at said:
I was the first on my block to buy and install the Krankvent. I can't say it did anything. I got no power increase as they claimed. My buddy and I experimented with it, and he bougnt and installed a PCV valve at autoparts. His seemed to work just like my Krankvent, you could blow but not suck through one end. His cost $4, I think mine cost over $100.
There is no oil coming from the open end of my Krankvent & it looks ok. Previous to the Krankvent I had a small filter on the end of the breather hose, and it needed cleaning occasionally. I've never done anything to the KV.
Click to expand...

How long have you had it installed? I read where it's been tried but eventually failed. Maybe they were trying it on strokers or bigger displacement motors.
 
90FXRS said:
How long have you had it installed? I read where it's been tried but eventually failed. Maybe they were trying it on strokers or bigger displacement motors.
Click to expand...

Since they 1st hit the market, around '94-'94. Probably more than 50k miles.
I'm not complaining about it's operation, but my buddy got the same results with a cheap pcv valve.
 
90FXRS said:
Are you talking about running a piece of tubing from the vent on the bottom backside of the motor to the backing plate?
Click to expand...

I used the stock hard line that comes from the breather on the crank case and goes into the grommet on the backing plate. What I did is to shorten that tube a bit and put the "L" shaped tube I made through the grommet and connect the two with a short piece of hose. Clamps optional.

You can also remove the grommet and use the connector hose in the hole instead with a clamp on both sides of the plate just to hold it secure.
 
Glider, that's where I got lost and probably wasn't clear on my end. He's running a Super E and bought the bike the way it is. Both holes in the backing plate are plugged and the little K&N filter is tie-wrapped under the frame.

Breeze3at, I meant to say I read that the pvc setup didn't last too long.

I guess from talking to him he's not wanting to run a line up to the carb. Don't know why.
 
You must log in or register to reply here.
Back
Top