Installing a Crankcase Breather

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Written by Fatbike   
Friday, 11 June 2004

Reprinted by Permission from FatBike

This is a fairly simple project that requires very little time and effort.  The idea is that when the crankcase breathes under pressure, it can push a little oil into the breather box.  I have found oil in the carb throat and that canít be good for performance.  By re-routing the breather line into itís own filter element, you eliminate the possibility of oil getting into the carburetor.  Many have also commented about the mess that the oil makes on pipes using an aftermarket breather box.
All you need is the breather itself (I found mine at a swap meet for $12.00Ö) and about 3 feet of fuel line.  The fuel line works well because it wonít collapse around corners.  You will also need to cap off the inlet at the back of the breather box.  I found a cap-off end at the local automotive store.

Hereís how itís done:

1. Remove the tank.
2. Remove the hose that runs from the top of the rear cylinder to the back of the breather box.
3. Remove the side covers.
4. Connect the new line to the top of the cylinder head.
5. Run a wide loop from right to left, and toward the rear.
6. Route the hose down between the frame and the oil tank (photo).
7. Measure and cut the line down by the passenger peg.
8. Remove the front bolt that holds the passenger peg and use it to hold the breather in place.
9. Connect the line to the back of the new breather.
10. Cap off the inlet at the back of the breather box.

Tidy everything up and your done.

The breather can be mounted on either side.  I chose the carburetor side because I thought that the breather complimented the Big Air Kit.
 

**Update**   Duh... mount it on the stand side or the mess just pukes out onto the pipes!  Sometimes I think I need my head examined!

Route the hose here...

Route the crankcase breather hose as shown...

Installation...

Mount using the passenger peg hardware...

Front View...

I braided the end of the hose for a cleaner look...

Rear View...

Full View...

Very subtle installation...



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DISCLAIMER: This information and procedure is provided as a courtesy and is for informational purposes only.  Neither the publishers nor the authors accept any responsibility for the accuracy, applicability, or suitability of this procedure.  You assume all risks associated with the use of this information.  NEITHER THE PUBLISHERs NOR THE AUTHORs SHALL IN ANY EVENT BE LIABLE FOR ANY DIRECT, INDIRECT, PUNITIVE, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, OF ANY NATURE ARISING OUT OF OR IN ANY WAY CONNECTED WITH THE USE OR MISUSE OF THIS INFORMATION OR LACK OF INFORMATION.  Any type of modification or service work on your motorcycle should always be performed by a professional mechanic. If performed incorrectly, this procedure may endanger the safety of you and others on your motorcycle and possibly invalidate your manufacturerís warranty.


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  Comments (4)
Written by Solo, on 10-04-2011 07:41
I mounted mine on the left side, so far so good. Almost seemed to run better? But that could just be the psychological effect when tinkering on my ride? 8)
Written by mikeleblanc, on 01-05-2011 09:45
If you mounted it somewhat higher, would that negate the oil escaping? I'm assuming gravity and all that would come into play there.
Written by lowbattery2001, on 08-25-2008 23:08
I just finished this to my bike also. But I mounted mine under the bike just for that reason. Not sure how mine will work or how long it might last But its worth a try...
Written by wildrat, on 11-01-2005 01:15
Gave me another idea on a mounting position for my breather I bought. I will need to make a brackett for the filter.I wonder though about oil misting when running down the road. How much dirt accumulates from the misting oul on the side of the bike, or is blown away to the point of no oil on the bike for the durt to accumulate? 
 
Wildrat

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