Oil everywhere
Elite HDF Member
Joined: Jul 2008
Posts: 4,741
Likes: 45
From: Indian Land, SC
I can also personally say that copper tubing mod works well. I would still be using it but I cracked my Big Sucker backing plate and I decided to go with the solid billet FM air filter set-up. Still not 100% sure that it will not drip down the backing plate but I have to wait for the summer heat to test its claims.
Road Warrior
Joined: Dec 2006
Posts: 1,716
Likes: 8
From: General Sherman's Christmas Location 1864
My 2007 with K&N
Haven't really put miles on it yet.
Mine just about stopped after "adjusting the oil level"
but still have some every now and then..
I got the idea from other threads in here
So we'll see it it was worth it
Haven't really put miles on it yet.
Mine just about stopped after "adjusting the oil level"
but still have some every now and then..
I got the idea from other threads in here
So we'll see it it was worth it
Stellar HDF Member
Joined: Jan 2008
Posts: 3,036
Likes: 65
From: Earth
I tried the Harley new style breathers in my high compression twin cam and they helped but the problem wasn't solved. Tore the top end back down and installed the Doherty breathers after drilling the rocker asm's and problem was solved. In Harley's defense, their new style breathers were metal and replaced my plastic, looked like the Doherty Myst Free, but said nothing about drilling the oil passgae. Maybe the key is the oil return passage being drilled to facilitate the oil return to the bottom....
Do the heads need to come off to drill these oil return passage holes?
Stellar HDF Member
Joined: Aug 2012
Posts: 2,664
Likes: 184
From: Indiana, USA
No, Just remove the top plates of the rocker boxes, remove 4 screws per rocker ASM and take to your drill press to drill out then reassemble. These holes are in the factory casting in the breather pocket. Seems to me this is clear indication that if the oil mist can be pulled into the breather ASM and if the oil is successfully seperated from the mist, it will not get to the air cleaner ASM....Which is why the bottom of the breather is being drilled to give the seperated oil every chance to stay inside the engine and not be sucked into the air cleaner.
http://dohertymachine.com/
2- tails (optional)
1. Begin by removing the seat and rear mounting bolt securing the fuel tank.
2. Lift fuel tank up from rear approximately 3 inches and prop up. NOTE: On FL models equipped with fuel injection fuel line will need to be disconnected at fuel tank to obtain adequate clearance.
3. Remove the six (6) bolts securing the Rocker Box cover. Discard old gasket.
4. Remove the two (2) bolts securing the stock breather module as shown in Figure 1.
5. Replace stock breather module with the MYSTFREE unit. Install two (2) ź 20 bolts with washers (included) and tighten alternately to 90 in-lbs. Install gasket and Rocker Box cover and bolts in sequence shown in your shop manual. Torque to factory specs.
6. Repeat above instructions for 2nd MYSTFREE unit.
7. Reinstall gas tank mounting hardware and fuel line as required.
http://dohertymachine.com/
INSTALLATION INSTRUCTIONS DOHERTY MACHINE MYSTFREE
™
MYSTFREE UNIT DIRECTLY REPLACES THE FACTORY BREATHER UNITS
INTRODUCTION
: These instructions describe the procedure for properly installing the MYSTFREE breather kit on the 1999 – 2006 TwinCam™ 88.
Review instructions carefully before beginning as they contain important information.
Review instructions carefully before beginning as they contain important information.
CAUTION
: A CAUTION indicates special procedures that must be followed to avoid injury to a motorcycle operator or person inspection or repairing the motorcycle.
COMPONENTS:
2- MYSTFREE Breather Units
4- ź 20 Bolts
4- ź" AN Washers
2- MYSTFREE Copper Base Gaskets
2- MYSTFREE Cover Gaskets
2- Rocker Box Cover Gaskets
1- Shorter bolt for use in Sof 4- ź 20 Bolts
4- ź" AN Washers
2- MYSTFREE Copper Base Gaskets
2- MYSTFREE Cover Gaskets
2- Rocker Box Cover Gaskets
2- tails (optional)
PROCEDURE:
(All Models Except Softail – See Reverse Side for Softail Supplement)
1. Begin by removing the seat and rear mounting bolt securing the fuel tank.
2. Lift fuel tank up from rear approximately 3 inches and prop up. NOTE: On FL models equipped with fuel injection fuel line will need to be disconnected at fuel tank to obtain adequate clearance.
3. Remove the six (6) bolts securing the Rocker Box cover. Discard old gasket.
4. Remove the two (2) bolts securing the stock breather module as shown in Figure 1.
5. Replace stock breather module with the MYSTFREE unit. Install two (2) ź 20 bolts with washers (included) and tighten alternately to 90 in-lbs. Install gasket and Rocker Box cover and bolts in sequence shown in your shop manual. Torque to factory specs.
6. Repeat above instructions for 2nd MYSTFREE unit.
7. Reinstall gas tank mounting hardware and fuel line as required.
CAUTION: IF FUEL LINE WAS REMOVED
INSPECT FOR ANY FUEL LEAKS BEFORE STARTING VEHICLE.
INSPECT FOR ANY FUEL LEAKS BEFORE STARTING VEHICLE.
NOTE:
ON SOFTAIL MODELS (REAR CYLINDER ONLY) INSTALLATION OF THE MYSTFREE WILL REQUIRE THE REMOVAL OF THE TWO BOLTS SECURING THE STOCK BREATHER MODULE AND THE 4 BOLTS SECURING THE ROCKER ARM STAND. REMOVE ROCKER ARM STAND AND MODULE AS A UNIT.
DISCARD STOCK BREATHER MODULE. INSTALL MYSTFREE UNITS MAKING SURE THAT THE ź 20 BOLTS ARE INSERTED IN MYSTFREE UNIT PRIOR TO INSTALLING ROCKER ARM STAND. REINSTALL ROCKER ARM STAND ASSEMBLY AND TIGHTEN BOLTS TO 20 FT. LBS
DISCARD STOCK BREATHER MODULE. INSTALL MYSTFREE UNITS MAKING SURE THAT THE ź 20 BOLTS ARE INSERTED IN MYSTFREE UNIT PRIOR TO INSTALLING ROCKER ARM STAND. REINSTALL ROCKER ARM STAND ASSEMBLY AND TIGHTEN BOLTS TO 20 FT. LBS
SEE NEXT PAGE FOR
IMPORTANT SUPPLEMENTAL INSTRUCTIONS
NOTICE FOR ALL
FL MODEL MOTORCYCLES
NOTICE FOR ALL
FL MODEL MOTORCYCLES
FL Model Motorcycles require a
total oil capacity of 4 quarts. Overfill conditions can result in oil carryover even after the installation of the Mystfree units. When oil and filter is changed in an FL Model the recommended refill capacity is 3.5 quarts NOT 4 quarts since approximately ˝ quart remains in the engines sump and gear case during an oil change.
DRILLING ROCKER ARM STANDS (OPTIONAL ALL MODELS)
Included in your Mystfree kit is a number 43 drill bit, which measures .089 in diameter. There are two oil drain return holes located in the rocker arm stand cavity in which the Mystfree mounts.
See photo
We have found that the oil return holes in the rocker arm stand are too small to adequately return standing oil. If you are experiencing a high volume of oil carryover exiting the breather system; we recommend the following modifications: These two holes presently measure .060 in diameter. In Twincam 88 style engines, that are moving above normal amounts of oil to the rocker box area, it is recommended that these holes be enlarged to .089. This is easily accomplished by removing the rocker arm assemblies and enlarging the holes with a common electric or portable drill with the drill bit that has been provided in your kit.
If you need further technical assistance, please contact Doherty Machine at 928-541-7744. Our office hours are Monday – Friday 8:00 AM – 5:00 PM MST See photo
We have found that the oil return holes in the rocker arm stand are too small to adequately return standing oil. If you are experiencing a high volume of oil carryover exiting the breather system; we recommend the following modifications: These two holes presently measure .060 in diameter. In Twincam 88 style engines, that are moving above normal amounts of oil to the rocker box area, it is recommended that these holes be enlarged to .089. This is easily accomplished by removing the rocker arm assemblies and enlarging the holes with a common electric or portable drill with the drill bit that has been provided in your kit.
Seasoned HDF Member
Joined: Aug 2011
Posts: 11,814
Likes: 5,120
From: SW Ohio
Don't make it any harder than it is brother. Block the vent tube holes on the back of the intake plate and run a hose off each breather bolt down to a T. Then run a hose from the T to the ground under the engine.
The pistons are almost as big as paint cans, there's gonna be some internal pressure because of that. HD routes that oil mist and pressure into the intake stream for EPA purposes. Plain and simple, every big displacement V twin is gonna mist something, especially an air cooled one. Running the oil "a little low" isn't gonna change anything, it's a dry sump engine AND you'll just increase oil temps because with less oil, the remaining oil has to cycle back into the engine sooner.
If you have one of the SE backing plates that covers the breather bolts with the intake itself, Fuel Moto sells one that uses the hoses. It's an easy mod and you'll never deal with it again. This is one of those topics where everyone has a fix and theirs is the best one. I'm no different so take what I'm telling you with that in mind.
The pistons are almost as big as paint cans, there's gonna be some internal pressure because of that. HD routes that oil mist and pressure into the intake stream for EPA purposes. Plain and simple, every big displacement V twin is gonna mist something, especially an air cooled one. Running the oil "a little low" isn't gonna change anything, it's a dry sump engine AND you'll just increase oil temps because with less oil, the remaining oil has to cycle back into the engine sooner.
If you have one of the SE backing plates that covers the breather bolts with the intake itself, Fuel Moto sells one that uses the hoses. It's an easy mod and you'll never deal with it again. This is one of those topics where everyone has a fix and theirs is the best one. I'm no different so take what I'm telling you with that in mind.
Novice
Joined: Nov 2013
Posts: 15
Likes: 1
From: middletown, Ct
My 01 Softail has over 70,000 miles. It was blowing out the breather bolts, and into my D&M AC mounting bracket so bad that it choked my carb because of the excess oil...This happened at 75-85 sustained highway speeds. I put in HDs breather upgrade ( only about $30 ), and I drilled out the drain holes under the breather assembly to .089 for better drainage, and the oil "puking" stopped... A lil tip: grease on the drill bit, a slow speed drill, and you can drill out the holes while the rocker assembly is on the bike. A small chamfer with a 1/4' drill will help also. Deburr and clean well, removing any small chips with grease on a q-tip. Re-assemble top rocker box with new gasket, put on gas tank, and ride...
Last edited by mrbreezehd1; Nov 20, 2013 at 11:59 AM.
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Seasoned HDF Member
Joined: Mar 2007
Posts: 66,948
Likes: 4,573
From: TOAK western branch
My 01 Softail has over 70,000 miles. It was blowing out the breather bolts, and into my D&M AC mounting bracket so bad that it choked my carb because of the excess oil...This happened at 75-85 sustained highway speeds. I put in HDs breather upgrade ( only about $30 ), and I drilled out the drain holes under the breather assembly to .890 for better drainage, and the oil "puking" stopped... A lil tip: grease on the drill bit, a slow speed drill, and you can drill out the holes while the rocker assembly is on the bike. A small chamfer with a 1/4' drill will help also. Deburr and clean well, removing any small chips with grease on a q-tip. Re-assemble top rocker box with new gasket, put on gas tank, and ride...
Novice
Joined: Nov 2013
Posts: 15
Likes: 1
From: middletown, Ct
Yes, a .089 hole/drill bit is right...I have fixed that error, good catch!! Thnx!
Last edited by mrbreezehd1; Nov 20, 2013 at 12:07 PM.