This is a copy of Doherty Supplemental Instructions for the Myst Free valves.
Note drilling out holes part.
IMPORTANT SUPPLEMENTAL INSTRUCTIONS
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 ½ 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 (Sorry, photo would not attach)
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.