Triumphrat

enuf · 11-17-2012, 01:40 PM

Recently at the Vintage Bike Show at SLO, there was a display of vintage flat trackers, very nice I might add!
One had vented the oil vent at the top of the frame into the front tappet cover on the same side.
My question is will this do any harm? This would shorten up and clean up some of the hose connections going out below.

Mr.Pete · 11-17-2012, 02:50 PM

It seems to work well enough.Triumph did it on later OIF frames,connecting the oil tank breather to a fitting at the top of the exhaust rockerbox.

The crankcase fumes from the oil tank then need to escape down the exhaust pushrod tube,through the tappet-block holes and into the crankcase,to finally escape out the crankcase breather.Eventually it goes into the same breather hose as the earlier system,running to the rear mudguard.

It looks tidier,but I don't think it works quite as well.
*Crankcase fumes returned to the oil tank are again returned to the crankcase,before they exit the breather.
*Those fumes from the oil tank (about 1/2-pint/minute at 4000 rpm),have to blow through the tappet block holes to reach the crankcase.Oil is trying to drain through those holes,and that oil lubricates the cam lobes and tappets (they will get some other oil splashed off the crank).There isn't actually a lot of oil draining from the rockerbox,about 2 teaspoons per minute or less.

None of this may matter,and it may work equally well.I don't know of any complaints or problems.

dl.allen · 11-17-2012, 04:37 PM

I often wondered how much fumes the oil tank puts off. Im glad I took the time to replumb my 72 back to stock configuration at the "T" connection etc.
1/2 pint per minute is substantial.

triumpt120rv · 11-17-2012, 06:07 PM

I use RetroRod's PCV valve breather set-up. My oil tank vent consists of a short piece of tube with a fuel filter tucked under the tank. Running for 2 summers and right through last winter. Nice and neat. No problemo.