Antidrain Valve
Part Number 641-21/B
>>>> DISCONTINUED. USE ALLOY 641-21 <<<<
Is your Norton or BSA single or twin dumping
all its oil from the tank into the crankcase when you leave it parked? Make sure
you are running thick enough oil (50 wt Summer, 40 wt Fall and early Spring) and
are parking it on compression (pistons at top of stroke to block off any conrod
oilholes).
If the problem persists, you can replace your gear type oilpump with an
expensive new one, or install one of our Antidrain valves into the feed line from the tank to the
oilpump, and get rid of the "oh, no, where did
my oil disappear to?" blues.
This US made version of our popular alloy 641-21 antidrain valve is manufactured
out of virtually unbreakable Lexan, and features a sight window so you can see
your oilflow. In stock now for immediate delivery!
Instructions (pdf)
