'34 VL Oil Pump Adjustment

[Cossack_38]

Working on a '34 VL with a fresh rebuild, with modern piston rings. The bike is over oiling by a lot right now. I replenish with 2.5 pumps after draining. I measured, and my hand pump, with new tight leather seals, delivers 1.8 fluid ounces per pump. That means that 2.5 pumps should add 4.5 oz to the crankcase. I then ride the bike for maybe 5 - 10 minutes at 25 mph or less, and then I drain out between 10 and 12 ounces.

After draining the crankcase the last time, I left it empty overnight, and then tried draining it again the next day, to see if any additional oil came out. My thinking was that a bad check ball in the hand pump or excessive wear in the mechanical pump might be adding extra oil while sitting ("wet sumping"), but my test implies that this isn't happening. My conclusion is just that the mechanical pump is delivering way too much oil.

The throttle/oiler linkage is now back to stock and properly sequenced, and the high speed oil adjustment is a little less than the factory mark. Referring to the 1934 VL Rider's Manual, I see that low and intermediate speed oiling is adjusted by adding/removing shims from "Screw #2", on the left end of the pump. Here's the question: My pump currently has three washers on the screw: The brass washer (0.017" thick), one "thick" washer (.063"), and a second thick washer (.060"). The Rider's Manual says not to remove the "thick washers", or you risk starving the engine of oil. I am planning to remove a single thick washer, and replace it with an equivalent set of thin washers that I can then remove individually to work my way down from where I am right now. Does that seem reasonable? Am I missing anything else obvious? By the way, does anyone sell the ultra thin (.002") shim washers? I can make some if I have to.

Thanks in advance for the help...

[Cossack_38]

34 Pump adjustments.jpg

[Cossack_38]

Kind of answering my own question, but maybe this will help others, so here goes. I found additional info in Shop Dope #107, "THE 1934 OIL PUMP". After reading this, my oil pump had two thick (1/16") washers, and should have had only one. The sum of the shims it had was 0.140"; Using the info in the shop dope, the typical sum of the shim washers from the factory should be .071" to .079 for a non-sidecar early '34. Later models (like the one I am working on) would be .085" to .093" from the factory.

I set this '34 up with .093" (One 1/16" washer, one .015" brass washer, and eight .002" shim washers. I added 2 hand pumps (3.6 ounces) after draining, then rode through the neighborhood for 12 minutes. I drained 6.5 ounces. Still too much, but headed in the right direction. I'll start pulling .002" shim washers one at a time now...

Shop Dope 107 washers.png

[Steve Slocombe]

Over oiling on '34s is pretty common, especially with a fresh engine with oil rings fitted. The problem is often the left hand check valve passing, but you say this is OK. Don't forget there were long and short versions of that low speed oiler needle in '34 if things don't improve. The pumps will overoil at the factory settings with modern pistons. As well as these low speed shims you have the more/less higher speed settings, and a factory mark on the oil pump body to show where to start. You will need to trim this down as well, maybe 1/16" inch at a time, checking crankcase oil each time you get back from a ride. Make sure the check ball with the weak spring and brass plug in the pump body is seating, as corrosion of that alloy material over time does not help. Keep doing what you're doing and you should be OK. Once set up the pump settings last a long time.