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Thread: JD oil system

  1. #1
    Join Date
    Sep 2016

    Default JD oil system

    Whatís the proper procedure for drawing the cases and using the hand pump? Carburetor was dripping over and I went to drain the crankcase and refill. Iím new to this design. Iím used to recirculating systems

  2. #2
    Join Date
    Aug 2013
    1 mile east of the Rocky Mountains.


    Quote Originally Posted by Bmarinac View Post
    What’s the proper procedure for drawing the cases and using the hand pump? Carburetor was dripping over and I went to drain the crankcase and refill. I’m new to this design. I’m used to recirculating systems
    Do you know how your upper end is set up? Oiling "procedure" will depend on what type of pistons and rings are fitted or not fitted. And if your cases have baffles or not. Differnt guys use differnt setups for different road work. What year is your JD? the following discussion is for the mechanical oilers fitted to later 1922 through 1927 models. 28-29 mechanical oilers are similar, but are "automatic" throttle controlled, so the adjustment procedure is different. Early model (before late1922) mechanical oiler adjustment, i know nothing about.

    Original standard setup was constant loss with tapered bore, cast iron pistons, oil control ring, and greater piston/cyl.wall clearances, so the mechanical oiler needed to be adjusted so the right amount of oil was passing through the oiler, into the crankcase, up past the rings and out the exhaust. Too much oil, and cases overfill, overheating. Too little oil, lower end oil starvation and... If you have original setup, then you need to read the Rider's Handbook for the Handbook's straight forward explanation of how the constant loss oiling system works and is adjusted. With the original setup, the hand pump was used for continuous speeds above 45 mph, hilly roads, sidecar use and/or lots of in town driving.

    A number of guys (myself included) are running "dry" engines. That is, in my case, modern Venolia domed pistons with an oil expander ring which does not allow much oil to leave the crankcase, and very little oil up past the rings and out the exhaust. (and i have crankcase baffles front and rear.) So, i have my oiler output set almost as low as possible. i have my oiler set so it will not overfill cases for up to 150 miles. Then i drain the oil and start over again. When the crankcase is empty, i give two full strokes of oil with hand pump. It is a wise thing to check how much oil 1 stroke of your hand pump puts out, that way you know how much oil you are pushing into the crankcase with each stroke of the hand pump, each hand pump may put out different amounts. My hand pump puts out 40 cc or 1.3 ounces per full stroke, when my crankcase is empty, i give the the hand pump two full strokes. Crankcase maximum capacity is about 8-9 ounces, or 240 cc -270 cc. i do not use my hand pump under operation. i am lucky if i put 250 miles per riding season on my engine. Bear in mind, this paragraph is about "dry" engine setup. i add Amsoil Interceptor 2-cycle oil in my gas for valve guide/stem and piston/ring lubrication; 2 ounces Amsoil/gallon of gasoline. (if John Feraci (harleytoprock) sees this post, he can be helpful, he is running the same setup on his '27 and has several hundred miles on his engine.) for oil, i am using Phillips 66 Aviation oil, 50 weight, ashless dispersant.

    Other guys are running flat top (i believe UL) pistons; some guys run different variations of oil rings or even no oil ring at all, others run no baffles in cases or only baffles in rear cylinder. Each variation is generally based on the experience of the owner.

    No matter what your setup, you want to make sure your mechanical oiler is putting out enough oil to lubricate the lower end and not so much it is quickly over filling cases. In my set up, after draining the crankcase, i give 2 strokes of hand pump, ride a specified number of miles, then come back to shop, drain/measure oil that comes out of crankcase, then i compare the amount of oil i started with to the amount of oil that accumulated in the (drained) crankcase during my ride. During this period of adjusting oiler output, i always ride the same amount of miles, that way i can compare oiler output with each adjustment after each ride. The mechanical oiler output is adjusted by adding or removing washers under the screw at the back of the pump. Factory setup is 3 thin (.010") washers and 1 thick (.065") washer. On my setup, i am down to 1 thin washer, and will probably remove that washer, time and another ride will determine my decision to keep or remove the last washer.

    the last thing you need to know is if your hand pump spring loaded ball valve is allowing oil to leak past and fill the cases when the bike sets for any amount of time. if you suspicion your ball valve is not holding oil, drain the crankcases after your ride, let the bike set two weeks without being ridden, then remove the drain plug and see if any oil comes out. if you ball valve is allowing oil to go by, then the ball valve seating must be addressed.

    hope this is helpful. A Rider's Handbook is a very good reference to have.

    per my usual disclaimer, if anyone notes where i have misinformed, please correct me.
    Last edited by Steve Swan; 06-01-2018 at 12:56 AM.

  3. #3
    Join Date
    Jan 2003


    Great description and advice Steve, most of which also applies to the VLs, which I think originally had 3 compression rings on the pistons and no oil rings. I never use the hand oil pump except for putting fresh oil in the cases after draining. You can also check the hand oil pump check valve simply by removing the hand oil pipe and seeing if the valve drips slowly overnight. The VL oil consumption is given as about 800 miles per US gallon, or about 5 ml/mile, so you can kickstart until you are blue in the face and see no oil pumped. If you worry about the mechanical oil pump, remove the oil feed line, plug at the tank, fill the inlet nipple from an oil can, start motor, then watch oil level in the inlet nipple go down and fill from the oil can.

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