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Fabricating an impossible to find oil tank for a motorcycle

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  • I very much enjoy watching your work and the attention to detail you show. Glad to see some more posts today.

    Question - I only have basic knowledge of what goes into building an performance engine, and seeing the inside of an engine case painted like that. You mention it is an easier solution than polishing, which I take to mean the other option is polishing all the interior surfaces. What benefit does this give over an unpainted/unpolished case? Better oil return? Less carbon buildup on the surfaces? Less chance for pockets of oil to be retained in places that don't use oil?

    Thanks

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    • Royal Enfield (British, not Indian) had such problems with casting porosity with their crankcases, 350-500 Bullet singles and the Meteor/Constellation/Interceptor 500-650-700-750 twins, all left the factory with internally painted cases to stop oil leaks, or oil leaking through as std.
      They were the only major British factory to do this or suffer such problems.
      All models i mentioned above are also magnificent motorcycle engines.

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      • Originally posted by Tom S View Post
        I very much enjoy watching your work and the attention to detail you show. Glad to see some more posts today.

        Question - I only have basic knowledge of what goes into building an performance engine, and seeing the inside of an engine case painted like that. You mention it is an easier solution than polishing, which I take to mean the other option is polishing all the interior surfaces. What benefit does this give over an unpainted/unpolished case? Better oil return? Less carbon buildup on the surfaces? Less chance for pockets of oil to be retained in places that don't use oil?

        Thanks
        Hi Tom,

        Glad you are getting some enjoyment from all of this.

        Once oil has finished its several functions, the idea is to get it away from the crankshaft where it will cause drag. This is especially true in the air cooled Harley engines such as this one. The flywheel assembly fits rather closely in the cases and getting rid of as much oil as possible will have a noticeable increase in power.

        Many motorcycle engines use a dry sump system such as the one this engine has.

        As a side note, back in the 1930s there was a Morgan 3 wheeled car that was popularly raced. It was powered by a J.A. Prestwich (sp?) V twin motorcycle engine. Some racers warmed the engine with a few practice laps and then drained all the oil before the actual race.

        At a minimum the polishing is done to eliminate casting imperfections and improve drainage as you suspect although in highly stressed areas it may have a benefit to relieve irregularities that could lead to cracking. I don't think it was ever done to a high shine, just a smoothing.

        You may have heard of windage trays used in auto engine oil pans. I recall that it was found that with hard cornering the oil can rise up the inside of the block as much as 14 inches. This is enough to overwhelm the oil control rings and the tray is to help at least reduce this rise.

        The carbon that is formed at the piston rings is very fine and it turns the oil black, but I don't think it can build up anywhere in the crankcase.

        Hope this answers your questions and thank you for your interest!

        Best wishes to ya’ll.

        Sincerely,

        Jim

        "To invent you need a good imagination and a pile of junk" - Thomas Edison

        "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

        Location: Bustling N.E. Arizona

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        • I wasn't thinking dry sump, now that you say that it makes sense. Let the oil do the job, then get it out of the way to reduce drag. Thanks for answering my question.

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          • Thanks for the explanation Jim. I have zero engine building knowledge and always like learning from you wizards. Had many great conversations at the racetrack about the various things engine builders did to free up hidden power. Always found it fascinating, even though it was well outside of my wheelhouse. Thanks for sharing, I like following your threads.

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            • I always thought a windage tray works more like the scraper in HD flywheels, maybe I am wrong.
              I can see where external top end return lines like on shovelhead motors are beneficial. First the oil dumps into camchest, near scavenge pump and away from flywheels, AND it cools the returning oil.

              Comment


              • Hi Everyone,

                When I made this statement, "The carbon that is formed at the piston rings is very fine and it turns the oil black, but I don't think it can build up anywhere in the crankcase", I was picturing carbon build up in the combustion chamber where it is baked on. I realized that in the crankcase it contributes to the formation of sludge that CAN build up - particularly w/o regular oil changes.

                Thank y'all for your interest and comments/questions - keeps me on my toes!

                754:

                I just happen to have a windage tray for a Mopar 440 big block:



                On the left side are four louvers shown here:



                I believe these openings are to gather oil that flies off of the rods in a predictable path. The flat above the louver could appear as a scraper but in order for it to function as one it would have to be much closer to the crankshaft. Plus the tray would have to be deeper to clear the crank. The front and rear of the tray has openings for oil to drain down and away room the spinning crank assembly.

                If a person pictures what high winds do to the waves on an ocean or lake, its easier to see that the crankshaft will do the same to the surface of the oil in the pan, lifting it to interfere with rotation.

                Thank you for mentioning the external lines. I wasn't aware that H.D. used them in production. 1980 was the last year I worked for the company and the service manual I have mentions they used them in late 81 and early 82.

                If these are the lines you are referring to, the manual shows the oil direction as flowing into the crankcase and not away from it. The diagram is not too detailed, but it look like they were trying to scavenge oil from the lifter guides. This is probably because they use hydraulic lifters and have pressurized oil in this area.
                Last edited by jhe.1973; 05-19-2020, 03:36 PM.
                Best wishes to ya’ll.

                Sincerely,

                Jim

                "To invent you need a good imagination and a pile of junk" - Thomas Edison

                "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

                Location: Bustling N.E. Arizona

                Comment


                • Thanks for the pic and explanation.
                  when I mentioned external drain lines, it was never factory, its a hipo trick . Big inches usually trying to eliminate drag and not heat up the oil.
                  big flywheel motors in bikes , likely presents a bigger drag problem than most engines.

                  I am sure it would be easy to demonstrate. Turn a lower end with bearings lubed and no oil in sump by hand..... then pour in 2 cups of oil and try again..
                  Last edited by 754; 05-19-2020, 06:16 PM.

                  Comment


                  • Originally posted by 754 View Post
                    ...........................................big flywheel motors in bikes , likely presents a bigger drag problem than most engines.

                    I am sure it would be easy to demonstrate. Turn a lower end with bearings lubes and no oil in sump by hand..... then pour in 2 cups of oil and try again..
                    You sure have that right!

                    I once was discussing all of this with a well known H.D. performance engine builder and he mentioned something I had not thought of, "Harley engines would make a good two strokes".

                    Considering how little room there is in the crankcase, his observation was dead on.
                    Best wishes to ya’ll.

                    Sincerely,

                    Jim

                    "To invent you need a good imagination and a pile of junk" - Thomas Edison

                    "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

                    Location: Bustling N.E. Arizona

                    Comment


                    • Yes indeed HD used external oil drains for a few years on the Shovelheads. The oil from the rocker boxes which normally drained from the rocker boxes thru a port in the cylinders to then be drawn into the crankcase was changed for the last few years of Shovelhead production.
                      The top end oil which normally ended up being churned by the flywheels on it's way to the gear case was now routed by an external line to the tappet blocks and then to to the gear case. This had many benefits including less drag, lower oil temps, and much less work for for the oil control rings.

                      A small pic of the later model Shovelhead tappet blocks showing the oil drain spigot where the external lines attached.



                      Windage trays can be a separate dedicated item or they can incorporate built in crank scrapers. Crank scrapers can be sourced separately that literally peel the oil from the rotating assembly and are a worthwhile investment for those that already have a windage tray. Clearances are tight so they take a bit of setup time in order to obtain maximum benefit.
                      Lots of design philosophies in the various products available as well.
                      But lots of benefits in keeping the oil away from the rotating assembly and being worked unnecessarily.



                      Great thread Jim and a nicely documented write up. Looking forward to each installment.
                      Home, down in the valley behind the Red Angus
                      Bad Decisions Make Good Stories​

                      Location: British Columbia

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