Vincent Motorcycle Engines. Technical Informationeach can be enlargedAndy Hopkins Die Cast Rapide. Engine. Comet Timing Gear Group. Revised 1. Gwilym. Davies Higher. I hesitate to Constantly remind you. Proceed at Your Own Risk. Engine Condition by. Max Lambky 1. 252. At one time or another. Vincent owners find it necessary to assess the condition of. The reasons for engine inspection are many. If the. inspection is made prior to the purchase, it could be a major issue. Another reason would be. A pretty good assessment as to engine condition can be obtained. Using your. five senses can result in a fairly accurate condition appraisal. If. the engine is a running unit, a lot can be deduced by simply. Static sound tests and. Crankshaft big ends. Bluish smoke. from the exhaust pipe during hard acceleration is most likely caused. Transmission parts and their wear can also sometimes be determined. A whining noise. jumping out of gear, or poor shifting characteristics, are all. The engine. running in a static mode, can easily be checked by using a common. Place the working end of the screwdriver. Engine parts that. Head. cylinder muff, timing cover, primary cover, and engine cases should. Better yet than the screwdriver, a physicians. A thorough visual inspection of engine and parts should be conducted. Married parts, such as crankcase to crankcase, primary. Excessive leakage can sometimes be caused by warped or. A visual inspection of the oil filter and the. Metallic particles can tell you a lot as to engine condition. The. oil filter after a period of use, will always have some metallic. Cam timing gears and. With the exhaust pipes removed, the exhaust. An oil. saturated carbon deposit on the port is an indication of leaking. Dont limit your visual. A thorough cosmetic inspection is. Engine finish on. Shadows and covers on Ds, as well as broken fins, can add to the. Rounded hex head. Feel and touch is also used to determine the condition of some. One common check is performed by removing the rocker. Grip the rocker in the area of the push. Try moving the rocker. If movement is detected its more than. This isnt good, but is pretty common in engines that have. Another feel check is one that determines the. This is done by checking for excessive back. Remove rocker covers and back off all rocker adjusting screws. Remove cam cover inspection plate. Rotate the fiber or nylon magneto. Too much rotation. Repair can be as simple as replacing crankshaft half time. Often early aluminum or brass gears will require. The same goes for the fiber mag drive gear. All of. these gears are prone to wear. The magneto automatic advance is checked as to its condition in the. With the magneto point cover removed, turn the magneto, expanding. The springs to the fly. If you get a quick. Magneto spark should be. Remove spark plugs. Take an old set of sparkplugs. Tape over gapped sparkplugs hex nut to ground with duct tape. With. the engine out of gear, kick it over. Both sparkplugs on the twin. A yellowish, or. no spark, indicates that a rework of the magneto will be necessary. A routine and most common practice in determining engine condition. To. do either of these tests with confidence you must first understand. For. example on a twin, if you increased the compression ratio from a 7. The leak down method is. The. problem with determining engine condition with the use of a. The unknown being. Compression of the cylinder during tests starts at the. Cam timing, such as it is. Vincent twins, leads to false readings. A reading of say. The Vincent owner who is. Compression checks are made valid only when valve. Its a good idea for the new owner of a Vincent who isnt familiar. Beast, to employ a person of proven capability whos been. Vincents for awhile to test ride and give his input on the. Discussion. of Engine Balancing When I was, I think, 1. I bought a JD Harley Davidson motor from my motorcycle. Burt Mc. New. Spent 1. JD, but it did. come with a manual. Strangely enough I still remember the pages that. JDs crankshaft. It explained two. It went on to say. The weight of. the bob weight should be equal to the weight of all the rods, roller. Placed the. trued crankshaft on the parallel bars, drill holes as necessary in. I would guess as the pistons were quite heavy. Balancing of engines is pretty much a black art. Percent factors. of balance are only used in V twin engines and parallel twins. These. are the only engines that require a bob weight to balance the. Opposed cylinder engines, multi cylinder V engines. The crankshafts are so. There are 2 forces in balancing an engine that are corrected. The first being the kinetic energy when spun, which is a direct. The next is the. dynamic balance of the crankshaft, which is the movement forces. For practical purposes, a Harley. Davidson V twin with the split rod has its rod and piston mass. In other words, its a waste of time to pay a. Do to the fact of the mass on a single. Now, the Vincent can benefit slightly by blueprinting the. Equal balance. of the pistons and rods on separate planes alleviates some of. You wouldnt think that a flywheel, being balanced, would have. Its pretty unbelievable, but they. A flywheel on an automobile, one half inch thick requires. Both sides can correct the dynamic balance, but cannot correct. The kinetic balance can be corrected by. A dynamic balancing machine has adjustable spring pensioners to. Both knife rollers and. For instance, a straight eight Buick. This would give. the most sensitivity to the machine as to its dynamic balance. Both kinetic and dynamic balance factors are corrected usually. V6 engines are the most cantankerous of all to. Dont ask me why, its too confusing for this wrench. Now that I probably have everyone confused, I know I am. Im. going to retire. Max Lambky. Blueprinting a Vincent Connecting Rod. Properly blueprinting a pair of Vincent connecting rods is easier. If youre privy to a rod stash, meaning more than two, the first. Before you start to. Forgings varied, not due to forging procedures using the same. Variations were caused by various forming dies. I. believe as many as four die manufactures were utilized in the. Vincent Works. If you dont have a. The initial. steps in blueprinting the rod is its disassembly. Of course Im. referring to used rods, not new rods. Push the big end bearing races. Clean the two rods thoroughly, especially the big end. Discard the bushings and the big end outer. In a proper blueprint these items are made new. With a bore. gauge, check the roundness of the big end bearing bore of the rod as. Check the diameters of the. These dimensions are important for proper crush. The little end bushing bore is not. If the big ends are found out of round, its best to. Some fellows. hone the rod round, hard chrome the race, and regrind to achieve. Id only recommend this for engines that. The desired. interference fit between the outer big end race and the big end of. The cylindrical bore of the rod isnt equal in. The portion where the rod I beam attaches to the big end. Approximately 2. 10o of the big end. Bushing. interference fit of the little end should be. This is enough. interference fit to prevent any turning of the bushing in its bore. Any less than. 0. Before installing the big end race and the small end bushing, the. X and Y axis. For this to. If the. rods are the same length, i. Two pins. approximately six inches long, one being turned on the lathe to. Simply achieve. a slide fit through both rods with the two sized pins, where there. If you can do this, the rod. X and Y are accurate. Next, the rods should be checked for equal length. If the two small.