I finally pulled down my Knuck engine this April after it pretty much being together since the early 198o’s, I had experienced a slight drop in compression in the front cylinder last August and ran the bike out for a additional 300 + miles to the end of the riding season. When I took the heads off I expected to see a noticeable problem with the front exhaust valve but all of the valves were still in reasonably good shape considering that they were not set up to run with today’s unleaded gas. I had heard a Squeak that seemed to be air escaping by the exhaust valve when checking the compression last fall after I noticed the drop in power. While I was at it I thought I might as well pull the cylinders off and look at the pistons, they were the first set of pistons I had coated back in the mid/late 80s. The pistons looked very good, so good with such a minimal wear on them that I had them re coated, the cylinder bores were clean and still straight. I have had a annoyance with the sound in this engine for decades, and I knew where it was originating from years and years ago. Many most of the parts were replaced when I originally built the engine up, the camshaft was/is a old Tom Sifton 110 series .450 lift cam meant for drag racing use. The stock cam lift was .340 or so, a lot of work/clearancing/checking is needed to install large camshafts in the pre Evolution engines, I had experienced this early on with this engine when I broke a rear exhaust rocker arm because something was not correct for the additional .105 valve lift. What also was taking place was that the new pinion shaft/original pinion gear fitment was not as tight as it should of been and as the years and miles were put on this fitment became looser. The damn thing sounded like the valves were extremely out of adjustment. To correct this I had planned on pulling the complete engine next year and going through the entire thing, well I did not wait……… another 40 + hours I figured were needed in addition to the 20 to pull down/ update, re install the top end and alter the oiling system. All of this besides working 70 hours a week in just over a moth’s time frame. Well it all got done and just in time I might add, I re did the balancing factor while I had it down also, inspected re sized the connecting rod races and inspected but left the main races alone, the bores were still within .0002 of perfect round. Nothing was worn or discolored by heat other than under the piston domes. I have been a STRONG advocate for multi grade premium engine oil for decades and the lack of wear in this engine is a testament to that philosophy. A knucklehead did not receive a great amount of lubricating oil back when it was engineered, less than a Panhead, which was not all that great also. Harley did not start to place full time oil to the crank pin until mid 1973, prior to that just a “squirt”of oil went to the crank pin and bearings as the engine ran, the rest went to the valve shafts. The Panhead started draining the oil down from the heads behind the pistons starting in about 1951-52. This oil additionally helped lubricate the cylinder walls, the Knucks got none. That is why I was simply surprised to see the minimal wear in mine, back when these were built it was not common for the engine to need to be overhauled  in as little as 30,000 miles. We machined down the cylinder base pads in the cases and squared up the engine mount’s while it was down. The heads are now set up to run on today’s shitty gas, the same cam is in it, but I do have the oiling system modified with components from S&S which place a additional 25% more oil through the engine and pull much more from the cylinder heads. The engine had a small issue on the test stand but that is what it is used for, to evaluate/test newly re built engine for any problems. The issue was corrected (a crack in the rear exhaust valve lower cover appeared) The ticking annoying noise is now gone and it is smooth and pulls well once again with the first real ride spanning over 120 miles. Besides the day to day stuff, like broken motorcycles, I will possibly begin the assembly of a 1937 UL that I have the engine and transmission already completed for, this one is to have more of a barn find look to it when it is all said and done, stay tuned. 01f34f66ae2c2f3d2357eddfe79d5993be3d43d0e2

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