View Full Version : Twin Cam Oil Pressure Issues


HDF Tech
10-18-2005, 04:08 PM
The TC88 and TC88B engines are good, well thought out designs for your motorcycle. Up to a point that is. The cylinder setup, oil cooling jets, much larger cooling fin area, cylinder base o-ring seal and the new rocker boxes are good improvements. We have been receiving more and more requests for a motorcycle part like the "Cure" for the EVO as oil is still being blown out the breather of the "Twinkie". We are in the prototype stage of some new motorcycle part designs and ideas and will hopefully release a solution soon. On our own 2000 FLHRCI (2KRK) we have had more than a fair share of problems. We were one the first of the cam bearing failures locally barely catching it in time and more recently lost half of the oil pressure for no visible reason. We tore down the cam chest, top end and had a look see and found no apparent cause. We decided to pump it up to 95" and add a 203 SE cam. We ordered a Delkron cam plate and new style OEM oil pump that was supposed to address the return sumping issues of the original motorcycle part design. After assembly with all new parts we found that the new pump would not prime even through back flowing from the filter. We called Gene at Feuling Engineering to get some input as to what he may have come across. He has studied the new oil system and is in agreement that it is a blend of high-pressure low volume and low-pressure high volume in design yet the pump is not capable of meeting the design needs. The oil jets require oil pressure to open and may not get the needed pressure all the time. The bottom line is the oil pump needs help. This is where the Feuling "Super Pump" comes in. The specifications are 40% more flow on the feed side and 60% more flow on the return side. During the initial tear down, we found that the chain tensioner shoes were worn out of tolerance at 20k miles! So, the SE 203 motorcycle cam was changed out for a TW37G and S&S gear set. There are several advantages to gears and very little downside. The advantages are free horsepower, durability and extremely accurate timing. The stock setup cam timing can vary as much as 10ยบ according to some experts. We could feel and see the slop during tear down and assembly. In our opinion it should have been gear drive in the first place. Hypoid gears and properly sized and pitched gears would be no noisier than a so-called silent chain drive. The down side of the gear drive is gear lash. S&S has no control over the quality of the cam plate casting. As a result some gear sets whine or make a ticking sound. S&S has developed a series of under and oversized gears and are working on the procedure to measure the gears in the field. They are also looking into a method of determining the spacing of the cam plate so the customer can specify the proper gear set. After installing all the nice new motorcycle parts we had to chuckle that only stock item left was the Pinion shaft. We primed the pump by pumping oil into the oil filter housing holes and then filling the filter. We still had the cam cover off and the pushrods and tappet blocks out. I was going to get oil pressure BEFORE I assembled this thing again! We spun the motorcycle engine over and we had 20 PSI almost instantly! After buttoning up the top end, we fired it up and at idle oil pressure was at 42 PSI. Blipping the throttle would peg the 80-PSI test gauge. We were due to leave for the annual Bike Talk run that Friday and had to hustle to get some break in mileage on the fresh top end and cams. We checked the motorcycle oil pressure several times and it dropped no lower than the 40 PSI hot. After some test rides, oil pressure was holding steady so we proceeded with the break in and annual Bike Talk ride. While we were working on this problem a customer contacted us asking if we knew of a problem with motorcycle oil pressure! He had the same oil pressure problem and priming problem with a new oil pump motorcycle part. We filled the customer in and he purchased a Feuling pump