See the attached notice from Baisley...
Jacques
The attachment says that the valve train will run quieter with increased oil pressure supplied to the lifters. That may be true under certain circumstances; say your lifters are worn out, manufactured incorrectly or designed specifically to be run at a higher pressure. The stock Twin Cam lifter is the same part number that is run in the Sportster. The hot oil pressure spec for an XL @ 2,000 rpm is 10 to 17 psi. It is my experience that 17 psi is an optimistic number for these engines. BTW as far as the basic layout is concerned, the XL engine is very similar to the earlier Twin Cam.
Experience with my personal ‘97 Buell S1 running Branch heads and Andrews cams is that you could spin it at 6,500 rpm all day long, or until it came apart, without the lifters bleeding down; folks, this engine makes about 14 psi of pressure when hot. My BS alarm starts to rattle a little when I hear claims that an OEM lifter running near 30 psi of oil pressure could use more pressure to stay pumped up. I’ll bet a can of Diet Coke that these lifters would stay pumped up all day long running big cams with high seat pressures on about 5 psi of oil pressure.
The attachment also says that “Models with hydraulic chain tensioners will see a benefit in their ability to maintain pressure, on the chains, reducing unloading on decel and cam nose over.” My BS alarm doesn’t make any noise on this point because the hydraulic tensioners and roller chain assembly is new, and has not been time tested over the decades that the lifters have.
A little background on the “decal” and “noseover” referred to in the attachment. This describes conditions that result in the normally unloaded section of the cam chain becoming loaded; in this case the section of cam chain under the chain tensioner shoe. The early spring loaded cam chain tensioners had to be “oversprung” in order to maintain adequate pressure throughout the cam chain’s service life. Needless to say, this resulted in accelerated wear. Another thing that happens with spring tensioners is that they do not have enough tension to cope with noseover when run with aggressive cam profiles and valve springs; the tensioners simply get pushed out of the way on noseover. This isn’t a real big deal with unworn components, but as the chains and sprockets wear, the backlash becomes substantial and valve control is reduced. This becomes evident as the machine accumulates mileage and the valve train gets louder. It is most noticeable when the engine quiets down after new chains, sprockets and tensioners are installed.
Unlike spring tensioners, the hydraulic tensioners maintain a significantly reduced, constant pressure which extends the service life of all related components. By its nature, the hydraulic tensioner is better equipped to manage noseover than are spring tensioners. The question is; how much oil pressure does it take to manage noseover in a high performance application? The next question is; what affect will increased oil pressure have on the service life of the tensioner shoes and chains?
If the hydraulic tensioners prove to be sensitive to noseover when run with aggressive cams and valve springs, the answer may be to jack up the oil pressure, or another answer might be to modify the bleed off rate and timing while continuing to run lower oil pressure. The jury is still out on the hydraulic cam chain tensioners, but it shouldn’t take much longer to get them sorted out.
If you subscribe to the theory; “if a little is good then more must be better”, and jacking up the oil pressure makes you feel good, then crank it up! If lower oil pressure makes you nervous and you own a Sportster, try Prozac….amateurzac works good for those of you that don’t yet have your motorcycle endorsement.
djkak
Author
Topic: Baisley LMR-02 oil spring (Read 22378 times)