Newbie ?, what is a compensator
Road Captain
Joined: Jan 2009
Posts: 739
Likes: 2
From: St. Louis
Elite HDF Member
Joined: Sep 2007
Posts: 4,928
Likes: 69
From: Near Myrtle Beach, SC
Your bike already has the most recent model Screamin Eagle compensator installed at the factory.
Most of the early failures, and it was not epidemic, were with stock compensators on models prior to 2011 due to weak spring design and inadequate energy absorption action. Some owners were having starter clutch and other starter issues as a result. Some would hear a "bang" at start-up. Lots of speculation on what the bang was from, but I believe the consensus was that it was starter gear and starter clutch related. Someone else might chime in with their experience.
Some will say their recently installed Scream'in Eagle compensator failed due to cam wear or due to the main compensator bolt backing out. There has been some concern about inadequate lubrication (primary fluid) reaching the splines between the crank shaft and the compensator assembly. Some have cut groves, but HD has since produced a later model of their compensator with existing lubrication groves and the kit also includes a very thin disk with lubrication groves to help with lube distribution toward the spline.
Not being a mechanic, I am out of my league trying to explain this, but the bottom line is that your 2012 should be fine. It's good to know about the past problems and what can happen, but don't let the compensator threads influence you into believing you have an issue with the compensator on your bike when you probably don't.
Enjoy your new bike.
Most of the early failures, and it was not epidemic, were with stock compensators on models prior to 2011 due to weak spring design and inadequate energy absorption action. Some owners were having starter clutch and other starter issues as a result. Some would hear a "bang" at start-up. Lots of speculation on what the bang was from, but I believe the consensus was that it was starter gear and starter clutch related. Someone else might chime in with their experience.
Some will say their recently installed Scream'in Eagle compensator failed due to cam wear or due to the main compensator bolt backing out. There has been some concern about inadequate lubrication (primary fluid) reaching the splines between the crank shaft and the compensator assembly. Some have cut groves, but HD has since produced a later model of their compensator with existing lubrication groves and the kit also includes a very thin disk with lubrication groves to help with lube distribution toward the spline.
Not being a mechanic, I am out of my league trying to explain this, but the bottom line is that your 2012 should be fine. It's good to know about the past problems and what can happen, but don't let the compensator threads influence you into believing you have an issue with the compensator on your bike when you probably don't.
Enjoy your new bike.
Cruiser
Joined: Sep 2007
Posts: 100
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Grand HDF Member
Joined: Jan 2012
Posts: 4,453
Likes: 2,839
From: Oklahoma
Think of the 4 strokes involved with a 4 cycle engine. Starting with the power stroke, there is a large impulse of power to the crank shaft trying to speed it up. Without the compensator, that strong impulse would be immediately transferred into the drive line and would be felt by the rider. The compensator absorbs some of that energy and releases it after the power stroke. Then the engine "coasts through the exhaust stroke and the intake stroke with relatively little resistance from either process. Then comes the compression stroke and the rotation speed is abruptly slowed by the resistance of the building compression. That abrupt slowing would also be felt by the rider if the compensator didn't absorb some of that also. That puts us back to the next power stroke and the compensator feels and absorbs a reverse of force, during compression, the engine could be "pushed" by the momentum of the machine and the compensator loads in one direction, then after ignition occurs, the engine tries to speed up again and loads the compensator in the opposite direction. This vibration would be very unpleasant, but especially so on a long ride. Imagine putting in a 700 mile day holding on to a vibrating lawn mower handle and getting that buzz through your seat all day long. Not only does the compensator reduce the shock loads on all of the bearings and gears in the drive system, it contributes the comfort level we take for granted.
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Road Master
Joined: Jul 2007
Posts: 914
Likes: 1
From: Republic of Texas
Not being a mechanic, I am out of my league trying to explain this, but the bottom line is that your 2012 should be fine. It's good to know about the past problems and what can happen, but don't let the compensator threads influence you into believing you have an issue with the compensator on your bike when you probably don't.