?? SE Compensator ??
Road Captain
Joined: Jan 2007
Posts: 544
Likes: 0
From: Delaware
I know the IDS on my scoot made a world of difference in the ride. I've been thinking about the comp as I get a fair amount of knocking up front in the primary area and do have that slack in the primary chain that dirtdobber wrote about.
Cruiser
Joined: Nov 2008
Posts: 218
Likes: 1
From: saginaw michigan
Good explanation
Wrong, it does help higher compression engines start smoother and quicker. ESPECIALLY higher compression engines!
On startup, the starter instantly engages and applies huge torque to the rear primary sprocket. That turning force is then transmitted to the front sprocket via the primary chain. At that instant, the top of the chain is being pushed forward by the rear sprocket, not pulled forward by the front sprocket, so all slack in the chain at the bottom is then transferred to the top of the chain. When that happens the chain tensioner gets compressed and a HUGE turning shock is then transmitted to the front sprocket. That huge shock will instantly overcome the light spring in the OEM comp(that's when you hear the loud knock) and the crank will begin to turn and spark fire......Then due to the too weak spring, the chain will then slacken, then tighten again generating yet another but not as forceful turning shock as the first and during the slack time the engine will try to roll backwards due to compression........All in all, what happens is due to the weak spring and ramp design in the OEM comp, the crank does not receive a smooth flutterless twist from the starter. It instead gets slacked, , jerked, rolls backwards, and then jerked hard again several times. The SE comp has a much heavier spring and will absorb much more shock without bottoming out and it also greatly reduce the slack because it doesn't bottom out.
Imagine you are trying to start a pull start lawn mower where the rope isn't wound properly and has a few slack places in it on the crank pully, and when you pull the rope, it first jerks up the slack, then turns the engine a little, then has another few inches of slack, then turns the engine a little more, then a little more slack till then engine finally starts.
It's the same thing.
On startup, the starter instantly engages and applies huge torque to the rear primary sprocket. That turning force is then transmitted to the front sprocket via the primary chain. At that instant, the top of the chain is being pushed forward by the rear sprocket, not pulled forward by the front sprocket, so all slack in the chain at the bottom is then transferred to the top of the chain. When that happens the chain tensioner gets compressed and a HUGE turning shock is then transmitted to the front sprocket. That huge shock will instantly overcome the light spring in the OEM comp(that's when you hear the loud knock) and the crank will begin to turn and spark fire......Then due to the too weak spring, the chain will then slacken, then tighten again generating yet another but not as forceful turning shock as the first and during the slack time the engine will try to roll backwards due to compression........All in all, what happens is due to the weak spring and ramp design in the OEM comp, the crank does not receive a smooth flutterless twist from the starter. It instead gets slacked, , jerked, rolls backwards, and then jerked hard again several times. The SE comp has a much heavier spring and will absorb much more shock without bottoming out and it also greatly reduce the slack because it doesn't bottom out.
Imagine you are trying to start a pull start lawn mower where the rope isn't wound properly and has a few slack places in it on the crank pully, and when you pull the rope, it first jerks up the slack, then turns the engine a little, then has another few inches of slack, then turns the engine a little more, then a little more slack till then engine finally starts.
It's the same thing.
This is the best explanation I have seen in all my searching.
Last edited by chasswartz; Oct 28, 2009 at 06:48 AM.
Road Warrior
Joined: Jun 2008
Posts: 1,602
Likes: 3
From: Southeastern Michigan
From all the reading I've done on both these parts, I'm leaning that way. I know for fact that the IDS dampened a ton of driveline lash on my 07. Probably my best mod so far. So much more refined. AND - like any mod - if that was good, more is better!
I do still question weather or not they work well together. Especially since they are designed for totally different purposes.
That being said, the SE Comp is still on my wish list....
I do still question weather or not they work well together. Especially since they are designed for totally different purposes.
That being said, the SE Comp is still on my wish list....
Cruiser
Joined: Nov 2008
Posts: 218
Likes: 1
From: saginaw michigan
The starter compresses the spring pack to the point it becomes a solid connection. The problem is it is solid in one direction only, as soon as you pass the compression stroke the bottoming out goes away, this is what causes the 'jerky' load to the starter.
Last edited by chasswartz; Oct 28, 2009 at 07:23 AM.
Road Warrior
Joined: Jun 2008
Posts: 1,602
Likes: 3
From: Southeastern Michigan
The stock compensator turns on a ramped cam that is limited by the pulley housing (otherwise it would just roll over onto another ramp). When the cam hits this limit - it "bottoms out".
Cruiser
Joined: Nov 2008
Posts: 218
Likes: 1
From: saginaw michigan
From all the reading I've done on both these parts, I'm leaning that way. I know for fact that the IDS dampened a ton of driveline lash on my 07. Probably my best mod so far. So much more refined. AND - like any mod - if that was good, more is better!
I do still question weather or not they work well together. Especially since they are designed for totally different purposes.
That being said, the SE Comp is still on my wish list....
I do still question weather or not they work well together. Especially since they are designed for totally different purposes.
That being said, the SE Comp is still on my wish list....
Road Warrior
Joined: Mar 2008
Posts: 1,783
Likes: 10
From: Oh
Look at the two pics below and notice the new SE compensator has clutches in it and the old one (you have) does not. The torque from the crankshaft makes the old compensator take off up the ramp bottoming on the ramp when you hit the starter. The clutches on the new compensator takes this load thereby eliminating the fast ramp up on the old compensator.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider
Verdad Gallardo
Cruiser
Joined: Nov 2008
Posts: 218
Likes: 1
From: saginaw michigan
springs not clutches
Those are springs not clutches. The stock comp also has springs in the roter housing extension, just much lighter springs. The SE has 3 sets of springs {wave washer type] each one progressively stronger. I have not taken the springs out of the old comp for inspection, but they look much weaker than the SE comp.
Last edited by chasswartz; Oct 28, 2009 at 07:24 AM.
Road Warrior
Joined: Mar 2008
Posts: 1,783
Likes: 10
From: Oh
Those are springs not clutches. The stock comp also has springs in the roter housing extension, just much lighter springs. The SE has 3 sets of springs {wave washer type] each one progressively stronger. I have not taken the springs out of the old comp for inspection, but they look much weaker than the SE comp.
I have added pics of my stock compensator. Notice the TWO springs inside, one thicker than the other. These are what take the initial load off the crank and are not heavt enough. I also added the parts page for the new compensator which clearly shows the difference in the two.
Bottom line, it's better.