SE Compensator
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,310
Likes: 6,328
From: Honah Lee
Yes, grinding on hot starts usually IS the compensator. The original comps would fully compress those weak assed springs on the compression stroke during cranking then recoil back throwing the starter drive out of the ring gear then back again, causing the grinding. It's why it's hot starts where this happens since the heat soaking makes it a bit harder to turn over. If your bike still has the original compensator, it needs replaced regardless. Those early comps would break and wear out quickly. They were pure junk, why H-D didn't find that out during development is beyond me. Mine did a grinding when hot starting once. After the SE it's never done it since and it has been hotter than hell on some starts.
In some cases, the starter drive gets cracked from those junk early compensators causing it to throw out so it is possible it will need replaced. Also check the starter ring gear for missing teeth.
In some cases, the starter drive gets cracked from those junk early compensators causing it to throw out so it is possible it will need replaced. Also check the starter ring gear for missing teeth.
The starter small gear is a sprag clutch. It cannot slip. It drives with pins held against a shoulder. If the motor starts and the starter is still engaged, the gas motor outruns the electric starter and the pins run up the ramp which disengages the gear. This prevents the starter from being thrown apart by centrifugal force. The only thing this does if starter slips this way is to make a click hum noise.
However, I do realize there is no way to beat a tin man at their game. I will close with the starter and gear does not know the difference in the load put on it by the cylinder loading up with compression or the compensator load up 20 degrees of turn half way or on to full 45 degrees of turn lockup.
Last edited by Jackie Paper; Aug 6, 2018 at 07:42 AM.
Seasoned HDF Member
Joined: Oct 2012
Posts: 11,198
Likes: 3,028
From: St.Louis Mo.
Just my opinion but what holds the starter gear is a electrical magnet solenoid. When a battery is so weak it does not crank, that is the click you hear where it is trying to engage the starter. (Modern cars with their fancy electronics don't even click anymore since they know and have a setting not to even try if the voltage is too low) Anyway, when the weak battery does start cranking, it is so weak, the loaded cylinder kicks the weak starter back or voltage drops so low, the solenoid drops out and pulls starter gear out. Has nothing to do with compensator spring. If the spring was that weak, it would simply let the compensator wind up to lock which is only 45 degrees or so.
The starter small gear is a sprag clutch. It cannot slip. It drives with pins held against a shoulder. If the motor starts and the starter is still engaged, the gas motor outruns the electric starter and the pins run up the ramp which disengages the gear. This prevents the starter from being thrown apart by centrifugal force. The only thing this does if starter slips this way is to make a click hum noise.
However, I do realize there is no way to beat a tin man at their game. I will close with the starter and gear does not know the difference in the load put on it by the cylinder loading up with compression or the compensator load up 20 degrees of turn half way or on to full 45 degrees of turn lockup.
The starter small gear is a sprag clutch. It cannot slip. It drives with pins held against a shoulder. If the motor starts and the starter is still engaged, the gas motor outruns the electric starter and the pins run up the ramp which disengages the gear. This prevents the starter from being thrown apart by centrifugal force. The only thing this does if starter slips this way is to make a click hum noise.
However, I do realize there is no way to beat a tin man at their game. I will close with the starter and gear does not know the difference in the load put on it by the cylinder loading up with compression or the compensator load up 20 degrees of turn half way or on to full 45 degrees of turn lockup.
Thread Starter
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Road Warrior
Joined: Sep 2012
Posts: 1,253
Likes: 482
From: MA
Hm, interesting. It seems to be about 50/50 comp related or starter clutch related depending who I ask and what I read.
Since it only does it on HOT starts (like stopping for gas and leaving) does that direct me to one or the other? Would the comp care if its hot? Would the starter clutch? Would the battery?
If its the first start of the day, or I eat lunch (let it sit 30 min) it starts up just fine, no issue at all.
Not arguing with anyone, just trying to learn. Thanks for the help!
Since it only does it on HOT starts (like stopping for gas and leaving) does that direct me to one or the other? Would the comp care if its hot? Would the starter clutch? Would the battery?
If its the first start of the day, or I eat lunch (let it sit 30 min) it starts up just fine, no issue at all.
Not arguing with anyone, just trying to learn. Thanks for the help!
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,310
Likes: 6,328
From: Honah Lee
What happens when it sets and cools off is that odd loaded cylinder that is full of an explosive mixture evaporites off rather than exploding kicking quite often in the wrong direction with a bang that drives everything backward making a hard clunk. Mine does it once in a while and has popped the Softail oil dipstick plug out and made smoke out the air filter. (if the battery is weak, it happens more since a good battery can overcome this kickback) If the mechanical compensator was worn out, you would have your problem all the time. Now the compensator does make more noise when hot but that is because of the hot oil. However, do not try to fix that with heavy oil. That will just make first gear clunk worst and actually affect how it shifts since these transmissions need to spin to shift correctly since the drive is actually 6 recess lugs on each gear. (gears are always engaged)
Since you brought up and I guess most are saying I am arguing, done here before I **** off the tin men. Your comp just could be worn on the drive faces but that is not what jumps at me in what you said in post one. My opinion is just that based on 46 years of shipbuilding mechanical engineering. Also, a sideline on electrical to support my mechanical. Been working on bikes all this time but that is just my hobby,
Since you brought up and I guess most are saying I am arguing, done here before I **** off the tin men. Your comp just could be worn on the drive faces but that is not what jumps at me in what you said in post one. My opinion is just that based on 46 years of shipbuilding mechanical engineering. Also, a sideline on electrical to support my mechanical. Been working on bikes all this time but that is just my hobby,
Last edited by Jackie Paper; Aug 6, 2018 at 11:04 AM.
Grand HDF Member
Joined: Mar 2011
Posts: 4,816
Likes: 1,320
From: Good roads, cold beer
Yup, another compensator thread/question.
2008 road glide with 36k miles. Hard clunk/grind on hot starts only.
Bought a SE compensator and read this thread https://www.hdforums.com/forum/touri...w-pics-12.html
but all of the pictures are gone.
Does anyone have the pictures saved by chance?
Is there a final answer on what fluid to run, and if to grind grooves in the new sprocket or not?
what else do I need to buy, if anything?
i have a big trip coming at the end of the week so I need to get this done, and done right. Any help, advice, pictures, suggestions and tips etc is greatly appreciated! Thank you!
2008 road glide with 36k miles. Hard clunk/grind on hot starts only.
Bought a SE compensator and read this thread https://www.hdforums.com/forum/touri...w-pics-12.html
but all of the pictures are gone.
Does anyone have the pictures saved by chance?
Is there a final answer on what fluid to run, and if to grind grooves in the new sprocket or not?
what else do I need to buy, if anything?
i have a big trip coming at the end of the week so I need to get this done, and done right. Any help, advice, pictures, suggestions and tips etc is greatly appreciated! Thank you!
Also, hit Youtube and search for your issue....it helps when asking questions here on how to proceed w/ a fix. JMO
Also, if you can use a phone and film a video and post, prob get more useful replies. As stated, seems multiple things can create what you are describing.
I have an 08 and recently put in a new SE comp....and then after reading also did the starter clutch. Not sure I needed the latter, but, was being proactive and the part was relatively cheap and it wasn't hard to do.
Last edited by F150HD; Aug 14, 2018 at 03:09 PM.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
If your comp is bad there is no doubt in your mind. It's a hell of a racket while riding coming out of the primary. Been there, done that. And the spring on mine was just out of spec on my 07. That said your dealer can check your current compensator if you really believe yours is bad. I also had a lot of metal shavings in my primary oil. I mean a lot. Replaced it with the SE comp and life was good until I sold the bike.
Road Captain
Joined: Jun 2012
Posts: 574
Likes: 156
From: Big Sky Country
Lots of information here, much more than some other threads on this topic--thanks all. Not to go off on a tangent, but it's interesting to me that some have better luck engaging starter before fuel pump finishes running/reaches operating pressure. I have the opposite situation where bike seems to start best when I let it finish, just as long as the battery is in good condition. And I always hold starter button and am careful not to release early... My (mostly) stock 96 w/stage 1 intake/exhaust/tune sometimes struggled just a bit when hot, but always fired right up so long as I kept starter engaged. Bike is a 2011, however, which I was led to believe had the upgraded/SE compensator new from factory.
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