Starter clutch or compensator
Outstanding HDF Member
Joined: Aug 2012
Posts: 3,217
Likes: 90
From: Detroit
You had the battery load tested, or checked the voltage during cranking?
Starter motors lose power when they are hot, so that can be when the first symptoms of inadequate power supply show up. Could be a weak battery, battery cables that are going bad, bad connections where the negative cable connects to ground, or where the plus cable connects to the starter motor. It could be anywhere along the power path, including the solenoid contacts.
The engine fires before top dead center (which will try to turn the engine backwards at cranking speeds), so if the starter motor isn't strong enough to push the engine through that point, the engine will indeed kick over backwards, against the starter. It sounds like that's what is happening in the original video
Starter motors lose power when they are hot, so that can be when the first symptoms of inadequate power supply show up. Could be a weak battery, battery cables that are going bad, bad connections where the negative cable connects to ground, or where the plus cable connects to the starter motor. It could be anywhere along the power path, including the solenoid contacts.
The engine fires before top dead center (which will try to turn the engine backwards at cranking speeds), so if the starter motor isn't strong enough to push the engine through that point, the engine will indeed kick over backwards, against the starter. It sounds like that's what is happening in the original video
Stage I
Joined: Mar 2016
Posts: 1
Likes: 0
From: WV
Go with the SE Compensator
I had the same Hot Start issues with my 2008 Fatboy. The compensator looked fine, but after reading about the experience of others, I put on the SE compensator upgrade. Starts better than new now. Improved low end torque as well.
Road Warrior
Joined: Dec 2010
Posts: 1,629
Likes: 46
From: East Hartford, CT
When mine was doing that I changed out the starter clutch with an allballs one on ebay.
Worked better till one day started taking it's time to start.
I switched out the relay and it was better,
that was last year, this year I have a new Allballs 1.4 Kw heavy duty starter with new #4 welding cable battery cables..
Problem solved. Put the original starter on the shelf. (spare parts division)
Worked better till one day started taking it's time to start.
I switched out the relay and it was better,
that was last year, this year I have a new Allballs 1.4 Kw heavy duty starter with new #4 welding cable battery cables..
Problem solved. Put the original starter on the shelf. (spare parts division)
Nothing yet, I will post in here with my findings.
I just ordered a new front wheel and will take the bike off the ground when that gets here and open up the primary then!
I just ordered a new front wheel and will take the bike off the ground when that gets here and open up the primary then!
Road Captain
Joined: May 2014
Posts: 593
Likes: 7
From: Wausau, WI
I have the same issues on my 09 fatbob. Only when hot and only when there is people around to watch me look stupid. It's very infrequent. The previous owner had issues as well and had the fuel pump changed and it seemed to alleviate the issues. But then it started to shop up once in a while. My battery is original, but I figured it was still strong, until this past weekend when it coughed at me, and I had to hold the starter button down for a while because it didn't want to fire. I could tell the battery was getting weak as it turned over 3 maybe 4 times... Guess its time for a new battery.
But, as a side note, it does seem to improve if you don't let the pump prime when its hot and I started to hold the starter button down longer than I normally did...
But, as a side note, it does seem to improve if you don't let the pump prime when its hot and I started to hold the starter button down longer than I normally did...
Supporter
Joined: Jan 2007
Posts: 15,788
Likes: 5,625
From: along the shore of Mishigami
My vote is on the starter clutch and don't be so quick on releasing the start button. The flywheel has got to make a couple of revolutions for the crank position sensor to read the notches in the flywheel to trigger the firing sequence.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
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
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,586
Likes: 6,435
From: Honah Lee
It's not the starter sprag clutch. The gas motor has to run faster then the starter to out run those drive pins. It is not possible for them to slip as long as the starter motor is driving fwd in a cranking condition.
Road Master
Joined: Apr 2008
Posts: 897
Likes: 10
From: Oregon
Originally Posted by RIPSAW
It's not the starter sprag clutch. The gas motor has to run faster then the starter to out run those drive pins. It is not possible for them to slip as long as the starter motor is driving fwd in a cranking condition.