Harley Davidson Forums

Touring Models Road King, Road King Custom, Road King Classic, Road Glide, Street Glide, Electra Glide, Electra Glide Classic, and Electra Glide Ultra Classic bikes.
Sponsored by:
Sponsored by:

Leak Down Test

Thread Tools
 
Search this Thread
 
Old Dec 15, 2020 | 07:46 PM
Share
  #1  
skydude426's Avatar
skydude426
Thread Starter
|
Club Member
15 Year Member
Liked
Loved
Community Favorite
Joined: Sep 2010
Posts: 1,690
Likes: 457
Riders Club Member
Default Leak Down Test
Hey Everyone,

I’m wondering what the conscious is on the right way to do a leak down test. With the engine warm or with the engine cold, and why?

Thanks in advance and Merry Christmas.
 
Reply
0
Old Dec 15, 2020 | 09:04 PM
Share
  #2  
Cogswell's Avatar
Cogswell
Road Captain
5 Year Member
Liked
Loved
Top Answer: 1
Joined: Feb 2018
Posts: 514
Likes: 263
From: Appalachia
Default
Why not just do both and compare the results, keeping in mind parts will expand and clearances typically diminish when hot.
 
Reply
0
Old Dec 15, 2020 | 09:32 PM
Share
  #3  
skydude426's Avatar
skydude426
Thread Starter
|
Club Member
15 Year Member
Liked
Loved
Community Favorite
Joined: Sep 2010
Posts: 1,690
Likes: 457
Riders Club Member
Default
Originally Posted by Cogswell
Why not just do both and compare the results, keeping in mind parts will expand and clearances typically diminish when hot.
I plan on it. I was just after the opinion of those who know such things in a effort to continue learning about my bike.
 
Reply
0
Old Dec 16, 2020 | 04:41 AM
Share
  #4  
General Hangover's Avatar
General Hangover
Cruiser
5 Year Member
Liked
Loved
Community Favorite
Joined: Mar 2017
Posts: 196
Likes: 91
From: Hamburg
Default
I'm using the leakdown tester from Jims. Have a look a the instruction page from JIMS. Even it's not explained why you shall do it hot, it's a very comprehensive guide.

Hope it helps!
 
Reply
0
Old Dec 17, 2020 | 10:16 AM
Share
  #5  
Geoff1200's Avatar
Geoff1200
Advanced
Joined: May 2007
Posts: 79
Likes: 17
From: N.E. Fl.
Default
I've found over the years, Harleys have a high leak down rate (compared to automobile engines) Still seem to run ok...
 
Reply
0
Old Dec 17, 2020 | 06:45 PM
Share
  #6  
Keithhu's Avatar
Keithhu
Seasoned HDF Member
15 Year Member
Liked
Loved
Community Favorite
Joined: Sep 2009
Posts: 17,145
Likes: 6,168
From: SE Michigan
Default
Originally Posted by Geoff1200
I've found over the years, Harleys have a high leak down rate (compared to automobile engines) Still seem to run ok...
True. The service manual on late model bikes say up to 25% is OK.
 
Reply
0
Old Dec 17, 2020 | 07:24 PM
Share
  #7  
Dseago1969's Avatar
Dseago1969
Road Master
5 Year Member
Liked
Loved
Community Favorite
Joined: Jan 2020
Posts: 856
Likes: 373
From: Duke City, NM
Default
I always did it cold. Sometimes it’s a non run situation or new engine pre-install so warming up isn’t an option at best slightly warm. It sucks pulling plugs on a hot plug. Most specs you find should be cold numbers.
 
Reply
0

Trending Topics

Old Dec 18, 2020 | 05:05 PM
Share
  #8  
1993FXSTS's Avatar
1993FXSTS
Cruiser
10 Year Member
Liked
Loved
Joined: Jan 2014
Posts: 147
Likes: 61
From: Mulkeytown, IL
Default
Originally Posted by Keithhu
True. The service manual on late model bikes say up to 25% is OK.
Damn, that's a lot! I seem to recall seeing between 5 and 10 percent on my Evo.
 
Reply
0
HD Forum Stories

The Best of Harley-Davidson for Lifelong Riders

story-0

7 Times Harley-Davidson Chucked Tradition Out the Window

 Verdad Gallardo
story-1

7 Surprising Harley-Davidson Products that Are Not Motorcycles

 Verdad Gallardo
story-2

8 Best Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-3

10 Worst Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-4

Killer Custom's Jail Break Is The Breakout That Refused to Blend In

 Verdad Gallardo
story-5

Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

 Verdad Gallardo
story-6

Harley-Davidson Reveals Super Cool Cafe Racer Concept

 Verdad Gallardo
story-7

Engraved Rebellion: Inside Bundnerbike's Glam Rock II

 Verdad Gallardo
story-8

10 Motorcycles You Should Never Buy

 Joe Kucinski
story-9

10 Things Harley-Davidson Needs to Fix in 2026

 Verdad Gallardo
Old Dec 18, 2020 | 05:43 PM
Share
  #9  
Keithhu's Avatar
Keithhu
Seasoned HDF Member
15 Year Member
Liked
Loved
Community Favorite
Joined: Sep 2009
Posts: 17,145
Likes: 6,168
From: SE Michigan
Default
Originally Posted by 1993FXSTS
Damn, that's a lot! I seem to recall seeing between 5 and 10 percent on my Evo.
Yep. I have a screen shot of the 2018 service manual somewhere. If I'm lyin' I'm dyin'!

Edit - found it in the 2020 service manual:

 
Last edited by Keithhu; Dec 18, 2020 at 06:00 PM.
Reply
1
Old Dec 18, 2020 | 09:22 PM
Share
  #10  
hattitude's Avatar
hattitude
Seasoned HDF Member
15 Year Member
Community Builder
Community Favorite
Top Answer: 10
Joined: Sep 2008
Posts: 14,148
Likes: 11,221
From: San Diego, CA
Default
Originally Posted by Keithhu
Yep. I have a screen shot of the 2018 service manual somewhere. If I'm lyin' I'm dyin'!

Edit - found it in the 2020 service manual:

That's crazy.....

In my 2001 & 2003 Service Manuals it calls for a max of 10%....
 
Reply
0



Advanced Search
Reply Closed Thread Share
Forum Jump

All times are GMT -5. The time now is 06:40 PM.

story-0
7 Times Harley-Davidson Chucked Tradition Out the Window

Slideshow: Harley-Davidson built its reputation on nostalgia, but every so often, the company took a hard left turn into the future.

By Verdad Gallardo | 2026-05-20 11:18:19


VIEW MORE
story-1
7 Surprising Harley-Davidson Products that Are Not Motorcycles

Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.

By Verdad Gallardo | 2026-04-29 16:50:35


VIEW MORE
story-2
8 Best Harley-Davidson Motorcycles Ever

Slideshow: Not every Harley gets it right, but these are the ones that genuinely earned their reputation.

By Pouria Savadkouei | 2026-04-15 14:23:21


VIEW MORE
story-3
10 Worst Harley-Davidson Motorcycles Ever

Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.

By Pouria Savadkouei | 2026-04-01 20:01:09


VIEW MORE
story-4
Killer Custom's Jail Break Is The Breakout That Refused to Blend In

Slideshow: Killer Custom's "Jail Breaker" build focuses more on stance and visual aggression than mechanical overhaul.

By Verdad Gallardo | 2026-03-18 19:20:32


VIEW MORE
story-5
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.

By Verdad Gallardo | 2026-03-07 16:15:30


VIEW MORE
story-6
Harley-Davidson Reveals Super Cool Cafe Racer Concept

Slideshow: Harley-Davidson's new RMCR concept revives the café racer formula with modern hardware-and it may be exactly the reset the company needs.

By Verdad Gallardo | 2026-03-04 12:23:37


VIEW MORE
story-7
Engraved Rebellion: Inside Bundnerbike's Glam Rock II

Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.

By Verdad Gallardo | 2026-02-24 18:19:44


VIEW MORE
story-8
10 Motorcycles You Should Never Buy

Slideshow: There is no shortage of great motorcycles to buy, but we would avoid these ten.

By Joe Kucinski | 2026-02-19 14:50:51


VIEW MORE
story-9
10 Things Harley-Davidson Needs to Fix in 2026

Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.

By Verdad Gallardo | 2026-01-13 18:33:17


VIEW MORE