Compression loss - Harley Davidson Forums

Engine Mechanical Topics Discussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.

Compression loss

  #1  
Old 10-12-2017, 09:47 AM
rjz500
rjz500 is offline
New Member
Thread Starter
Join Date: Oct 2017
Location: SAN BERNARDINO CA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default Compression loss

2014 DYNA FXDWG 103, 62,000 MILES: Riding down the freeway at 70 mph feels like somebody turned off the fuel, I would roll the throttle back and forth a few times and it would come back to life. It did it several more times, thought it was the fuel pump, but you can hear the pump pressurize when you turn on the ignition. Leaving work, got a few miles down the road and it started to do it again, this time I couldn't get it to come back to life. Sitting on the side of the road I cranked it over and it was like one cylinder had no compression. I tried it several more times and then it turned over with no compression, finally started up real rough and then started to knock real loud. The engine never made any noise, it was always surprisingly quiet. I pulled the rocker boxes and lifters, the valve springs look intact, lifters pump up good, cam lobes look very good (hardly any wear patterns), push rods straight. I was thinking that it could be the ACR's, but that wouldn't explain the loud knock. I haven't tried turning it over since I heard the knock.
 
  #2  
Old 10-12-2017, 09:53 AM
rjz500
rjz500 is offline
New Member
Thread Starter
Join Date: Oct 2017
Location: SAN BERNARDINO CA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default Newbie

Did I post this in the wrong forum?
 
  #3  
Old 10-12-2017, 10:59 AM
djl's Avatar
djl
djl is online now
Ultimate HDF Member
Join Date: Jun 2006
Location: san antonio
Posts: 8,607
Thanks: 0
Thanked 350 Times in 321 Posts
Default

We can get to the knock later but until you do a compression check, you don't know whether you have compression or not, so let's start there.
 
  #4  
Old 10-12-2017, 11:45 AM
Max Headflow's Avatar
Max Headflow
Max Headflow is online now
Ultimate HDF Member
Join Date: Dec 2005
Location: poway
Posts: 5,960
Thanked 843 Times in 703 Posts
Default

6 minutes is would be pretty quick response time.. Have you looked at the plugs?

Compression and fuel pressure need checking.. Simply because the pump runs is not a good indicator of fuel pressure.
 
  #5  
Old 10-12-2017, 02:50 PM
rjz500
rjz500 is offline
New Member
Thread Starter
Join Date: Oct 2017
Location: SAN BERNARDINO CA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default Follow-Up

Compression check, should have thought of that first. I will pickup a compression tester tomorrow, already have the fuel pressure gauge. Guess I will be busy Saturday. Thanks for your input, I will post my results soon. Thanks again.
 
  #6  
Old 10-13-2017, 06:01 AM
Hillsidecycle.com's Avatar
Hillsidecycle.com
Hillsidecycle.com is online now
Sponsor
Join Date: Dec 2007
Posts: 11,113
Thanked 226 Times in 190 Posts
Default

Compression release went sour, lost a lifter roller?
Only guesses.
Scott
 
__________________
HILLSIDE MOTORCYCLE & MACHINE, INC.
HARLEY-DAVIDSON SPEED & SERVICE CENTER
5225 SOUTH MAIN ST., MUNNSVILLE, N.Y. 13409
Sales/Support 315-495-6650
www.hillsidecycle.com
Walk-in Retail Counter
Complete H-D Machine Shop
Case & cylinder boring
Complete Cylinder Head Shop
High-Performance Engine Kits
Super-Flow 600 Bench
Crank Rebuilding
Direct Link & PowerVision Tuning
Goodson HD Tooling Manufacturer
Maxton Mile World Record
OVER 30 YEARS OF H-D ENGINE BUILDING.
See us on Facebook.
  #7  
Old 10-13-2017, 10:24 AM
2009blackpearle's Avatar
2009blackpearle
2009blackpearle is offline
Road Master
Join Date: Dec 2008
Posts: 820
Thanked 14 Times in 13 Posts
Default will need to unplug acr wire

remember when u do the test u will have to test with the acr working and then unplug it for the second test to see if its stuck open. not sure how the 2014 are wired I added acrs to my 2009 had to move wires around fuse box, not sure if taking fuse out of panel for fuel pump would kill power to them or not, in my case the rewire ties them to fuel pump, then purple wire to ecm modual activates them when starter hit. would be easier than pulling tank off, Ive always had mine off doing work so it was already off in my case . maybe pro drag or scott would know easier way to disable them without tank coming off to get at acr connection. oh shoot that reminds I need to call scott right now .
 

Last edited by 2009blackpearle; 10-13-2017 at 10:26 AM.
  #8  
Old 10-13-2017, 11:14 AM
jbarr1
jbarr1 is online now
Senior Rider
Join Date: Nov 2015
Location: georgia
Posts: 489
Thanked 51 Times in 48 Posts
Default

A failed ACR will not result in zero compression. Your problem lies deeper if there's zero compression.
 

Last edited by jbarr1; 10-13-2017 at 11:15 AM.
  #9  
Old 10-13-2017, 01:44 PM
rjz500
rjz500 is offline
New Member
Thread Starter
Join Date: Oct 2017
Location: SAN BERNARDINO CA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default ACR Location

The ACR's have a plug for each one under the tank that are easy to get to. Will keep you all posted until I fix this. Thanks everybody for your input.
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
JCleveland
Ironhead
7
01-24-2018 07:36 AM
2014superglide
General Topics/Tech Tips
1
09-21-2017 12:23 PM
Sarah93003
Ignition/Tuner/ECM/Fuel Injection
2
11-01-2015 01:09 PM
mayneman
Shovelhead
21
07-29-2013 08:35 PM


Thread Tools
Search this Thread
Quick Reply: Compression loss


Featured Sponsors
Vendor Directory

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: