Vacuum Leak - Harley Davidson Forums

Go Back   Harley Davidson Forums > Harley Davidson Motorcycles > Sportster Models
Log In 

Sportster Models 883, 883 Custom, 1200 Custom, 883L, 1200L, 1200S, 1200 Roadster, XR1200, and the Nightster.
Sponsored by: Rush Racing Products

Vacuum Leak

Thread Tools Search this Thread
Old 09-24-2008, 05:14 PM
Sundog's Avatar
Sundog Sundog is offline
One Of The Regulars
Join Date: Jan 2008
Location: The Suncoast (FLA)
Posts: 213
Default Vacuum Leak


I believe I have a vacuum leak on my '99.

I replaced all the tubing from the carb to the EOS and the petcock, (all dry and cracked and somebody taped it) but the idle still likes to go high and hang there. Still poofs occasionally when coming in for a landing too.

Where else could it be leaking? I don't really want to hose it down with WD-40.

Or what else could manifest itself with those symptoms.

Still getting acquainted with (her/him) it. The Lady in Red. No, she won't do windows but she looks goooood.


'99-1200S Who needs Chrome?
Reply With Quote
Old 09-24-2008, 07:34 PM
Zimbob's Avatar
Zimbob Zimbob is offline
Outstanding HDF Member
Join Date: Dec 2006
Location: Grottoes Va.
Posts: 2,883

carb gasket?
If you choke a Smurf, what color does he turn ?

2012 Road King - "Pearl"
2007 Road King Classic - Totaled
2002 sportster 883R/1200 - traded
1985 Honda VF700S - wore slam out
1969 Triumph TR6R - wore slam out
Reply With Quote
Old 09-24-2008, 08:15 PM
Doug45601 Doug45601 is offline
Road Master
Join Date: Sep 2007
Posts: 976

Mine (also a 99) acted up that way and I found it to be the rubber bladder had worn out in the carb. Actually had a small torn place in it allowing the carb to suck in air.
Time is a waste'n Lets Ride!

Retired, US Navy 30+
and I miss it!
Reply With Quote
Old 09-24-2008, 08:59 PM
JosephGarcia JosephGarcia is offline
Outstanding HDF Member
Join Date: Aug 2007
Location: fegfsg
Posts: 2,225

check the diaphragm in the carb and replace your intake manifold seals and the carb to intake seal. the intake to cylinder head seals dont last too long becuase of the design.
Reply With Quote
Old 09-24-2008, 11:01 PM
Just Dave's Avatar
Just Dave Just Dave is offline
Ultimate HDF Member
Join Date: Mar 2008
Location: Spring Hill, Fl
Posts: 6,573!/profile.php?id=100000916551016

+1 on what Joseph said also while you are in the carb go ahead a replace the diaphragm in the accelerator pump, Thats where that little rod goes into the top of the float bowl.

Scars are like Tattoos with way better Stories.
Reply With Quote
Old 09-25-2008, 01:04 PM
Sundog's Avatar
Sundog Sundog is offline
One Of The Regulars
Join Date: Jan 2008
Location: The Suncoast (FLA)
Posts: 213

Thanks to all for the input.

I will go ahead and tear the carb off. I've wanted to see what other hacker mods it's previous owner made. I suspect it has larger jets and maybe the needle has been jacked-up.

I do agree that the rubber parts don't last forever, so I'm certain the advice is all good. I may do the diaphragm in the petcock while I'm at it.

The VOS.. is that mearly a set of switch contacts that open or close when vaccum is applied? Can it be checked with a VOM?

Thanks again for all the help.

'99-1200S Who needs Chrome?
Reply With Quote
Old 09-25-2008, 01:38 PM
EVO80's Avatar
EVO80 EVO80 is offline
Road Captain
Join Date: Jun 2007
Location: S.C.
Posts: 530

You can check your VOES switch with a Ohm meter and vacuum pump.You need the vacuum pump to create the vacuum of 3.5 to 4.5 inches. The ohm meter should read zero when the vacuum is between these settings. If a higher (than 4.5 inches) or lower (less than 3.5 inches) value is required to to close the switch (zero reading) the switch needs replacing. You may also only need to replace the VOES hose, I believe HD sells this separately, as it may be cracked or worn out.


2007 Streetbob
<a href= target=_blank></a>
Reply With Quote

Similar Threads
Thread Thread Starter Forum Replies Last Post
Spark Plugs RodeoHard Evo Classic Models 19 04-13-2011 08:00 AM
rear cylinder sucking in all the time jimkeating Exhaust System Topics 10 07-13-2010 12:25 PM
Bummer! 1Coastie General Harley Davidson Chat 30 03-05-2009 09:16 AM

1985, 2002, 883cc, check, davidson, fix, harley, idles, king, leak, problem, road, sportster, switch, vacume, vacuum, voes, xl

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

All times are GMT -5. The time now is 01:14 AM.