Groaning ST1100 and some odd electrical stuff

Joined
Oct 24, 2016
Messages
6
Location
Seattle
Bike
1991 ST1100
Last night when I got home, I got off the bike and heard a noise. I looked around, and didn't see any lions or tigers lying in wait, so I took off my helmet, and heard the noise again.

About every 15 seconds or so, there would be this groaning noise coming from my 1990 ST1100 that would last for a couple of seconds.

I figured "fuel pump", so I took off the seat, but... the sound wasn't coming from there.

Moving around the bike I determined it to be coming from above the right footpeg, about ankle height. (Behind much plastic and metal, which is just dark magic to me so far, on this new-to-me bike.)

I turned the bike back on. No problem.

I tried the throttle, clutch, brakes. No problems.

But the groaning continued when I turned the bike off.

So I parked it outside in the driveway, away from the house and other flammable objects, and ... ignored it.

Today, searching the forums, I see people saying that this is common, and is the fuel pressure normalizing, buuuuut... the sound happened every 15 seconds for ten minutes or so... it was unaffected by turning the bike back on and off... so it seems to me that "fuel pressurization" doesn't quite fit the symptoms I would expect.

I'm looking for other ideas, and - honestly - whether I should be worried or not? What is at ankle height on the right side of the bike that could emit groaning noises on a consistent basis for 10-15 minutes or more after the bike was turned off?

Meanwhile, in weirdo electrical stuff land...

I have noticed that even bumping the cutoff switch will cause the bike to die, so there's a loose wire in there somewhere. I also see the plastic cover the cutoff switch is mounted on is discolored and worn. The left one (lights, choke) is "normal" colored, but the right one has faded to light grey. Should I just replace the whole thing, or pull it apart and mess with the loose connection in the cutoff switch?

And, while riding home last night in the dark, I flipped on the high beams a couple of times in particularly dark sections of road. One time, when I turned off the high beam, the low beam failed to come on again, and I had no headlight! Flipping the switch a couple of times eventually got the main headlight to turn on, but I am wondering if this failure is indicative of a headlight problem, wiring problem, or...?

What are your thoughts?

And THANK YOU!!


I am completely in love with my ST and cannot wait for my new custom-made Clearview Shields windscreen to be ready!!
 

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
The groaning is caused by "heat soak" when the bike is shut off. There's no longer any air or coolant circulating when you stop a fully warmed engine so temps actually increase slightly before decreasing. This has the effect of heating the fuel in the tank slightly forcing the relief valve in the cap to open. The little check valve in there vibrates creating the noise. Next time you hear it loosen the gas cap momentarily as a test, that will cause it to immediately stop. They all do it and it's completely normal.

Regarding the kill switch sensitivity, rather than a loose wire I suspect dirty contacts in the switch. Do you're best to blast some contact cleaner into the switch assembly. While you're at it do the starter & Hi/Lo beam switches too.
 
Joined
Mar 20, 2016
Messages
1,201
Location
Auckland, New Zealand
Bike
2005 ST1300
STOC #
8901
The groaning sound when the bike is parked is completely normal for my bike as well. If you pull the fuel cap off and remove the vent hose, you can blow and suck on the tube and recreate the sound.

You headlight problem just sounds like a dirty switch. I pulled my indicator switch apart recently for some love for the same sort of reason. Get in there with some contact cleaner and work the switch around a bit to clean the contacts. Your kill switch is probably the same with dirty contacts that don't take much movement to stop current flow.

The fact that the right switch pod is faded but the left one is not tells me the left one has probably been replaced, and the right is original. Rubbing vaseline into the old one will restore some of it's original appearance.

If the bike is new to you, it might pay to spend some time removing the bodywork and going over all the connectors with contact cleaner, then a little dielectric grease. I had some corrosion in the connectors right behind the steering head that caused a misfire until corrected. You need to pull the fake tank off, then the airbox, for easy access.
 
Joined
Mar 13, 2012
Messages
5,046
Location
soCal
Bike
'97 ST1100
STOC #
687
the sound happened every 15 seconds for ten minutes or so... it was unaffected by turning the bike back on and off... so it seems to me that "fuel pressurization" doesn't quite fit the symptoms I would expect.
As others have said, its normal. I suspect the pattern you observed has to do with this:

1. heat from the engine warms the tank enough to increase internal air/fuel vapor pressure to the point where it exceeds the pressure relief valve limit and expels the air, making the sound.
2. the engine is still just as hot as it was 15 seconds ago, so repeat step 1 again.
3. the cycle repeats itself until the engine has cooled to the point it can no longer increase the tank vapor pressure beyond the pressure relief valve limit.
 
Joined
Sep 10, 2011
Messages
2,211
Location
West Michigan
Bike
'98 ST1100
STOC #
8470
Could be normal as described above, but it also may be a mouse or two farting. Put some traps out and see if you can catch a mouse, or two, if it sounded a little like a symphony .
 

paulcb

- - - Tetelestai - - - R.I.P. - 2022/05/26
Rest In Peace
Joined
Jun 4, 2013
Messages
4,652
Location
Celina, TX
Bike
'97/'01 ST1100 ABSII
STOC #
8735
Could be normal as described above, but it also may be a mouse or two farting. Put some traps out and see if you can catch a mouse, or two, if it sounded a little like a symphony .
Surely you're joking?
 
Joined
Sep 10, 2011
Messages
2,211
Location
West Michigan
Bike
'98 ST1100
STOC #
8470
Surely you're joking?
Please don't call me Surely.

After I heard that noise, I put out a trap and the next day there was a mouse in it - QED. And I didn't hear the noise after I caught the mouse.

BTW, I also discovered the small vent hose from the gas cap was being pinched by the clamp on the side of the gas tank. I removed the OEM screw and replaced it with a longer screw and self-locking nut so the hose was secured but not pinched - check your hose for pinching.

The gas cap has a two-way relief valve. You may want to squirt some carb cleaner into the small fitting in the gas cap to clean out any debris. BTW, it takes quite a bit of pressure ( attach a length of small tubing to the fitting and blow & suck on the tubing to check the relief valve ) to get the relief valve to work. You may hear a sound like a mouse farting, but it's the relief valve opening, so don't confuse the sound from the sound of a flatulant mouse.

Also make sure the distal end of the vent hose isn't plugged with debris.

If the relief valve and hose seems OK, then you better for sure put a few traps out.
 
Last edited:

paulcb

- - - Tetelestai - - - R.I.P. - 2022/05/26
Rest In Peace
Joined
Jun 4, 2013
Messages
4,652
Location
Celina, TX
Bike
'97/'01 ST1100 ABSII
STOC #
8735
Please don't call me Surely.

After I heard that noise, I put out a trap and the next day there was a mouse in it - QED. And I didn't hear the noise after I caught the mouse.
OK, I'll not bite on this 'fool's errand' anymore... ;)
 

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
I prefer to think of the noise as my bike whining in disappointment because we stopped riding....
 
Joined
Sep 10, 2011
Messages
2,211
Location
West Michigan
Bike
'98 ST1100
STOC #
8470
I understand the mice in Texas are much bigger than the mice here in Michigan, too.

But seriously ( seriously ) , I wish the vent in the gas cap would relieve the pressure sooner. It takes a bit of pressure/vacuum to open it. Sometimes when filling up, when I remove the gas cap , it seems like there is a lot of vacuum.

I wonder if there is a specification on how much pressure/vacuum it should take ?
 
Last edited:

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
I don't think there's ever a vacuum in there unless the vent has malfunctioned or plugged up. A vacuum in the tank would cause fuel starvation to the engine. What you hear upon opening the cap is pressure relief. There is no doubt an opening pressure specification for that relief valve as purchased by Honda.
 

kiltman

Site Supporter
Joined
Apr 27, 2013
Messages
3,280
Age
68
Location
Stratford, Ontario Canada
Bike
2002,ST1100ABS
STOC #
8826
I understand the mice in Texas are much bigger than the mice here in Michigan, too.

But seriously ( seriously ) , I wish the vent in the gas cap would relieve the pressure sooner. It takes a bit of pressure/vacuum to open it. Sometimes when filling up, when I remove the gas cap , it seems like there is a lot of vacuum.

I wonder if there is a specification on how much pressure/vacuum it should take ?
Don't know the pressure value, however, if you smear some grease under the rubber ring of the gas cap and under the metal ring in the fuel tank filler neck it will make it easier to remove the cap.
 
OP
OP
boomba
Joined
Oct 24, 2016
Messages
6
Location
Seattle
Bike
1991 ST1100
Thanks everyone for all the input! This has all been super helpful, and when it gets above freezing again, I'll step back outside with a screwdriver and do some electrical contact cleaning.

In other news, I received and installed my new Clearview windshield, which is slightly taller and wider than the original. Again, when the ice melts, I'll take it out for a spin (har har) and do a review of the shield. It looks fabulous.

Much thanks to all!
 
Joined
Aug 26, 2013
Messages
115
Location
Dewitt, Michigan
Bike
1997 ST1100
Just don't use compressed air to blow out or clean out the gas cap. There's a little rubber valve in there and you could blow it right out of it's seat. (don't ask how I know that). Replacement gas caps are not cheap. I had to un-crimp and disassemble the cap to get it all back together. Works normally now and i get the gas tank farts after a long ride. It's just the cap, doing what it does.
 
Joined
Jun 3, 2006
Messages
3,512
Location
British Columbia
Bike
2021 RE Meteor 350
Don't know the pressure value, however, if you smear some grease under the rubber ring of the gas cap and under the metal ring in the fuel tank filler neck it will make it easier to remove the cap.
I haven't found it necessary to put any grease "under the metal ring in the fuel tank filler neck", only under the rubber gasket in the cap. It is the gasket that sticks to the filler neck, so grease, a very light smear only under the gasket, allows the cap to slide over the stuck gasket.
 
Joined
Jan 30, 2016
Messages
95
Location
Kansas City , KS
Bike
ST1100Y
STOC #
8892
I've run into switch issues on several occasions. The headlight not working was also one of the gremlins that had to get resolved when mine got rescued after being left outdoors in the weather for a few years. The switches are all about the same on metric bikes. There's contact points, springs, detent balls, and old nasty grease that's gummed up and has gotten hard. Good news is, with a little patience and attention to detail, you can take them apart, clean em up, and put some 'modern' dialectic grease on the contacts.

I thought about replacing the switches, but being a cheap arse I just took them apart. It fixed all my issues including a no headlight issue, and was super easy to do. Hope it helps...

Frank
 
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