Well, I guess that explains the loss of power...

Joined
Apr 8, 2012
Messages
1
Location
Minneapolis, MN
Bike
ST1100
Background

The ST died on me the other night while on the freeway. Had high RPMs, and suddenly lost power. Coasted to the shoulder, and eventually managed to get her started back up. Limped home by keeping the needle under 55 mph. (I noticed the power starting to go if I attempted to accelerate, so I obeyed all traffic laws.)

I was convinced my shoddy "winterizing" had gummed the carbs, but I ended up talking to a mechanic who told me it sounded like a fuel line issue. Ended up buying a new fuel filter, since that seemed like a cheap start for diagnosis. Also, why not, right? The old one had over 5 years on it...

The fix is in

Ended up finding a couple posts from other riders here with the same issue, and found the bypass workaround. I completed the bypass, and pulled the whole petcock out of there. I took the bike for a spin, and it seems to be working great! Decided to pull the petcock apart after I got back home, and think I figured out the cause of the problem...
20170416_174500.jpg

That's bad, right? :rolleyes:

Looks like I have a diaphragm replacement in my future...
(Unless enough people here who have never replaced theirs after the bypass convince me I don't need to!)
 

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
As many others have done, we just remove the cutoff and leave it removed. The choice is yours but I've got thousands of miles without one and no problems.
+1, just remove it.
 

craigstys

STOC #8621 Now on my 2nd ST1100
Joined
Jun 27, 2012
Messages
41
Age
62
Location
Madison, WI USA
Bike
1999 ST1100X
STOC #
8621
This same thing just happened to me on my '99 ST1100. I would lose power and die out at about a half tank. Would take a few minutes to get it going again. I bypassed it. Took apart the old valve and looked exactly like the one pictured. Runs terrific now. My previous bike was a 1991 ST1100 that had the bypass already done when I bought it.
 

Ron

Joined
Feb 5, 2005
Messages
1,665
Location
Orlando
Bike
ST1100s
STOC #
2432
I left mine about 40 feet off the south side of east I-40 (out west) about 15 years ago. No problems for me yet.

You did plug the vacuum line, right?


I've owned several 1100s over the years and the first time I'm working in that area, it goes. I do it as a pro-active move.
 
Last edited:

craigstys

STOC #8621 Now on my 2nd ST1100
Joined
Jun 27, 2012
Messages
41
Age
62
Location
Madison, WI USA
Bike
1999 ST1100X
STOC #
8621
I found a perfect sized screw in the garage to plug the vac line and even zip tied it to the frame when done. My previous bike had it done correctly as well. Easier than changing the oil.
 

Ron

Joined
Feb 5, 2005
Messages
1,665
Location
Orlando
Bike
ST1100s
STOC #
2432
I found a perfect sized screw in the garage to plug the vac line and even zip tied it to the frame when done. My previous bike had it done correctly as well. Easier than changing the oil.
I found one of the mounting screws works perfect to plug the line. I just screw it into the end of the hose.
 

ST1100Y

Site Supporter
Joined
Dec 4, 2012
Messages
4,981
Age
59
Location
Vienna, AuSTria
Bike
ST1100Y, ST1100R
STOC #
637
When inspected on regular base you'll find and fix a tiny tear long before it's causing an actual issue...


Img_1789 6x45.jpg


Don't forget to check the carb-sync afterwards; the leak might have existed for some time and the flaps be offset to compensate...

I rebuild and keep the auto fuel valve in my ST's for it's intended safety function.
 

ChriSTian_64

Site Supporter
Joined
Feb 5, 2020
Messages
862
Age
59
Location
Deux-Montagnes, Quebec, Canada
Bike
2000 ST1100Y
STOC #
9063
I rebuild and keep the auto fuel valve in my ST's for it's intended safety function.
Well, that is also my thinking.

Like any other things that needs an inspection and possibly a replacement once on a while, there is nothing complicated in just replacing the diaphragm and be good to go for another few years or decade.

As you say, it is a safety device. Sure you could run without it. You could also fix it and keep it.
I ordered a new replacement kit on ebay, for about 18 CAD or $ 14 US.

It's good to know how to bypass it though. If I'm ever stuck somewhere, I know what are the symptoms, and I know that I can fix it and how to do it, as a temporary fix.

I understand that we could consider the fuel cutoff valve as a possible threat, a possible ennemy, a show stopper, and so, for peace of mind, we want to eliminate the risk and just take it out.
Maybe we could also consider it as a possible friend, and a possible life saver.
 
Last edited:

Bee

Joined
Aug 21, 2021
Messages
114
Age
54
Location
Lincolnshire England
Bike
2002 Blue ST1100
Just curious, looks like you can buy diaphragm rebuild kits fairly easily and cheaply. Is there a reason why you don’t just replace the diaphragm? Some vendors list the ST1100 kit as the same on the GW1500 model but it seems the GW one is much cheaper, are they the same parts? Does anyone know for sure?
 
Joined
Oct 9, 2012
Messages
81
Location
Singapore
Bike
ST1100Y
Just curious, looks like you can buy diaphragm rebuild kits fairly easily and cheaply. Is there a reason why you don’t just replace the diaphragm? Some vendors list the ST1100 kit as the same on the GW1500 model but it seems the GW one is much cheaper, are they the same parts? Does anyone know for sure?
I vaguely rem many moons ago(maybe 10-11yrs) when my petcock failed, went to the local honda parts dealer, no ST11 petcock available but they did sell me GL1500 petcock. The parts guy said it was the same thing.
The petcock looks exactly the same except the mounting brackets are different(I think GL1500 has a different mounting location), so I had to swap the mounting bracket from old to new unit.

Since then I've bought a rebuilt kit and rebuilt another for standby over the years :):)
 

Bee

Joined
Aug 21, 2021
Messages
114
Age
54
Location
Lincolnshire England
Bike
2002 Blue ST1100
Great, thank you. That confirms what I have been told by a vendor. They are the same. I have just ordered the kit.
 
Top Bottom