docw1
Bill Rankin
I've heard some of the later models used a different sized needle. Otherwise, every year carb should fit every year bike.
Lack of power= carb issue?
- Thread starter ST_SHP
- Start date
- Joined
- Feb 5, 2005
- Messages
- 8,537
- Age
- 77
- Location
- Kingman, Arizona
- Bike
- 2000 ST1100 ABS TCS
- STOC #
- 004
Don't recall the year, but at some point (98?) the cams were made more mild and carbs changed jets 'n needles. It's all documented in the "All Models" service Manual I received with my 01.
Thanks for the corrections folks... I have updated my one overworked memory cell with the needle/cam information.
OP
OP
ST_SHP
Parting a wrecked '91
Thanks for the info. I bought a set of used carbs from a '96 model, so we'll see how it goes with them. I'm going to patch the holes that were drilled in the air cleaner- a lot cheaper than buying a used one.
OP
OP
ST_SHP
Parting a wrecked '91
After a battle getting the air cleaner box replaced on the used set, I got them installed today & it is a night & day difference. Runs MUCH better.
schlep1967
Bill
I knew I had the best suggestion. See post 7. 
Glad you got it worked out!
Glad you got it worked out!
OP
OP
ST_SHP
Parting a wrecked '91
Ding ding ding! You win the prize. Please remit a $2,500 "redemption fee" plus $500 for shipping & handling* to ST_SHP @ BR549!I knew I had the best suggestion. See post 7.
*This will be waived in exchange for a 1982-83 GS1100G with Vetter fairing.
Greetings fellow inmates....been reading all the gr8 posts and seeking info on sketchy petcock diaphram....i'm trying to get a handle on issue my 98 st1100 is having. I replaced the filter(OEM I think) and rebuilt that petcock after leak developed that led me to it last year. Cannot buy that part as far as I know, but i did find the rebuild kit, and after the 2nd effort, got it right and thought i was good to go, after running a few tanks thru it locally.
wrong again..... as i rolled for Denver from Atl, trouble day 2 rolling into Ft. Smith,AR...loss of power at speed on super slab, as I rolled nearly powerless down the exit ramp, it recovered, topped it off at gas station and made it to hotel smooth as silk. next morning I got a few smooth hours up thru Boston mtns in AR before it hit again....took the fuel filter out and it seemed clogged, so poked hole in it with phillips screwdriver, blew thru it and some black grit came out and at that point I could see right thru it(? I know, weird...maybe not stock filter?) so instead of bypassing it with ink pen barrel as planned, I re-installed it and lo and behold, she started up with full choke and running ruff, but eventually smoothed out enough to give me confidence it would run, turned it off and re-assembled bike, fired it up hoping to get to next exit, and she ran so smooth I just kept going....about 2 hrs later, 37 mi south of KC, MO and it did same thing, only this time, i could not get it back so 5 hrs on side of I-49 in this freakin heat wave later, AAA finally shows up and gets me to hotel I had reserved.
My thinking is I have trashed that petcock running w/o filter...i can see fuel in the filter body, but I could not reach the petcock with tools I had on bike, so put it in only shop that would take it
(hub cycle...seems like a good fit), they work on everything and have a ton of honda oem parts in stock, but they have serious backlog, and down a mechanic...could be a while and they may or may not get a handle on it when they do get to it, but it got the bike squared away and allowed me to return to ATL, so now I'm looking to find that kit again(cannot recall where I got it, but will find receipt this week)and get it and 2 honda oem filters delivered there just in case they do not have them in stock+ i want spares now anyway
that petcock/fuel splitter is indeed a weird animal, and reading here about all the other fuel issues, the pressure drop part is something i was not allowing for.....not real clear on exactly ***** is up with that smaller diameter hose on back side of pet cock, but reading here about pressure drop I'm now thinking it plays a very key roll in how that diaphram functions....diaphram has a spring in it and that whole design is just really strange to my eye.....but i got fuel in/out of filter and I know the fuel pump is working and the carbs are starved for fuel, and that petcock is only thing between fuel filter and carb fuel rails...it is my problem, but the problem may be pressure related also with any grit that restricts hose flow.....
anyone run across an after market mod to get that petcock out of the circuit completely? I normally steer clear of mods in lieu of correct repair, but this is clearly a weak point in the design and now that these biles are over 20 years old, running corn fuel, gotta figure that tank is nasty and grit will keep coming out.....will never travel w/o spare fuel filter again, and if I learn of a proven work around for that petcock, i'll do it.
bigger picture here is I may have to get the bike and trailer it to denver honda shop I have history with to get the tank cleaned out and all the lines replaced. Plan was/is to return the bike to Vegas storage where I had it when covid hit and resume using it for winter riding in and around sin city. That ride from denver to Kanab,UT was so mindblowing when i first made the move, I'm planning to take wife over rockies and into kanab to share it with her...assuming I can get the bike back before the snow starts flying, and that's mid-sept at elevation crossing rockies, so looking to do all I can to help insure that happens.
My main bike is ktm 1290 SA-T, so my riding season is not lost but my goal of getting the ST back to Vegas is for sure in question now, dammit. These st1100's are tanks and beyond awesome sport touring bikes, and I truly love traveling on it. added sargent seat, 2" risers on bars, had rear shock rebuilt , wrapped it this past winter(what an ass whipping that was, but worth it) and running pilot roads...it has earned all the love I can give it....it came with staintune pipes(unobtanium now) and i just marvel at it everytime I travel with it...whatever it takes to keep it running, it will get, and right now what it needs is fuel to the carbs.
deeply appreciate and value all the deep knowledge of these very special bikes on this site, beyond happy to support it and hoping a few of you have some specific experience with this petcock issue and can offer advise and links that will help me get mine back on the road faster.
wrong again..... as i rolled for Denver from Atl, trouble day 2 rolling into Ft. Smith,AR...loss of power at speed on super slab, as I rolled nearly powerless down the exit ramp, it recovered, topped it off at gas station and made it to hotel smooth as silk. next morning I got a few smooth hours up thru Boston mtns in AR before it hit again....took the fuel filter out and it seemed clogged, so poked hole in it with phillips screwdriver, blew thru it and some black grit came out and at that point I could see right thru it(? I know, weird...maybe not stock filter?) so instead of bypassing it with ink pen barrel as planned, I re-installed it and lo and behold, she started up with full choke and running ruff, but eventually smoothed out enough to give me confidence it would run, turned it off and re-assembled bike, fired it up hoping to get to next exit, and she ran so smooth I just kept going....about 2 hrs later, 37 mi south of KC, MO and it did same thing, only this time, i could not get it back so 5 hrs on side of I-49 in this freakin heat wave later, AAA finally shows up and gets me to hotel I had reserved.
My thinking is I have trashed that petcock running w/o filter...i can see fuel in the filter body, but I could not reach the petcock with tools I had on bike, so put it in only shop that would take it
(hub cycle...seems like a good fit), they work on everything and have a ton of honda oem parts in stock, but they have serious backlog, and down a mechanic...could be a while and they may or may not get a handle on it when they do get to it, but it got the bike squared away and allowed me to return to ATL, so now I'm looking to find that kit again(cannot recall where I got it, but will find receipt this week)and get it and 2 honda oem filters delivered there just in case they do not have them in stock+ i want spares now anyway
that petcock/fuel splitter is indeed a weird animal, and reading here about all the other fuel issues, the pressure drop part is something i was not allowing for.....not real clear on exactly ***** is up with that smaller diameter hose on back side of pet cock, but reading here about pressure drop I'm now thinking it plays a very key roll in how that diaphram functions....diaphram has a spring in it and that whole design is just really strange to my eye.....but i got fuel in/out of filter and I know the fuel pump is working and the carbs are starved for fuel, and that petcock is only thing between fuel filter and carb fuel rails...it is my problem, but the problem may be pressure related also with any grit that restricts hose flow.....
anyone run across an after market mod to get that petcock out of the circuit completely? I normally steer clear of mods in lieu of correct repair, but this is clearly a weak point in the design and now that these biles are over 20 years old, running corn fuel, gotta figure that tank is nasty and grit will keep coming out.....will never travel w/o spare fuel filter again, and if I learn of a proven work around for that petcock, i'll do it.
bigger picture here is I may have to get the bike and trailer it to denver honda shop I have history with to get the tank cleaned out and all the lines replaced. Plan was/is to return the bike to Vegas storage where I had it when covid hit and resume using it for winter riding in and around sin city. That ride from denver to Kanab,UT was so mindblowing when i first made the move, I'm planning to take wife over rockies and into kanab to share it with her...assuming I can get the bike back before the snow starts flying, and that's mid-sept at elevation crossing rockies, so looking to do all I can to help insure that happens.
My main bike is ktm 1290 SA-T, so my riding season is not lost but my goal of getting the ST back to Vegas is for sure in question now, dammit. These st1100's are tanks and beyond awesome sport touring bikes, and I truly love traveling on it. added sargent seat, 2" risers on bars, had rear shock rebuilt , wrapped it this past winter(what an ass whipping that was, but worth it) and running pilot roads...it has earned all the love I can give it....it came with staintune pipes(unobtanium now) and i just marvel at it everytime I travel with it...whatever it takes to keep it running, it will get, and right now what it needs is fuel to the carbs.
deeply appreciate and value all the deep knowledge of these very special bikes on this site, beyond happy to support it and hoping a few of you have some specific experience with this petcock issue and can offer advise and links that will help me get mine back on the road faster.
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ST1100 - How to do an emergency bypass of the fuel valve
ST1100 - How to do an emergency bypass of the fuel valve
Some comments you made have me interested. Around 2+ hours of highway driving and you have the problem? Sounds like....if bypassing the vacuum valve doesn't work....you may need to consider inspecting your fuel pump, hoses and the bottom insides of the tank as well.
Andrew Shadow
Site Supporter
Here is the link to the article referenced above by Oldbikefixer.
ST1100 - How to do an emergency bypass of the fuel valve
Cheap and easy to do at least for diagnostic purposes. Many people bypass the fuel valve permanently- your choice.
F.Y.I. There have been many reports of the after-market fuel valve overhaul kits not working very well or for very long before the diaphragm tears again. Many have reported that the diaphram is slightly smaller in size than the original Honda one and must be stretched to much to install it, leading to premature failure. Doing the simple bypass as a diagnostic measure will tell you if it is damaged again. I have no information about any of the after-market kits in particular.
ST1100 - How to do an emergency bypass of the fuel valve
Cheap and easy to do at least for diagnostic purposes. Many people bypass the fuel valve permanently- your choice.
F.Y.I. There have been many reports of the after-market fuel valve overhaul kits not working very well or for very long before the diaphragm tears again. Many have reported that the diaphram is slightly smaller in size than the original Honda one and must be stretched to much to install it, leading to premature failure. Doing the simple bypass as a diagnostic measure will tell you if it is damaged again. I have no information about any of the after-market kits in particular.
Thx for the feedback OBF & Andrew. After I posted, I actually found a brand new petcock for sale on ebay and ordered it, along with rebuild kit for one currently installed on my ST, and 2 OEM filters. I rode this bike all over the rockies and down to Vegas for 2 years with no fuel flow issues at all. Bike sat in storage for a year in Denver and another year in Vegas (serious heat inside storage shed expanded and ruined my LiOn jump starter during that time). It was leaking oil and fuel as I rode it home to ATL for maintenance, but it never, not once, failed to start or lost power. I gotta suspect that the fuel filter I installed was not OEM and led to this failure. I also noticed, after i finally got the rebuild kit installed properly into petcock, that the starting was instantly easier, so thinking there was an issue all along with the petcock. Will post here once i get it resolved and hopefully trouble free over to Denver, then down to Vegas......depending on how new fuel filter holds up, I'll have the tank cleaned and treated if it fails. Bought an 82 yamaha turbo new in 84 that had not sold and sat 2 years...it developed same issue but was under warranty and they treated the tank to resolve the issue.....grit just has to be in these 20+ year old tanks, so traveling with spare fuel filter is way to go.....thx again for feedback and Happy Trails!
I rebuilt the vac valve right after I got the bike, Autumn of 2014. Checked it during a refurbishment, October 2021, looking for fuel leaks. During the refurb, I found the kid diaphragm had a small split but not leaking fuel. Rebuilt it again. In the first kit's favor, it did last 7 years. But....the original had been still functional, 1991-2014, rebuilt it as a precaution since original diaphragm did seem very floppy and loose, maybe stretching out?