Rubber Fuel Hoses - did I get them all?

tbloor

tbloor

Joined
Feb 5, 2026
Messages
6
Age
36
Location
Paris
Bike
ST1100
Hi guys,

I just wanted to say this place is awesome. It’s already saved me several headaches regarding the fuel valve on my "new-to-me" 1999 ST1100 ABS (150,000km).

The Haynes manual suggested replacing the fuel hoses, so while I had the fuel valve off, I decided to go for it. I've replaced the lines from the tank to the filter, and from the filter to the plastic connector at the back of the carb block and then the pair of hoses that run into the metal inlets.

Getting into that center-bottom area behind the carbs was a total pain in the arse. I had to pull the tank to work the new hoses into the intakes. After a fair bit of swearing, I managed to get a jubilee clip on the left and a modern fuel injection screw-clamp on the right.

My questions for the experts:

  • Is that "it" for the critical rubber? Haynes says to replace the hoses, but I want to be sure I'm not missing any hidden rubber bits.
  • The Carb Block: I know there are plastic/aluminum lines inside the carb bank itself, but I’m assuming the main rubber lines I just replaced are the primary culprits for age-related failure?
  • The "Red Line" Hoses: The ones I pulled had the red stripes down the side, which I assume means they were the 25-year-old originals from the Honda factory. They were fairly stiff.
I’m itching to put it back together and finally enjoy it. If anyone can confirm I’ve hit the main targets and put my anxiety to bed, I’d really appreciate it!
 
So I’ve opted not to take the carbs off, as it is a level of complication for another day. I’ve just replaced all of the rubber fuel hoses running into the back of the carbs.
 
Does the 1100 have the infamous 5-way Tee under the carbs like 1300's (under the latter bike's throttle bodies)? If so, you might consider raising said Tee so that it is above the carbs for easier future service. This has been suggested in the past and is accomplished by replacing the rubber hoses using longer pieces. Obviously, if the 1100 does not have this troublesome fitting, you have dodged a bullet.
 
When I bought my 1998 ST 1100 (90.000 km) 4 years ago, I went through the same process.
I had ridden modern motorcycles before (BMW R1200 GSA, R 850 GS, K 1200 GT, K 100/2, K 75 S, Honda CB 750).
In 2016 I bought an RV (camping car in French) and fitted a Honda Sh300 on a trailer.
That meant I rode a lot less, so I sold my 1200 GSA and looked for a relatively cheap, reliable bike (with few electronics) that I could service myself.
This bike would have to last till the end of my riding career (age 61 now). A lot of reading and researching lead to the purchase of an ST 1100.

During the winter of 2022, I stripped the motorcyle in a heated garage and checked almost everything.
I'm no mechanic, but during my riding years I have picked up some things.
With the help of the Honda and Haynes manual, combined with multiple Youtube fragments, it took me about 2 months (mostly during weekends).
Sometimes I had to order parts, so it took longer than expected, but I was in no rush.

- replaced distribution belt, spanner and tensioner
- replaced elbows (and O-rings), all hoses in the cooling system, thermostat, and radiator cap
- replaced 4 carburetor inlet rubbers
- replace all fluids, filters, and spark plugs, checked and synchronized valves
- cleaned all brake calipers, fit speed bleeders and replaced brake and clutch fluid
- applied new grease to rear wheel drive shaft and replaced rear wheel torsion dampers
- cleaned and lubricated speed cable at front wheel axle + lubricate throttle cables and choke cable
- cleaned and greased shifting mechanism, main stand and side stand.
- replaced fork oil (slightly thicker) and fork seals, polished inner legs and fitted accordion rubbers.
- replaced (still OEM) rear shock with an almost new Wilbers.
- fitted handlebar risers and adjustable clutch lever (from a VFR 750).
- cleaned and applied dielectric grease to all electrical connections.
- converted most bulbs to LED.
- checked known weak points (headset, swing arm, starter relay, etc.)

Since than I have ridden 15.000 km without problems, which doesn't mean nothing can go wrong (it is still 27 years old).

So, you should take the carbs off and replace all coolant hoses and the tube that runs to the coolant overflow tank (rear right).
Coolant hoses ST 1100
Check the inlet rubbers of the carbs and replace if necessary. Note that you will propably not be able to mount the carbs at the first attempt :sneaky:.
Check/replace the aluminium elbows (these are famous for cracking/leaking) and get new O-rings.
Depending on your budget and mechanical abilities, you can use my list as a guide line.
 
None of the fuel hoses have been a problem on the 4 st1100's that I've had. I did have a coolant hose under the carbs go bad on one of them at about 115,000 miles on a bike that was stored outside before I owned it.

It sounds like this project started as a fuel valve repair and you went a little further and replaced all the fuel lines while there. If you don't plan to remove the carbs and do the water hoses which is a fairly large task, you may want to put the bike back together and enjoy it for now.

Does the bike run well?

I've had 4 of these bikes and 2 of them I bought as projects. Dirty Carbs have been the biggest issue I've seen with bikes that have set a long time.
 
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So, whilst we are talking about carbs off... I had work done on the coolant system after a catastrophic leak back in 1998 whilst I was at a sidecar rally here in the UK, ended up being trucked home. Anyway, after that it went into my trusty dealer (now out of business 😭) who fixed it up. Looking at the invoice they replaced hoses and the seals under the elbows and fitted new carb to engine rubbers. However, a couple of weeks ago, whilst preparing to go to another sidecar meet, I got the dreaded leak from the back of the engine and on a really cold (for the UK) day I had steam rising from under the false tank cover.

I am really struggling to find someone to get in there and find out what has gone wrong, so I am contemplating going in myself!

As those who have read my previous posts, I am no mechanic, so my question is... how difficult a job is this?
 
How hard is relative to ones Mechanical Skills, for me it was pretty easy replacing the hoses under the carbs. First question do you have a good place to work on the bike, do you have the right tools? Half the job is taking off the Tupperware, JIS screwdriver set is a must have, ( or use the screwdriver in the Honda tool kits) and one more hint take a picture or video of your bike as you take pieces off so you will now where the go when it's time to put it back together.
 
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