Pull the tank off and the hoses will be staring you right in the face.
You can get the vacuum line at NAPA, 6mm would be my preference.
Take an old hose as a sample and say match it up, please!
When you put them back on, the nipple on the far left on the IACV does not have a hole in it.

 

Thank you! I stumbled upon a photo and some text about where these critters are located after a lot of dead ended searches leading me to all sorts of "plumbing". I ordered 3mm ID silicone hose as recommended on that webpage, but if that's too small I'll follow your lead and take a sample to my local auto supply shop.

 

I prefer silicone hose material. Handles the heat from the engine.

 

I think I wound up with this on this on a couple of bikes

https://www.napaonline.com/en/p/NBHH461

and then this on the others

Amazon.com: XINLIYA Silicone Vacuum Tubing Hose Line, 10 Ft 1/4" (6mm) Inner Diameter Hose, High Tempterature 130PSI Max Pressure for Multiple Use, Auto Replacement Vacuum Hose Line for Vehicle Radiator (Black) : Automotive

Buy XINLIYA Silicone Vacuum Tubing Hose Line, 10 Ft 1/4" (6mm) Inner Diameter Hose, High Tempterature 130PSI Max Pressure for Multiple Use, Auto Replacement Vacuum Hose Line for Vehicle Radiator (Black): Vacuum - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Both worked okay. I think I ran out and did a quick trip to NAPA, the guy laughed when I said give me 10'. I use them for the mercury gauges as well.

 

I think I wound up with this on this on a couple of bikes

http://[URL]https://www.napaonline.com/en/p/NBHH461

[/URL]
and then this on the others

http://[URL]https://www.amazon.com/...=6mm+silicone+line&qid=1708033417&sprefix=6mm+silicone+line,aps,216&sr=8-8&th=1

[/URL]

Both worked okay. I think I ran out and did a quick trip to NAPA, the guy laughed when I said give me 10'. I use them for the mercury gauges as well.

I think I wound up with this on this on a couple of bikes

https://www.napaonline.com/en/p/NBHH461

and then this on the others

Amazon.com: XINLIYA Silicone Vacuum Tubing Hose Line, 10 Ft 1/4" (6mm) Inner Diameter Hose, High Tempterature 130PSI Max Pressure for Multiple Use, Auto Replacement Vacuum Hose Line for Vehicle Radiator (Black) : Automotive

Buy XINLIYA Silicone Vacuum Tubing Hose Line, 10 Ft 1/4" (6mm) Inner Diameter Hose, High Tempterature 130PSI Max Pressure for Multiple Use, Auto Replacement Vacuum Hose Line for Vehicle Radiator (Black): Vacuum - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Both worked okay. I think I ran out and did a quick trip to NAPA, the guy laughed when I said give me 10'. I use them for the mercury gauges as well.

Do I need hose clamps or is friction fit good enough? (I'm amazed that my OEM hoses have lasted this long).

 

No clamps required.
The 1050s have a T for the lines and they can stand a little blob of Hylomar on the barb to glue it in place.
Otherwise, you put the tank on and wonder what it runs so poorly. How do I know that one...

 

For the ECU side of the vacuum line, the 6mm needs a reducer to bring down the size. Once you take the hose off the ECU side (just under the seat) it will make sense. I’m sure it was explained in a forum post.

 

Use more of the hose than the original corrugated vinyl pieces when you replace them - avoid kinking them.

 

Just got 6mm & 3mm silicone hose delivered. My garage is not heated, going to pull the tank and wait a few days for warmer, sunny weather before changing hoses. I have to take a look at my ecu because I don't recall a vacuum line to it.

 

There should be one running up to the airbox.
I think it's purpose is to create online discussions about whether or not it actually does anything.

 

My ecu is "1000, mod B" and is shaped differently from others I have seen online. I'm certainly going to locate the hose and replace it when I find it.

 

The corrugated line between the airbox and ECU was deleted at some point at the factory. If you don't have it just make sure there's no open holes into your airbox other than the main one air is supposed to go through.

 

 

View attachment 832116

New development boys & girls: I pull the tank & airbox and look at my vacuum hoses. They are confirgured very differently than what photos & videos illustrate. My corrugated lines are in good condition, but they run under the throttle bodies and attach to a 9mm OD nipple at the rear of the bodies. (Look at the photo) There is a small hard rubber collar that fits over the hose and slides onto the throttle body. (You can see the cracked remnants) The 6mm rubber collar that fits the stepper is fine, so I'm going to buy some 9mm ID hose, make a new coupling to fit, and hopefully put everything back together.

 

 

The 6mm Silicone hose fit on 03 Sprint ST (and others). Don't even need zip ties on them.

 

Vacuum line to ECU - 03 Sprint ST

 

Napier, it's not the corrugated hoses that are the problem, it's the rubber 'boots' at the ends. Just replace the whole mess with 6MM hose.

 

6mm hose will not fit on the throttle bodies on my ST. Scroll back a few posts to view the 9mm nipples on my bike and the 9mm rubber boots that were used to connect them. My hoses run under the throttle bodies and up to the nipples. Note that my throttle bodies are configured differently that most of the images posted online where the nipples are located on the forward side. Mine face the rear of the bike. I have 9mm hose on order. I'll make new boots and plug 'em in just like they came from the factory.

 

Vacuum line to ECU - 03 Sprint ST
View attachment 832127
View attachment 832129

Vacuum line to ECU - 03 Sprint ST
View attachment 832127
View attachment 832129

Thanks for the photos. Yes, my vacuum line is present on the ECU, but covered by the OBD2 cable running over the top of it. It's well connected, so I'm not going to touch it.

 

The 6mm do fit. Just gotta twist them on

 

Sorry, but 6mm ain't gonna fit on a 9mm nipple. Ask me how I know.

 

https://www.triumphrat.net/threads/sprint-rs-01-throttle-idle-low-rev-choppiness-problems.973293/post-2004112615

Here's an photo of 6mm silicon hose on Stepper and Throttle body. (from above thread).

 

https://www.triumphrat.net/threads/sprint-rs-01-throttle-idle-low-rev-choppiness-problems.973293/post-2004112615

Here's an photo of 6mm silicon hose on Stepper and Throttle body. (from above thread).

View attachment 832146

Your throttle bodies are not the same as mine. The nipples are not in the same place and are larger. Trying to fit a 6mm hose on a 9mm nipple doesn't work on my bike. I appreciate your advice, but that's why Triumph used a 9mm rubber boot to connect my 6mm hoses to my 9mm throttle bodies.

 

 

9mm silicone hose used as a boot to fit my throttle bodies. Perfect tight fit. Located the hose from my ecu to my airbox. Will button everything up and get back on the road. Many thanks to all for your advice & wisdom.

 

On a 2nd gen 955 like yours the vacuum hoses should go from the IACV body on the throttle body to ports on the cylinder head, one for each cylinder by each fuel injector. The 9mm "nipples" on your throttle bodies are actually for the bypass screws used to balance the throttle bodies. I suspect someone has capped the ports on the cylinder head, removed the bypass screws and put the hoses on that way instead, obviously it's working for you but no way to balance the throttle bodies. Should you decide to replace the bypass screws Triumph don't sell them any more, but Kawasaki part number 16014-0002 is an exact match.

 

Just jumping on this thread very late and reviving it for two reasons:

1. Just as an aside observation. This thread according to the opening post is about a "2003 Sprint ST (955i engine)" and all the subsequent advice is about vacuum hoses and throttle bodies on the 02/04 engines, but when the OP posted a photo showing what he has, I think that looks like the throttle bodies on an earlier 01 engine which did have the bigger vacuum hoses on the front of the throttle bodies. In which case he doesnt have a 2003 engine.
Unless the Sprints had different engine model years to the S3 and the Daytonas?
Maybe thats why all the advice given didnt make sense to him?

2. But anyway my main reason for bringing this back from the dead is purely for selfish reasons

RampantParanoia said:
Should you decide to replace the bypass screws Triumph don't sell them any more, but Kawasaki part number 16014-0002 is an exact match.

Just preserving this quote on my history so I can find it easily because at some point in the not too distant future that part number will probably be worth more than gold to me

 

Post #15 shows a gen2 while post #25 shows a gen1. I think while late gen 1 have the same iacv, they don't have bypass screws as it's a differential butterfly instead. We can see the bf adjusting screws.

 

Post #15 shows a gen2 while post #25 shows a gen1.

That is a short simple, inteligent and straight forward translation of my long rambling explaination, but I also made the mistake of thinking the gen 1 picture was posted by the OP when in fact he posted the pic further up the thread og the gen 2 engine.

So I will take my quoted kawasaki part number and go and sit in the quiet corner

 

I just realize that you are the bowlofmice of THE bowlofmice site. Great and helpful site.

 

I am. Thank you. I've finally got my **** together and updated it too.