ST1100 Carb removal/rebuild

paulcb

paulcb

- - - Tetelestai - - - R.I.P. - 2022/05/26
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Joined
Jun 4, 2013
Messages
3,838
Location
Celina, TX
Bike
'97/'01 ST1100 ABSII
I've had a strong gas smell (off my ST1100, not me ;)) for over a year now. I could never find the leak, only maybe a little evidence of wetness on the rear of the carbs, at least what I could see. So, I finally decided to to pull the carbs and get this solved. With many thanks to Adam Frymoyer and his excellent tutorial on ST100 carb removal, I pulled the carbs yesterday and found a puddle of gas on the mat underneath. Still a bit of a mystery though as I couldn't really find any solid evidence of the source. In any case, I've decided to send my carbs off to Billy Carr in Canton, TX to have them rebuilt. He seems to have quite a good rep for Honda V-4 carb work.

A few pics from the removal...

IMG-4273 (Medium).jpg IMG-4274 (Medium).jpg IMG-4289 (Medium).jpg IMG-4278 (Medium).jpg IMG-4281 (Medium).jpg

The 2nd pic shows the leaked fuel puddle on the mat.

While I'm in there, I plan to do the following...

  1. Rebuild the carbs, as discussed above
  2. Replace the rubber boots/insulators (16211-MT3-000)
  3. Replace the float bowl drain hoses (16196-MT3-610, 16197-MT3-610)
  4. Replace the two coolant hoses (19504-MT3-000, 19506-MT3-000)
  5. Remove the PAIR system (maybe)
  6. Replace the rubber mat below the carbs (19050-MT3-000)
I'll use this thread to document what I can an to ask questions.

[-]So, my first question is what is the p/n of the rubber mat? I've searched all the micro-fiches, with no luck.[/-]

Found it... Honda p/n 19050-MT3-000. It's not cheap... $60-$80! I guess I don't have much choice, my old one came out in pieces.

Comments and suggestions are welcome and thanks in advance for your help.

-Paul
 
Last edited:
Q2...

The usual parts sources for the float bowl drain tubes are about $10-$12 per tube. Needing all 4, that seems a little excessive. Anyone have any better priced sources?
 
Carb overflows usually arise from worn float needles, which allow the fuel to overfill the float bowls and come out of the overflow drains. Fuel cap venting can play some part here too as heat soak from the engine will vapourise some fuel and create a bit of pressure with the engine off if the vent is sticky. There is a post on rebuilding the fuel cap on the ST-Riders forum.

I bought some replacement float needles from a Taiwanese source on eBay https://www.ebay.com/itm/4-x-CARBUR...ash=item4b0a2a9e6f:g:428AAOSw4shX~~9n&vxp=mtr and (touch wood) they are working well.

That Adam Frymoyer carb guide is a pretty amazing resource alright; certainly was very helpful for me, and Adam himself has been willing to give me some further set-up tips.

The other service item I would suggest is to replace the elbows and o-rings where the coolant tubes attach to the heads.
 
Re the mat, I don't see why it needs to be genuine. Get down to your tyre shop and get an old truck/ lorry inner tube and cut to suit. Even a large car tube may be big enough.
Hope it helps.
Upt'North.
 
agree with upt'North on the mat, there's probably a lot of different things you could use to replace that for next to nothing.

Don't forget to replace the coolant elbows along with the hoses, didn't see them on your list.
 
I've wondered about the mat material. I have some heavy rubber roofing material that I've thought of cutting (there is a template here somewhere), but not sure if it, or something else, would tolerate the heat.

Paul, radiator hoses not on your list. 19505-MT3-000 and 19505-MT3-00.
I just got all the stuff needed to do this work for the second time. The 99 this time around.
Also, there is the water pipe seal 91315-MT3-000 and o-ring 91311-KE8-00. I'm not replacing these this time. It was a pain.
Yep, don't forget the elbows and o-rings.
Probably not necessary to do the drain tubes, but then again why not. I didn't think of them the first time.
 
I looked at Adam Frymoyer's post on the other site and all I can say is that I hope I never have to tear down the carbs to clean or rebuild them. He makes it look very routine and easy, but I think it would be a challenge for the average guy doing this for the first time, even with the great tutorial.

I use Stabil + non-ethanol gas over the storage season, change the fuel filter every 4 years and the sub filter every 2 years so I think I'm doing everything I can to keep garbage and stale gas out of the carbs.
 
Thanks for the info guys.

TerryS said:
Carb overflows usually arise from worn float needles, which allow the fuel to overfill the float bowls and come out of the overflow drains. Fuel cap venting can play some part here too as heat soak from the engine will vapourise some fuel and create a bit of pressure with the engine off if the vent is sticky. There is a post on rebuilding the fuel cap on the ST-Riders forum.

I bought some replacement float needles from a Taiwanese source on eBay https://www.ebay.com/itm/4-x-CARBUR...ash=item4b0a2a9e6f:g:428AAOSw4shX~~9n&vxp=mtr and (touch wood) they are working well.

That Adam Frymoyer carb guide is a pretty amazing resource alright; certainly was very helpful for me, and Adam himself has been willing to give me some further set-up tips.

The other service item I would suggest is to replace the elbows and o-rings where the coolant tubes attach to the heads.
Click to expand...

Thanks Terry, I'll mention this about the needles to my carb guy Billy.

Why do you recommend to replace the aluminum elbows? I was considering replacing the o-rings but not the elbows themselves, just cleaning them up.
 
DeanR said:
I've wondered about the mat material. I have some heavy rubber roofing material that I've thought of cutting (there is a template here somewhere), but not sure if it, or something else, would tolerate the heat.

Paul, radiator hoses not on your list. 19505-MT3-000 and 19505-MT3-00.
I just got all the stuff needed to do this work for the second time. The 99 this time around.
Also, there is the water pipe seal 91315-MT3-000 and o-ring 91311-KE8-00. I'm not replacing these this time. It was a pain.
Yep, don't forget the elbows and o-rings.
Probably not necessary to do the drain tubes, but then again why not. I didn't think of them the first time.
Click to expand...

Thanks for the tips Dean. I found the template in this thread.
 
Mcreviver said:
Bulk hose. Just check your size before ordering. https://www.ebay.com/sch/i.html?_od...mm.TRS1&_nkw=Honda+bulk+hose+5mm&_sacat=10063

Rubber sheet. http://www.aircraftspruce.com/catalog/appages/rubbersheetpacking.php?clickkey=561350
Click to expand...

Thanks for that info. I think I'll order some of that material and cut my own mat.

My concern with bulk hose is that it might kink trying to make the turn from the bottom of the carb bowls to the 5-way tee, and I'm not sure I'd know if it did, since I can't see under there with the carbs installed. I guess I could dry fit it and see how it does.
 
paulcb said:
since I can't see under there with the carbs installed.
Click to expand...

Its been a few years, but I think you can see under the carbs if you removed the gas tank before removing the carbs. You might need a mirror to get the right angle, but I seem to recall that there was a certain amount of visibility under there after you put the carbs back on. Can't remember for sure though.

re: coolant elbows question, two reasons to replace them, 1) people have tried to re-use them and have had issues with them cracking, either upon re-installation, or shortly thereafter. 2) the original O-ring will be a gooey mess. For the few extra bucks they cost its not worth the risk of re-using the old ones, and you'll need new O-rings too.
 
dwalby said:
people have tried to re-use them and have had issues with them cracking, either upon re-installation, or shortly thereafter.
Click to expand...

I personally know one person that happened to. He was not a happy man, tearing it all apart again for two cheap pot metal elbows.
 
I replaced the elbows. They looked OK, but for about $8 each it seemed like cheap insurance vs. the time and effort to strip off the carbs again + the risk they'd crack somewhere far from home.
 
Mcreviver said:
Right. Not worth the risk to not replace them when in there if they are aged.
DSC02444.jpg
Click to expand...

I bead blasted the crust off my spare thermostat housing and found some pretty deep pitting underneath. I imagine you would find the same pitting on these elbows. If the pitting is extensive enough, these will always seep coolant, even with new hoses and clamps.
My long winded point is be thorough, especially when dealing with hard to access parts.
 
I've had a look at your pix. #4 float bowl seal is leaking. I could be looking at the picture wrong, but it appears by the screw heads, that someones been in there before. Let your carb guy know that you have an "emission bike" (California/ABS). The initial bench settings will be different. Plus you're running in the Texas heat...

Remember that once you get those fresh carbs back, you'll need to tune and synchronize. Good luck!
 
Thanks very much for the input guys... I'll guess I'll be replacing those elbows.

When I get the carbs installed, I plan on syncing them with my Morgan Carbtune. Is there anything else I need to do?
 
paulcb said:
When I get the carbs installed, I plan on syncing them with my Morgan Carbtune. Is there anything else I need to do?
Click to expand...

Thought I'd bump this.

The only thing I plan to do is install the carbs, set the idle and sync them. The rebuilder said he would bench sync them so they should be close.

Other than replacing all the necessary parts and syncing, am I missing anything regarding the carb setup?
 
afrymoyer said:
I've had a look at your pix. #4 float bowl seal is leaking. I could be looking at the picture wrong, but it appears by the screw heads, that someones been in there before. Let your carb guy know that you have an "emission bike" (California/ABS). The initial bench settings will be different. Plus you're running in the Texas heat...

Remember that once you get those fresh carbs back, you'll need to tune and synchronize. Good luck!
Click to expand...

Thanks Adam. I did tell him it was a CA bike. I'm good on the sync... please explain more on the 'tune' part?
 
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