1994 ST1100, coolant leak under carbs, what all should I change?

Ace

Ace

Joined
Apr 29, 2011
Messages
41
Location
Kenosha, WI
Bike
1994 ST1100
Hi everyone,

I have a 1994 ST1100 with about 47k miles, overall in good shape. I had the infamous coolant leak under the carburetors. Got towed home. :( First break down since I bought the bike in 2001, so I can't complain...

Removed almost all the plastics. A friend helped me remove the carbuterators. Root problem was easy to identify, the right hand hose had developed a hole and leak.

I read the other related posts on this thread, also looked at John O's pictures (thanks John!).

A couple of questions:

1. I've already got everything apart, so what all should I change at this point? I'm not a great mechanic, so maybe I should just replace the left and right cooling hoses and wait to do the rest at the next Tech STOC! :D Seriously, I was thinking of also changing the bypass hose, upper and lower radiator hoses, thermostat, fan cooling switch, and radiator cap. I'm hoping I don't need to change my metal elbows, or should I replace them based on age?

2. Do you recommend using Honda (OEM) parts for the replacement hoses? Reading the postings, it sounds like a few folks have used straight hose or gone to a parts store to find a close match, but I am guessing most people are replacing with Honda OEM hoses.

3. It sounds like people recommend changing the carburetor boots while I'm in that far.

4. Also while I've got everything exposed, should I open up all the electrical connectors? Maybe clean them with contract cleaner spray? Then add dialectric grease to each?

5. I'm going to have to flush and fill the radiator while I have it all apart, because I added a lot of water trying to find the source of the leak. Should I just flush with water or 50/50 water/coolant? Or is there a cleaning solution I should run through the bike first, then rinse it out before filling with Honda coolant mix?

6. Should I replace the spark plugs at this point also? The plugs were probably replaced 5-6 years and 20k miles ago. If so, what plugs do people recommend?

7. Probably time to change the air filter, it was probably changed when the spark plugs were changed. I ride in a pretty clean environment, all highway, no gravel or dirt roads.

Thanks all!
 
1) I would do just the hoses and wait for the next (because I don't mind pulling it apart!).
2) Honda parts will be more expensive, local parts house will be quicker and cheaper; but, more of a pain because you have to mix and match.
3) Mine were not cracked so I put some silicone grease on them and reused them.
4) I didn't mess with anything that was working... just saying!
5) flush, I used hose water; then when it was clear, I filled with 50/50.
6) Iridium plugs last 100000 miles... so if they are Iridium... leave them alone!
7) Do it.

Good Luck!
Mark
 
I just replaced the hoses and boots. The boots on my '97 were dried out, which would have made reinstalling the carbs more difficult. Since your bike is a few years older it might be wise to replace the boots while you have the carbs off the bike.

I went with Honda OEM boots because most aftermarket suppliers will either not ship to Canada, or the price is about the same as OEM once you get done with shipping, duties and brokerage fees. The Honda boots were not that expensive anyway, so I figured I might as well just shop at my local dealer. I got the hoses at the same time and also picked up a variety of fairing clips, which I found to be missing during disassembly.
 
Be sure to check the cast "elbows" that attach to the heads; these have been know to leak. Only replacement for them is OEM. I would not mess with the other hoses etc unless they look cracked or damaged. Same with the temp switch, etc.

2.) If the coolant hoses are mostly straight, use properly sized hose from the auto parts store. If there are some pretty sharp bends molded in, then go OEM.

3.) I would inspect the carb boots closely. If they are stiff or cracked; replace. There are some aftermarket ones available that a few have used with no issue that I'm aware of.

4.) If you have not upgraded to a 40amp alt, make sure to check the connections at the regulator. Also, check the starter relay/main fuse and any ground connectors you come across.

5.) Flush with water, drain, then fill with a proper coolant/water mix. I personally will not buy 50/50 premixed antifreeze (what a rip!)

6.) If the plugs are platinum or iridium, don't bother replacing.

7.) Yep, change the air filter.

If you are due (8K miles) change the oil. You might want to inspect/lube the shifter linkage. IF you are ambitious or don't know when last checked, you might consider checking the valve lash.

Good Luck!!
 
Ace said:
Hi everyone,

I have a 1994 ST1100 with about 47k miles, overall in good shape. I had the infamous coolant leak under the carburetors. Got towed home. :( First break down since I bought the bike in 2001, so I can't complain...

Removed almost all the plastics. A friend helped me remove the carbuterators. Root problem was easy to identify, the right hand hose had developed a hole and leak.

I read the other related posts on this thread, also looked at John O's pictures (thanks John!).

A couple of questions:

1. I've already got everything apart, so what all should I change at this point? I'm not a great mechanic, so maybe I should just replace the left and right cooling hoses and wait to do the rest at the next Tech STOC! :D Seriously, I was thinking of also changing the bypass hose, upper and lower radiator hoses, thermostat, fan cooling switch, and radiator cap. I'm hoping I don't need to change my metal elbows, or should I replace them based on age?

2. Do you recommend using Honda (OEM) parts for the replacement hoses? Reading the postings, it sounds like a few folks have used straight hose or gone to a parts store to find a close match, but I am guessing most people are replacing with Honda OEM hoses.

3. It sounds like people recommend changing the carburetor boots while I'm in that far.

4. Also while I've got everything exposed, should I open up all the electrical connectors? Maybe clean them with contract cleaner spray? Then add dialectric grease to each?

5. I'm going to have to flush and fill the radiator while I have it all apart, because I added a lot of water trying to find the source of the leak. Should I just flush with water or 50/50 water/coolant? Or is there a cleaning solution I should run through the bike first, then rinse it out before filling with Honda coolant mix?

6. Should I replace the spark plugs at this point also? The plugs were probably replaced 5-6 years and 20k miles ago. If so, what plugs do people recommend?

7. Probably time to change the air filter, it was probably changed when the spark plugs were changed. I ride in a pretty clean environment, all highway, no gravel or dirt roads.

Thanks all!
Click to expand...

Replacing hoses since one was found bad is all good. DEFINITELY replace the two coolant elbows and O-rings! They're only $8 apiece!. If not, that WILL be the next leak area. Replace all four carb boots too, as the originals won't seal properly and will cause you fits trying to re-sync carbs. Less than $40 for all four OEM.
 
I just went through this whole process just a couple of weeks ago. I originally thought that it was my thermostat. Replaced it but a week later the temp gauge pegged. Crippled home after trying to go to WeSTOC (515 miles round trip garage back to garage), and started the 'tear down'. I replaced both elbows w/orings, the 2 hoses to the thermo housing, the carb boots and a new radiator cap. B/4 buttoning it back up, plastic on, I replaced the filter and put Iridium plugs in as they hadn't been changed in 48k miles and changed the oil. When I took the carb bank off I didn't remove any of the throttle/choke cables, just took the whole unit off and tie-wrapped to frame while doing the work. With the new carbs boots the carbs litterly slide back on after a gentle back and forth. My only problem was forgot to hook up the carb drain hose and couldn't reach under the carbs to get it back on. Had to remove carbs again to hook it up but carbs went right back on.

So with all the new parts that I got from Ron Ayers I think it cost me maybe less than a couple hundred bucks. And now the ole 1100 runs like a new bike again. I am going to do a carb sync in a couple of weeks to see if I can improve my 47 mpg that I have been getting. And I still get 37 mpg pulling my Aspen Sentry camping trailer.
 
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Thanks Irish,
I won't know till I get the carbs off what the boots are like,hopefully get stuck into it this week, broc11
 
broc11 said:
Thanks Irish,
I won't know till I get the carbs off what the boots are like,hopefully get stuck into it this week, broc11
Click to expand...

It's aged enough that replacing them irregardless is the better choice.....cost for me was $40, including the two elbows and O-rings...all OEM from local dealer. Replace each seperatley before removing all of them so they can be located the same orientation to access the clamp screw. Before installing carb bank, spray inside of boots with silicone. Reccomend you not use grease or petroleum based lube. It will cause them to harden combined with the heat under there.
 
Brant said:
It's aged enough that replacing them irregardless is the better choice.....cost for me was $40, including the two elbows and O-rings...all OEM from local dealer. Replace each seperatley before removing all of them so they can be located the same orientation to access the clamp screw. Before installing carb bank, spray inside of boots with silicone. Reccomend you not use grease or petroleum based lube. It will cause them to harden combined with the heat under there.
Click to expand...

+1 here. I replaced the boots although the stock ones were in pretty good shape. It just doesn't cost that much to replace them instead of having to go back in later to replace them. DIRFT-Do It Right First Time. Some thing I got from the working world.
 
Brant said:
It's aged enough that replacing them irregardless is the better choice.....cost for me was $40, including the two elbows and O-rings...all OEM from local dealer. Replace each seperatley before removing all of them so they can be located the same orientation to access the clamp screw. Before installing carb bank, spray inside of boots with silicone. Reccomend you not use grease or petroleum based lube. It will cause them to harden combined with the heat under there.
Click to expand...

I see they are $12.37 Plus vat and shipping per carb boot,from davidsilva
 
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broc11 said:
I see they are $12.37 Plus vat and shipping per carb boot,from davidsilva
Click to expand...

Not a bad price. With my 'local' small discount, dealer got them in for me at $8 a pop earlier this spring. Not even worth puttin' back in service for that price new.
 
Mark said:
eBay has them too.
Click to expand...

Good find Mark. Those are the ones I have gotten for both the 97 and the 01. They were out for a while, good to see them back.
I had read where the bands did not tighten any tighter with new OEM boots. I could be wrong on that but that is what i recall. Anyway,,, the ones I got through the folks you linked to were larger O.D. and the bands tightened up nicely.
 
Bigmak96 said:
Good find Mark. Those are the ones I have gotten for both the 97 and the 01. They were out for a while, good to see them back.
I had read where the bands did not tighten any tighter with new OEM boots. I could be wrong on that but that is what i recall. Anyway,,, the ones I got through the folks you linked to were larger O.D. and the bands tightened up nicely.
Click to expand...

IMO, the 'stops' on the clamps are intensional when used on the OEM carb boots. Since boots are 'locked' in an upper and lower groove, this may keep them from being overtightened causing a slight distortion.
 
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