Carburetor Cleaning/Soaking

Splash

Splash

Joined
Jul 30, 2007
Messages
49
Location
San Diego, CA
ST-Owners,

Hello! I am interested in obtaining any tips, tricks, cautions or concerns in regards to soaking the carburetor assembly of a 1996 ST1100A (California model).

History: The recently purchased ST1100 was stored during the past five years without any maintenance or exercising of the engine. The motorcycle had 3,300 miles on it. The carburetors were cleaned in 2004 by a local dealer.

Symptom: The engine runs rough above 3000 RMS. It is much worse when the engine in under a load or while riding.

Troubleshooting:
1. R/R carburetor assembly after cleaning low speed jets with Acetone. The high speed jets were cleaned or opened a with small wire. All carburetors were found in sync with each other.
2. The old fuel was drained and replaced with 91 octane and Tekron gas treatment.
3. The choke cable was inspected and is functioning properly.
4. The air filter is clean and there are no obstructions or impingements on the vacuum hoses. The small 1"x2" retangular sub-filter just forward of the airfilter housing was removed since it had deteriorated.
5. The engine oil was checked and is at the proper level.
6. Fuel filter was inspected and replaced.
7. Fuel pump was check for sufficient flow and is good.
8. The spark plugs were inspected and replaced with known good plugs.
9. All four spark plugs have normal spark and the tips look good. Dry & gray in color.
10. The ST1100 was ridden for 160 miles in order to run more than 3/4 of tank of gas with Tekron through the carburetors. Most of the mileage was on the highway at 4000 rpms.

Any carburetor assembly soaking advise would be appreciated. I am aware the rubber components should be removed. What should be used to soak the carburetor assembly and what is the recommended duration?

Thanks in advance for all replies and extra keystroks!!

David K.
 
Remove all rubber orings, diaphragms before cleaning? Carb cleaner will ruin rubber.
Assuming you have the pilot and main jet cleaned, and the bike doesn't make power above 4000rpm:
Are the float levels set proper? Float level too low the carb will run out of fuel (lean), too high too much fuel (rich).
Are the diaphragms lifting the main jet metering rod needles? They very well could have dried out and cracked. If these do not lift, the bike is running on the pilot circuit only, a main cause of power loss at WOT.
Open the butterfly plates and there is a series of tiny holes, remove a wire from a wire brush and rod them out.
Are the bowl vents open?

This may sound stupid, but do you have a proper air filter that seals. I have a 91 ST that runs great. Remove the air filter and the bike won't rev past 5000 no load. If the air filter doesn't seal (aftermarket auto filters) the bike is tooooo lean.

After I tear down a carb(s) I spray with carb cleaner and use a wire pulled from a wire brush and reem all holes and circuits, jets. Then blow out wit compressed air. They do not require a long soak, in my experience.

Lastly, but not least, are the valves set properly?

Somethings to think about.

Ralph Sims

Ralph Sims
 
One word: Seafoam. Put in your fuel, should clear out your problems, assuming they are in the carburetor.

Techron is not a carburetor cleaner, it is a fuel injection cleaner. Techron is great for removing really hard mineral-type deposits on injector nozzles. You need something that will dissolve the fuel residue. Not the same mission.
 
Atonic,

Good evening and thank you for a great link. The 90+ photographs and illustrations help a lot. "A picture is worth a thousand words...'

All, if you wish to learn more about carbs, check out this nice link!

Thanks again Atonic!
 
Ralph/BuddingGeezer,

Hello and thank you for the detailed reply. Everything is noted! Your reply is just what I was seeking.

I'll certainly check the float levels since the ST does appear to run lean. It's slightly noticable while parked at 2500 rpm's and certainly starved of fuel while under load above 3000 rpm's.

The diaphrams appeared to be in good shape two weeks ago. I'll certainly check the lifting of the main jet metering rod needles.

> proper air filter that seals<
I only use OEM filters. The air filter is sealed tightly.

I thought about the valves and timing as well. Since the ST only has 3,500 miles on it now, I doubt it's a valve issue. There's no sign of smoking or knocking/ticking. If the timing was off, I don't think it would idle and accelerate so nicely upto 2500/3000 RPMS. This afternoon, I went to the local dealer where the ST was serviced by the previous own and obtain the maintenance records. There were no services associated with the timing, thankfully.

Thanks again for such a detailed and thorough reply!

David
 
Don/CarSalesman,

Good evening and thank you for the timely response. I was just about to jump in and start removing the carbs for cleaning until I read your post. After a disappointing morning of riding with no change in results, I was sure the carbs need more 'hands-on' attention. However, I feel it's worth giving the Seafoam a try. I'll try to run another half of a tank of gas with Seafoam through the ST tomorrow morning. Hopefully, I'll have good news to report tomorrow afternoon and will not have to 'turn another screw'....regarding this issue.

Thanks again for your reply! (Btw, I think you have a very nice photograph with your significant other/wife.)

David
 
I'd seriously try the SEAFOAM treatment and do most anything to keep from pulling that huge lump of STuff out of the valley.

If you've cleaned the jets, and know it's synched, just running some good gas through it should help it out a bunch.

If you do decide to pull the carbs, you might want to consider replacing the 'boots' (called isolaters by Honda) as they have been known to crack and leak, resulting in the sort of symptoms you describe.

Next time I lift my carbs I will have to replace, I used RTV Blue as a lubricant the last time out. They were incredibly hard and I wanted to insure no leaks.

Oh, and while you have them out, be sure to check the coolant hoses under the carbs. They can be a serious PIA.

You might want to wait a little longer, let some of the ST 1100 guru guys check in. They will be here, just probably out riding on the weekend...
 
It worries me more that a dealer has already had a go at the carbs, so whether something went back together the wrong way is a possibility - never assume that the basics are right before seeking more complicated solution :). The carbs may just not have been cleaned properly, so trying a better cleaner is a start as the bike runs and carbs synched.
It is possible to have a hose around the wrong way, not allowing the carb slides to operate properly, or one or more of the vacuum hoses can come of while doing the carb synch checking (happened to me once!). The running rough above 3000rpm indicates a needle/needle jet and begining of main jet problem potentially, assuming all connections are right, which depend on the slides working properly. As mentioned, a simple vacuum leak can cause such issues.
The PAIR system may also be an issue, but as I don't have that wonderful feature someone else may have a view.
Assuming that all is connected in the right place, the vacuum fuel valve may be playing up, not allowing enough fuel through. If a fair bit of carb cleaner has been used in the fuel, this can foul the plugs enough to make it run really bad. Sometimes a change to a new set of plugs does wonders, but after the carb cleaner has been diluted down enough not to cause further fouling..
 
CarSalesman said:
One word: Seafoam. Put in your fuel, should clear out your problems, assuming they are in the carburetor.

Techron is not a carburetor cleaner, it is a fuel injection cleaner. Techron is great for removing really hard mineral-type deposits on injector nozzles. You need something that will dissolve the fuel residue. Not the same mission.
Click to expand...

Word of caution on seafoam - if you use to much the plugs will foul and you may notice a loss of two cylinders especially when cold. No damage will be done but you will have to pull the plugs and clean them if this happens. The small plugs used in the ST11 foul very easy so it's fairly common to develop intermittent misfires if the gas is old or contaminated with cleaners.

However Seafoam is good stuff and worth using.

Just checking - are you sure it is running on all 4? You may wish to verify all 4 are firing as every ST I have owned so far has had a bout of twin cylinder running.
 
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David, hope all this advice helps. This is the first I've heard that Techron is for injectors only, it'sjj been avavailable longer than injectors.

Give the Sea Foam a try and keep us poSTed.

The mattress is great, much more comfortable than my old one.

On my Acer, at the Javalina Cafe' in Silver City, New Mexico.
 
Troubleshooting Continued:
11. Rode 160 miles with Techron. No change in status.
12. Rode 200 miles with two cans/pints of Sea Foam. Resulted in improvement in 2500-5000 rpm range while the engine is not under a load. No improvement in the >3000 rpm range while under load. The 200 miles were mostly highway miles with rpms mostly between 4000-5000.
13. After the Techron & Sea Foam treatments, the spark plugs still look good.

BigTom: I think you may definitely be onto something with the boots/isolators. Since the motorcycle was mfr'd, the carbs had been reinstalled three times, twice during the recent cleaning. The coolant hoses were checked. Most clamps needed 1/4 - 3/4 turns to tighten....on a practically new motorcycle. I also added better clamps where necessary. I am going to order the insulators tomorrow. A lot of force was used to seat the carburetors into the isolators. Perhaps their age and the frequent carb cleaning cracked one of them. If not, the root cause may be some very stubborn gunk in the carburetors. (Hopefully, I'll be able to inspect the insulators later tonight.)

Saaz: Thank you for your post. I will be very careful with identifing, labeling and tracing the vacuum hoses. The manual has a decent illustration to reference. I may consider removing the vacuum system since this motorcycle is destined for Ohio in a couple months. I have two other ST's to cross reference so I should not have a problem.

Storm: As mentioned above, all four plugs look good and all cyclinders are firing. That was the first thing I checked after the ST awoke from a five year nap. Thanks for the suggestion. I am going to order new plugs as well as filters.

George: Hello and thank you for writing. I am guessing this may be a failed isolator. Anyhow, I am getting real familiar with removing the body work and carbs. It gets easier everytime... Btw, I am happy your sleeping better on your "Dreamtime". It's nice to learn it's going to get a lot of use during your travels. Take care ride safely.

I'll keep everyone posted....although it may be a couple days.

Happy Easter Sunday!
 
Hey Splash...

Sounds like you're getting good help here. Couldn't help noticing that on your troubleshooting list, you haven't tried bypassing that Vacuum Fuel Shut off valve yet ? Or you did and didn't mention ?

Maybe small tear in that diaphram is reducing fuel supply ?
 
Troubleshooting Continued:
14. Vacuum Fuel Shut Off Valve: Installed the potentially failed vacuum fuel shut off valve on another ST1100 motorcyce and was unable to reproduce symptoms. (Thanks for the suggestion ChrisK!)
15. PAIR hose installation was verified with another CA ST1100. - everything was installed properly.
16. Removed carburetors: cleaned pilot jets & main jets with acetone & boiling water; cleaned diaphrams; removed & inspected floats; used compressed air on all orifices; The inside of the carbs looked as clean as a stainless steel whistle. I don't think there's a need to soak. All orafices appeared open. The jets appeared clean after blowing compressed air through them. Initially, light was not passing through a couple of them and I am unsure if it was simply residual fuel. While re-assembling, I noticed one carburetor body cover was not installed with the proper orientation. This may have prevented the small vacuum hole and associated diaphram to function improperly. Also, between the #3 carburetor's pilot screw and the isolator, there are two holes which should have a bearing-like steel ball visible from the exterior of the carburetor. One of the two ball-bearings is missing. This may have been dislodged while forcing the carburetors onto the boots a couple weeks ago. It appears to sit against the isolator. If the bearing can't be located, I'll attempt an install without it.
17. Carburetor Isolators: inspected and replaced all isolators/boots; The original isolators looked like new without any cracks.
18. Spark Plugs: new iradium spark plugs will be installed tomorrow
19. Air filter subfilter: small rectangular subfilter was replaced.
20. Air filter housing: new seal will be installed.

All in all, I am hoping the misaligned carburetor cover may have contributed to the poor running above 3000 rpms.

Final results to follow tomorrow.
 
Today is a day of mixed emotions and results.

First of all, the recently cleaned carburetors were installed and the spark plugs were replaced. The initial 3 mile test ride with rev's up to 6000 RPM's indicated that the rough or sluggish motor performance experienced above 3000 RPM's is no longer present. I suspect the issue was associated with the carburetor cover and or the main jets. Great news!

The bad news... really bad news:

Prior to taking the test ride the motorcycle idled quietly and ran normally for a short trip around the block upto 4000 RPM's. In order to dilute the sea foam which was used in the gas last week, I purchase 2.5 gallons of gas from Chevron (?) (which happens to have techron in it). While taking the test ride, the ST1100 engine started to make a noise which increases with RPM's! Initially it sounded like a fan or something since it is a higher pitch noise coming from the front of the motorcycle. It's not a knocking sound I associate with an engine rod or something (my only experience is with V8's).

Question 1: Is there anything in 87 Octane Chevron gas with Techron that would not mix well with Sea Foam? This knocking or pinging only appeared after getting gas. Perhaps running the bike upto 6000 rpms exposed something...?

Question 2: Is there anything that could have fallen from the carburetor into the engine? I know it would be rare... During the test ride there was a moment of hesitation in which I thought the carburetors was 'passing' something... but it quickly passed and the ST1100 continued running without hesitation.

I can't imagine anything from the carburetor causing damage to the engine. The noise is very loud and I don't even want to start it again to troubleshoot it. It sounds like it is doing some damage to the top end...

I'll inspect the plugs (and valves) and may replace the gas. Any suggestions or help would be greatly appreciated. I am not really sure where to start...

Thank you!
 
Just to clarify: the only change to the motorcycle between the initial short ride around the block was the replacement of the spark plugs and the adding of 87 octane gas with Techron. I may re-install the original plugs as well.

After a bit of browsing on the forum, I am learning that the carburetors may need sync'ed. I will check the carbs with the sync tool (from Germany). Also, I wonder if the missing ball bearing.... located near the pilot screw could be the source of the noice or issue?

It's hard to believe nonn-sync'ed carbs could make so much noise.

More to come...
 
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Inspection Update:

The engine knocking was not due to bad gas, or gas with techron and sea foam.
The engine knocking was not due to the carburetors being out of sync.

The engine knocking was the #1 piston hitting the spark plug.
 
Splash said:
Inspection Update:

The engine knocking was not due to bad gas, or gas with techron and sea foam.
The engine knocking was not due to the carburetors being out of sync.

The engine knocking was the #1 piston hitting the spark plug.
Click to expand...

Why? :mw1:
 
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