Need some carb advice?

Remove both panniers, the seat, both side panels and the false tank.

Then check if the choke cable is fully attached and properly adjusted so the linkage + flaps really go to OFF when you move the choke lever accordingly.

then check:
- auto fuel valve
- any leaks in the vacuum lines
- carb isolators OK or cracked/leaking
- proper spark on all 4 cylinders/replace the spark plugs
- full fuel supply
- air filter
- sub air filter
- carbs synced

if that all doesn't circle down on the trouble, pulling and overhauling the carbs might be due... but I'd first cover the simple things...

What is the carb isolator? Thanks st1100y

hotrod1 said:

What is the carb isolator? Thanks st1100y

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The rubber parts that connect each carb to the engine.

hotrod1 said:

What is the carb isolator?

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Actually insulator, sorry for the typo...

P/N 16211-MT3-000, insulator carb, 4 pcs required (2 on each engine head)




Connecting each carb body to the intakes...
http://www.cmsnl.com/honda-st1100-pan-european-1992-austriakph_model4734/partslist/E__0300.html#results

Being a '94 model, I would start by pulling the carbs, if nothing else but to check the isolators/insulators whatever, and to check all the water connections under the carbs. While off, invert the carb assembly and pull bowls and remove the jets. Boil the jets in a water/pinesole mixture to clean them and reinsert in the carbs. Replace the insulators if they are not supple. After re-installing the carbs, continue to run some seafoam through it to clean up any other passages in the carbs. Oh, while the carbs are off, pull the vacuum piston covers and check the diaphragm in each one to make sure there are no tears. Again, after installing the carbs, then sync them. If you slowly rev the engine between 1K and 3K (slowly) if the carbs are clean and synced well, it should run smoothly at all rpms. If it stumbles, then keep running the seafoam for a couple thousand miles, it should clear up, then re-sync the carbs again when all is better... it should run like a raped ape, then!

Hey Rod... A fresh bike requires a fresh service. Start with the basics. FULLY service the engine before condemning anything. I agree with Martin. Replace all the filters and plugs. Valve clearance check and synch the carbs. Give us a ride report when she's fully tuned....

ST1100Y said:

Remove both panniers, the seat, both side panels and the false tank.

Then check if the choke cable is fully attached and properly adjusted so the linkage + flaps really go to OFF when you move the choke lever accordingly.

then check:
- auto fuel valve
- any leaks in the vacuum lines
- carb isolators OK or cracked/leaking
- proper spark on all 4 cylinders/replace the spark plugs
- full fuel supply
- air filter
- sub air filter
- carbs synced

if that all doesn't circle down on the trouble, pulling and overhauling the carbs might be due... but I'd first cover the simple things...

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+1 on that enricher cable housing hold down......BTDT.......threw me for a loop for a couple minutes as to why that enricher lever easily rotated on first portion of its travel.......until finially it 'argued' with me not starting easily when cold. Was nice to know cable itself hadn't went array on the rotating retainer 'wheel'.
When a seller says 'rebuilt the carbs'......normally not a good thing to have to do a followup on. In the automotive world, used to hate when someone would bring me carb. and tell me they rebuilt it. Almost 99.9% of time, they'd been better off to left it alone, and made things ALOT easier for me....just sayin'.

I see Vinny covered the rest....and by ALL means, replace those dang carb boots!......slightest vacuum leak around that base mount of them, and it'll have ALL the symtoms your experiencing, guarenteed! On top of that, a correct idle mixture and sync. will NEVER happen until new ones are installed, knowing for SURE there is a good seal in that location.
BTW, any vacuum leak can and WILL eventually hole a piston.
ALL cycles have been set-up and designed to be 'lean burn' since 1980........sure don't want to add to that!

Thanks, I now have a place to start. In the process of the above most of the day. Will let you know the results in a few days. Thanks again, Rod

+1 on the above. Check also for dragging brakes, especially the rear brake. And the fuel pump output. See this article : Fuel Pump Output

If you have rust in the tank the fuel filter could be blocked with debris,would also open bowl drain plugs to see if there's any sentiment in there.I had rust in my tank and tried to do a lining but the tank is so big and odd shaped that it was cheaper to find a clean tank on EBAY for $50.

When I bought my first 91 in 93, the fuel filter was clogged. Since then, multiple times we've had clogged low-speed jets due to sitting too long. Just this past Wednesday/Thursday helped Mark with a carb refresh, low speed jets were pretty much plugged. All is good now.

Thanks. Scrubbed the tank and will install with fresh filter after the carb refresh. It sounds like everyone says to replace the insulator boots, so I guess I will. I'm not quite sure how many turns on idle jets are recommended. Hopefully get this done by Monday and resynch. Great advice above......Thanks Will let you know how it turns out.

hotrod1 said:

I'm not quite sure how many turns on idle jets are recommended.

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Consult the workshop manual for the initial settings, from there work with the "idle drop" method.

You need a meter that will read RPM's down to 50 RPM increments to do an Idle Drop.In leiu of that,set them to two turns out.

Got it!