Bought second ST 1100 and fixing some problems.

I could not pass up this 94' ST11 with 11k miles on craigslist two weeks ago. I knew it to be running a bit rough, it seems a little better after the Seafoam Rx, however its still choppy and rough. Noticed some back fires on deceleration and its just real boggy. I know the bike sat for some time, PO son is a mechanic and went through the carbs to get it going. He did not know anything about syncing the carbs but He did use a temperature gun to check the head pipe temperature, and adjust. Also, looking deep into the tank I noticed RUST. Probably from the long nap it just took.
In the meantime, my brother is flying in for a Yosemite Park trip next month, so I need to get them ready for the road.
-My plan is to clean up the tank-remove all rust
-New fuel filter and new fuel
-Already changed oil and oil filter
-Replace air filter and sub filter
Now run the bike for a bit and see how it responds to the above, probably do another Seafoam treatment then:
-Sync the carbs
-replace plugs
Run the bike again and recheck results

Other than completely removing an working the carbs, What else should should be priority to get this bike off the boggy and choppy list.
If I can get it to really purr, I will do the same to the other bike. Your input here is appreciated!
........Thanks Rod

I don't know exactly what boggy and choppy feels like, but it sounds like it could also be ignition related. A bike that old, with that few miles could have lots of different things wrong with it from lack of use. Also sounds like the PO son wasn't much of a motorcycle mechanic, carbs sound like a big unknown given his 'adjustment' techniques.

hotrod1 said:

What else should should be priority to get this bike off the boggy and choppy list.

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Likely some vacuum leaks, maybe perforated diaphragm in the auto fuel-valve, partially clogged jets...
I'd also check all fluids and filters, valve clearances, carb boots and, after cleaning, a decent carb sync.

Besides the above mentioned items, the brake and clutch fluids probably need a good flush... at minimum. It's possible the calipers may need to be taken apart, cleaned and have new seals put in them.
Out of sync carbs can give some of the symptoms you describe, vacuum leaks from the carb isolators being old and dried out. It is possible the carbs might have to be gone through again... but you might wait on that... The PO's son may have cleaned the jets. When you remove the carbs to replace the isolators, pull the polished metal covers off the vacuum pistons and check the diaphragms to make sure their not split. Also check the air sub-filter (the little foam 1" x 2" in front of the air box that has the two large hoses running to it) That little guy keeps the junk out of the vacuum pistons. Keep running the seafoam for a while after you sync the carbs. Good test after syncing the carbs... from idle with the engine warm and in neutral, slowly increase throttle from idle to about 3K... if the jets are dirty, it will stumble. If you hear what sounds like a mechanical knocking, then the carbs are not synced right.
The next big thing to check... tire age, then check the spyder coupling in the rear and the splines for wear. I believe the 94 still had the metal thrust washer ... all that stuff needs a good application of moly.

Wow that sounds like a fun project with a bike that is almost like a new one. Get some of the maintenance items done and it sounds like you found a gem there.

Sounds like a good plan, including the additional suggestions.

Just for S&G's , I would cut open the old fuel filter to see what's inside, as far as rust, etc. And check the compression, too. Make sure the carb slides are manually held open when doing that. If you don't have decent compression, no amount of other work will help the overall running.

Sounds like you found a potentially great bike. Have fun & good luck.

Thanks for the suggestions. I have most of this stuff on the list, reading up on syncing and carb assembly. Did buy an fuel cut out gauge re-build kit as well. The fuel filter looked like a dust storm in a bottle. It does need tires as well, have the rear need to order the front. Hopefully I can get it tuned right. If there is anything else, let me know. Thanks ... Rod

dwalby said:

I don't know exactly what boggy and choppy feels like,

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Boggy and choppy are technical mechanical terms. You need one of those specialized dictionaries.

Brake fluid looked recently changed. Clutch fluid was brown, gooey on the bottom. Hooked up the plug-n-play headlight modulator.

hotrod1 said:

Clutch fluid was brown, gooey on the bottom.

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Which would actually be quite a motivation to rebuild the slave cylinder... before that sucker starts to act up or even leak...

Perhaps on the slave cylinder. Still knocking out items on the list. Today I replaced rear tire, final drive oil, o-rings, splines look new, re lubbed with moly. Brakes look good. Ordered front tire.

hotrod1 said:

Update:

Replace both tires and changed most fluids. Pulled carb bank and each carb was filthy, PO used orange sealant on float bowls and the floats were covered and gummed up with that stuff, all the float were at different heights, I set them all to 7mm. I followed Adams carb procedure. Pulled rusty tank and scrubbed for hours and then lined with Red Kote tank sealant. Replaced all filters. Started it up today and synced the carbs. I noticed a fuel leak dripping from the bottom of the bike, I was concerned and could not find the source. I started it up again and leak disappeared? Strange?
After making the adjustments today, she seems to be running smooth. Rich smell went away, and no more back fires.
I still need to flush coolant system, possibly replace t-stat, and replace plugs.
Thanks for all the tips.....Rod

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I would hope you replaced the carb intake boots, coolant elbows/o-rings while having the carb bank off.....ESPECIALLY the carb boots!

Yip, new carb boots installed, the old ones were very hard as compared to new. The coolant lines looked new, I left them alone

Update:

Buttoned up all the plastic tonight, this is a what I did,

Remove rust from tank and covered tank in Red Kote
New tires front and rear, lubed rear with 65 moly
New final drive o-rings and gear oil change
pull carbs; cleaned, adjusted bowls, new boots, diaphrams look new
Synched carbs
All brake and clutch fluid flushed and new
new oil
new air filter, oil,filter and carb breather filter replaced
new irridium plugs
Rebuilt vacuum fuel valve
synched carbs again before button up
installed brake and headlight modulators
Coolant flush with new fluid
and new t-stat ant rad. cap

Going for a ride tomorrow. She sounds nice. Hopefully ready for a ride through Death Valley in a week, +120 f temps ..........Rod

Radiator overflow tube, it cracks in the 1st inch after the radiator.
It might be okay; but, be ready to cut an inch off if the overflow container fills and overflows...