What colour is the smoke? Blueish indicates oil burning, blackish is excess fuel. It may be as simple as you are using the choke much longer than needed. Mine also starts and runs with minimal choke, as mentioned by the two previous posters.
Smoke on Startup
- Thread starter Samdoggy
- Start date
ST1100Y
Site Supporter
Same here, choke to ~1/2, hit the starter, once engine fires instantly back off the choke to ~1/4, by the time I got my first glove one the engine already "complains" (= idle drops!), so I need to back off the choke further to like 1/8 or less for stable idle, get 2nd glove on, mount and take off (gently, keeping revs <2800rpm)... by the time I'm at the first traffic light/intersection I've to fully back off the choke for proper idle; engine will then set steady at ~800rpm, takes another mile or so till it smoothly idles at 1000~1100rpm (it all varies with ambient temps and humidity... during >80?F in the summer I must not exceed 1/4 choke for starting and instantly back it off once it fires)
Well, flooding an engine will wash the oil film off cylinder walls and rings, having choke on for too long leads carbon deposits on crowns, rings, exhaust valves and spark plug electrodes... and of course is there increased blow-by contaminating the engine oil...
90% of engine wear occures in the first 10 minutes of start up. Thats my contribution to this thread. 
Slydynbye
Will ride for Pie
I think there is a noticeable difference between bikes with the Euro 40 idle jets and the US EPA 38 idle jets.
I upgraded one of my STs to 40 and find it needs less choke, idles better and is less cold blooded.
I upgraded one of my STs to 40 and find it needs less choke, idles better and is less cold blooded.
ST1100Y
Site Supporter
Seems logical, but even with #40 jets my mech enriched the idle mix by ~1/8th turn to eliminate "hesitation" during sudden load changes (i.e. quick shifting under heavy acceleration/passing) and the possible "cough" during heavy take-off after idling at a traffic light on hot summer days (I also installed the second air-duct to all my STs to deal with those vapour-lock symptoms in dense traffic during hot days).
I've been to 8900ft above sea level (Col de la Bonette, .fr) and had no bad side effects due the enriched settings (of course will engine power slightly decrease at such elevations), whilst observing many EFI equipped bikes suffer...
Dunno about folks in places like Colorado and such...
I start my bike each morning with as little choke as necessary. Most mornings 45+ degrees I only need 1/4-1/2 choke to start the bike. On very cold mornings 32-45 degrees it's 1/2 to full. After about 30 seconds it will idle (although a bit roughly) without any choke at all. I've always felt that I'd rather it idle a bit roughly without choke than leave the choke on. I've never left my choke on for longer periods of time to see what it would do. I may have to give it a try and see if mine smokes....
That supposedly step increase in pilots doesn't seem to be needed on my 92. No stumble, load-up with heavy throttle application at low rpm. Hot temps in slow moving traffic have had no ill effect, along with 52+mpg on other end of spectrum.
This has been at elevations ranging from 4,000ft. up to and including 14,100ft.........with a few runs to west coast@sea-level.......gotta love gettin' back that 3% loss of HP for every 1,000ft. elev......it IS noticable!
Yeah, that sounds like the early BMW K100s.
OP
OP
I rode yesterday and when I started the bike up I only used about half choke and then backed off as soon as the engine would allow it. I use the throttle lock to keep idle up. Started fine and no smoke Smoke was blue, btw, and not seemingly attributable to valve guides etc. as it only smokes on startup with choke on. Still not sure why it would draw oil on full choke, but at least I can run the bike without the smoke if I pay a little more attention to startup procedure. Interesting comments about idle jetting, I don't know what size I have on bike but will bring it up with a mechanic next time in. I live at sea level and most of the mountain passes around here are only about 4000 feet so high altitude jetting should not be a problem.
Smoke was blue, btw, and not seemingly attributable to valve guides etc. as it only smokes on startup with choke on. Still not sure why it would draw oil on full choke, but at least I can run the bike without the smoke if I pay a little more attention to startup procedure. Interesting comments about idle jetting, I don't know what size I have on bike but will bring it up with a mechanic next time in. I live at sea level and most of the mountain passes around here are only about 4000 feet so high altitude jetting should not be a problem.
ST1100Y
Site Supporter
Since the ST models over there feature an altitude control, there shouldn't be any issues at high mountain passes at all... unless the item is malfunctioning...
Slydynbye
Will ride for Pie
Altitude Control? You mean Constant velocity Carbs? Altitude control sounds like Fuel injection.
Hmmmm...I remember reading about an altitude compensating something-or-other in an article I read before I bought my first ST back in 1996. I'll see if I can find it.
+1..........CV slides DO help some with the vacuum loss at altitude.......from the 21-21in.@ sea-level to 18in.here@5.000ft........and in real-world,15-16in. of max. vac.@10-12,000t. (Through my work back then, had the use of aed gaug Mass-Port vacuum pump).
That's bout as far as it goes for any altitide compensation.....the CV carbs. BTW, the 3% loss of hp.for every 1000ft. increase in elevation IS spot on
.
John OoSTerhuis
Life Is Good!
The high altitude adjustment procedure is covered in the Honda Service Manual, page 5-16 in mine. For ST1100s operated continuously above 6,500'. Requires the Honda special pilot screw wrench.
John
John
Slydynbye
Will ride for Pie
I'm familiar with that adjustment. Is that what he meant? Sounded like he was referring to an automatic system.
I wonder why he said we have them over here, inferring they don't?
Thinking they are possibly covered with a cap and not visible if anything.
John OoSTerhuis
Life Is Good!
I was responding to Gymbo's post. The pilots screws are not 'capped' like many carbs are, but they are difficult to get to, hence the Honda special tool wrench with flex shaft. FWIW
John
via iPhone 4S
John
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ST1100Y
Site Supporter
Well, does all that extra plumbing and plastic boxes in there really only manage recycling of crank-case and fuel-tank vents???
Then disregard my post on this... (I was under the impression Cal emission regulations require altitude control on all carb engines, thus automatically implied its also mandatory on motorcycles...)
No such thing in EC spec bikes, tank vents directly into atmosphere (the hose ends above the side-stand), case vent is leading directly into the bottom the air-box... no filters, no check-valves, nadda...
And EC-spec idle screws do not require unique tools, an angled Philips #2 drive does the job
Thanks John. I just saw that in the service manual. Prior to my purchase of my first silver 1991 way back in 1996 I read in a article about the ST1100 and something that would compensate for altitude.....I think they must have been referring to the effect of the CV carb vacuum that Brant mentioned.
ST1100Y
Site Supporter
Confused me as well, as I did recall "something" on this matter...
Since the slides respond/operate by intake air-flow, will they prevent "unintended" richening when opening the throttle...
Still not a "perfect" system, can't recall the magical altitude level one should consider re-jetting/adjustment...