950ADV poor cold start

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by skandero, May 20, 2013.

  1. skandero

    skandero Been here awhile

    Aug 15, 2012
    Saint-Petersburg, Russia
    Hello, friends. I've got a problem with my adv950:
    when I start engine after the night (about 10-12 hours from the last ride), 2-3 minutes it is running at 1500 rpm, not more, the choke is at the half level (as described in the owners manual for the warm weather). Sometimes RPMs shortly jumps up to 1.6-1.7k, but falls back in a second or two. Also I hear popping to carbs, and sometimes backfire to the exhaust.
    If I fully pull the choke out, RPM comes to 2k (exact and stable), backfiring stops, but some popping still remains. The temperature at my region is really good, at about 15-20 C. The weather is clean and dry. Summer.
    When the engine reaches operating temp (three-four bars at the thermo), I can easily push the choke back, and no more backfires or popping will appear during the ride, even if the engine will be cooled down at the short stops. Until the next night stop.

    I replaced old spark plugs, cleaned and synchronized carbs, checked for possible air leaks (were not discovered at all), cleaned and oiled prefilter and main filter. Still got this shit on the cold engine.
    So, my idea is to adjust valves (looks like it's time to do, 16k+ miles passed). Looks like the cold gap is pretty large, and I have air mixture leak to exhaust and back to carbs on cold engine. When the engine is warm enough, the gap is normal - running and idle are perfect on the hot engine, no acceleration problems or stalls.

    Am I right? Any other ideas?
    Thanks, Ivan