The bike Suzuki Intruder VS1400 model 2000, ran fantastic, but started to stall on idle when I used old fuel in it.

What I did:

I cleaned the two CV carbs. Didn't replace anything.

I found the floats too high, I adjusted them according to factory specs, about 2mm lower.

Resynchronized the idle and throttle using Carbtune from Morgan.

Adjusted the pilot screw using Colortune from Morgan also.

Symptoms now:

  • Idle runs great.
  • Little hesitant when snapping the throttle on neutral.
  • Under load, 2 gear and above, 1/4-3/4 throttle:
    • Hesitates
    • No power
    • Pops on acceleration
    • Heats up more than usual.
    • Gear rattles
  • On WOT, it picks up power after one second in WOT, but not as strong as before.
  • Spark plugs are yellowish but clean and dry. No signs of melting. but I didn't ride the bike other than 500 meters test drives.
  • I sprayed starter spray on the intake boots, no rpm difference, no intake leak as far as I can tell.

More information:

  • I can't tell which carb pops because both exhausts are on the same side.
  • The diaphrams are in good shape, I can lift the slide by blowing into the carb intake ventury, and it goes down normally, with some suction sound. which I believe to be good.
  • I cleaned it with brake cleaner and compressed air, it was already clean, no plugged holes anywhere.
  • I've repeated the procedure another time in case I missed a step, but no change.

Any ideas what could be wrong?

  • 1
    "I found the floats too high, I adjusted them according to factory specs, about 2mm lower." Put them back to how you found them, this may have been done to solve the issue you are having.
    – Moab
    Aug 11, 2020 at 15:55
  • 1
    You cleaned the carbs. You need to be scrupulously clean on that job. The merest whisp of a fibre in a jet can upset the carburation. Aug 11, 2020 at 21:41
  • @WeatherVane, you're right, I was, I learned that lesson from the past, all intakes and hoses are covered all the time to avoid any dust particles from entering.
    – Aus
    Aug 11, 2020 at 21:54
  • @Moab, yeah, I know it was either too high or too low, I can't seem to remember any more. But I'll try both directions and see.
    – Aus
    Aug 11, 2020 at 21:55

1 Answer 1


The symptoms you describe (hesitant, low power, running hot) point to a lean condition. It sounds like you may have set the floats too low, I'd set the floats back to where they were and see if that improves the situation.

  • Low float means when you put the carb upside down (almost), the floats are closer to the carburetor body, the distance was larger in the past, I brought them 2mm closer to the body. Which should mean more fuel in the bowl, doesn't it? I should expect the opposite effect shouldn't I?
    – Aus
    Aug 11, 2020 at 9:22
  • 1
    I'd assumed you meant that he adjustments you made were in relation to the normal orientation of the carb. I'd still put the floats back to where they were and see if that fixes it.
    – GdD
    Aug 11, 2020 at 9:26
  • Ok I'll do that, but it doesn't make sense.
    – Aus
    Aug 11, 2020 at 9:48
  • 1
    It's the one thing you changed @Aus. Going back to how it was eliminates that factor.
    – GdD
    Aug 11, 2020 at 9:52
  • 1
    "Low float means when you put the carb upside down" actually it does not. Low and high are relevant to the normal position of the carb. Low in the float bowl or high in the float bowl.
    – Moab
    Aug 11, 2020 at 15:57

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