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  1. #1

    SUV-1200 non-PV Carb tuning

    Hello

    Please advise with my issue.

    Engine runs and idling fine but bogging when pumping throttle few times from idle to full. However it doesn't die and becomes back to responsible after few seconds on idle. Low speed adjusters are open 1 1/4 for all and high speed adjusters 1 - 1 1/4 - 1.

    I have updated following items:
    Carbs are rebuild (with OEM kit)
    Low jets: 100
    High jets: 135
    Needle valves: 1.5 (with gold springs) Pop-up pressure is about 30psi.
    Fuel line restrictor with 105 jetting
    Choke plates are removed and Mikuni primer system installed
    Impeller: Solas Concord 12/18

    The engine is responsible and with full throttle gains 52 mph speed. I have tried to tune low and high speed adjuster without any success.


  2. #2
    Yamaha artisan Cutlass's Avatar
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    Your pop-off is WAY too low.
    With the stock air box, it should up around 65-75psi.
    With aftermarket flame arrestors it should be around 50 to 55 psi

  3. #3
    Thanks. Have to check pop off pressures next time I open carbs.

    Today I made quick test run and noticed that the issue exists during throttle pumping only if throttle is fully released in between. Pumping throttle from 1/4 to full open does not cause bogging.

  4. #4
    Yamaha artisan Cutlass's Avatar
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    Make sense because pop-off pressure affects the fueling from just off idle to about 1/4 throttle. Fix that pop-off and you'll be all set.

  5. #5
    With stock air box I have set pop offs to 65psi, however it didn't solve my issue.

    Engine does not accelerate properly from idle to full throttle unless performing smooth acceleration. I adjusted low needles about from 1/8 to 1/2 rounds more open and found that I can feel when pop off happens. I would say that throttle respond is very crisp from 1/4 to full throttle but this low end tuning makes me mad.

    The very same issue were existing with original low speed jets (92,5?-97,5?-100?).

    Please help, what I'm doing wrong. I have read Skips313 tuning guide from this forum and
    Last edited by Teme; 05-14-2013 at 05:45 AM.

  6. #6
    Yamaha artisan Cutlass's Avatar
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    how did you get 65 psi with the 1.5 NS. Did you switch back to 1.2 NS?
    Its hard to say whats wrong. you're in the right area for pop-off pressure. Did you pay attention to the needle arm height and get it level or slightly higher then the carb surface next to it?
    Can you tell if the pop off feels lean or does it feel like its loaded up rich?

  7. #7
    Yamaha artisan Cutlass's Avatar
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    Read the carb synchronization section on this Group K article, inspect your carbs, and cross this off the hesitation/bog check list

    http://www.groupk.com/y1100-1200updt.htm

  8. #8
    The issue was caused by fuel line restrictor and leaking reeds. I removed restrictor and changed reeds to V-Force3 reeds. After carb tuning it works extremely fine, top speed 57mph

  9. #9
    Yamaha artisan Cutlass's Avatar
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    So you drilled out the restrictions in the carbs and added the inline restrictor jet like the sticky thread said, correct? And now you don't have a restrictor jet? How could that possibly work ?

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