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  1. #1

    2002 yamaha GP800r carburetor adjustment

    Ok can I adjust the carbs on this without removing the carb? I'm thinking it's running lean cause it runs like crap for the first 25 minutes or so and then finally starts running better. I have to have the choke partially pulled out to get it passed 4500rpm. It runs great up to about 3000rpm and then after that it starts bogging down and it will just stall if I keep giving it more fuel. Now if I blip the throttle a couple times I can get it passed that 4500rpm bogg and it will run good all the way to 7000rpm but if I back off to around half throttle it starts bogging again. Also I've noticed it's bad if I've been idling through a channel for 5 minutes then try to go fast again it will bogg bad even with the choke pulled out. Anyways. Do you guys think this is running lean? Also how many mixture screws are their and where are they? Let me see if I can find post the carburetor diagram and you guys can tell me where the high speed and low speed jets are and how many there are. Thanks! You guys can just tell me which number is which adjustment knob. Thanks.


  2. #2

  3. #3

    Join Date
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    Looks like #33 is your low speed adjustment (closest to the base of the carb and facing down toward the bottom of your hull... i. e. hard to get to without aftermarket adjustment screws)and #37 is the high (toward the top of the carb). Each carb has one of each. #39 looks like the anti tamper cap which covers the high speed adjustment.... you must take a punch or small screw driver and remove it to get to the screw.

    Sounds like you have problems on the low speed circut. When was the last time those carbs were cleaned and inspected? I mean, it is a 12 year old boat.

  4. #4

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    Sounds like the carbs are clogged. Have they been cleaned recently? You cant tune out a blocked passage.

  5. #5
    Is there only one low speed adjustment? You said each carb has one of each but I only see the one low speed adjustment on carb #2 according to the diagram here. Does that one adjustment screw do both carbs or are they only showing it once on the diagram?

  6. #6

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    Each carb has its own high and low speed adjustment.

  7. #7

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    33 os low speed, 37 is high speed. They both have both needles.. but you didnt say.. have the carbs been cleaned? Sorry if I missed it in another post.

  8. #8
    They were six months ago.

  9. #9
    I'm going to spray carb cleaner in the jets and hope the guys at the shop had it adjusted right. I guess they just set the carbs to a pre set factory setting and leave it.

  10. #10
    Echo's Avatar
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    If it was running good when you got it back from the shop, then it was/is adjusted right. Sounds like it has deteriorated over time in the 6 months since. If this is in fact the case then carbs are most likely clogged again, and simply sparying cleaner in any part of the carb is likely fruitless. The screens are most likely clogged from doing their intended purpose, and carb disassembly is needed to access/clean them. Continuing to operate in this condition could cause damage to internal carb parts, and cause lean fuel condition resulting in engine damage/failure.

    This is not to uncommen if the complete system was not flushed and cleaned. Tank, selector, and all lines should be drained/flushed at time of carb service. All that gunk and corrosion in the carbs is normally a result of factors throughout the entire system. If it was/is running good at time of carb service, and service is being done as a preventive measure, and assuming no major contaminates are found within the carbs then skipping the rest of the system could be acceptable.

    Personally i would get in touch with the shop and see if they have a record or perhaps remeber(unlikely they remeber you unless you stop in and BS. with them often. They have seen alot of skis in the last 6 months.) of what exactly was done at the time, as well as the condition of the carbs.
    In the future try finding out what things looked like, and possible reasons/solutions of adnormally dity carbs.

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