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  1. #1
    Polcat2000's Avatar
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    Keihin single carb adjustment for stock 700cc 2000 Virage

    Ok...I just had the carb rebuilt when the CDI was replaced. I took it out in the water for the first time and it seems to idle fine, a little high, but fine. When I smash the gas it feels like its bogging for too long before the "power band" kicks in (no diff when I ease on the throttle). For the first few times it seemed OK, but as it got warmer, it got worse. Then its intermittent. You can almost count 6-8 secs before it kicks in sometimes. Then she revs up to about 6,000 rpm's and seems to run smoothly. As soon as you come off the power band it struggles to get back...not very responsive..

    I was reading through some threads on carb tuning, but I am still confused. I don't really know what does what, but I am a pretty quick learner...lol The guy who rebuilt the carb said he worked on wave runners, but does mostly motorcycles. The carb was set in his shop...not on the water..

    Is there an "Army proof" way of explaining to me what my best on the water options are? Maybe start from stock settings then work out? There are two screws, one with a long thick black knob and the other is a small flat screw. I know there isn't a high adjustment on this carb.

    Its a single carb for 2 cyls....looks pretty simple. I just couldn't find decent pictures...to see what adjustment did what.

    Thanks in advance for any help...
    Last edited by K447; 05-11-2011 at 09:44 PM.


  2. #2
    Polcat2000's Avatar
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    Nothing.....?

  3. #3
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    post in one of the other sections,this is more or less a library.

    its a single carb right??

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by TxPro1200 View Post
    post in one of the other sections...
    Moved to General Discussions.

  5. #5
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    WHen you say bogging, is it stumbling and sputtering, or just falling flat on its face? If its sputtering its rich, if its falling on its face its lean. Does pulling the choke help?

  6. #6
    Polcat2000's Avatar
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    Thanks for getting this in the right section K447...

    Yea its more like a sputter and a delay really. Yes TXPro, its a single carb. I actually didn't think of pulling the choke on the carb to see if that made a difference in my throttle response... Thats the main issue here. It doesn't seem responsive at all. Even after I come off the power band, to get back up is asking a lot it seems. Once there, it feels pretty good...

    Can I assume that if theres no high jet adjustment then the settings would be somewhat basic? As the carb is pretty basic..Like a baseline setting and minimal adjustments from there (like out of the box)?
    When I start it up, I cant hardly hold it back at idle if I'm off of it.. it wants to pull away pretty hard..The tach reads somewhere around 1000-1100 r's or so...roughly.. Is that normal? Is 6000 rpm's good under full throttle? I am missing the speed sensor, so I really don't have a clue how fast I am going, so I really am just going off of performance and feel at this point.

    I guess I am asking a few questions here..lol but I welcome any advice you guys can give me. It was fun while on plane...not like my Yamaha 1100, but for the girlfriend, its plenty.. I thought it rode pretty smooth in the water..Nota speed demon, but I'm looking for fun...lol

  7. #7
    urugol's Avatar
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    You could have a rich condition from what you are saying, does it smoke like hell on idle? As in more than a regular 2 smoke engine? If you feather the throttle does it respond a little better than pinging down the throttle? Any number of things could be the issue here, good thing is you only have 1 carb to deal with not the regular 3. Keihin Carbs (which is what you have) do not have high speed screws, the low speed screw is adjustable for the first 1/3 or so of throttle response and that is where your problem is. Things I would look at are, 1. Check the seating of the low speed screw I would try turning it in half a turn then ride see if it makes a difference, if not turn in another half if you notice a good response then you can start messing with 1/4 turns. 2. Check the pop off pressure (there are threads here that cover this), perhaps the guy that rebuilt them used too soft a spring so too much fuel is getting in there bogging you down. You will prob also need to adjust your idle as you adjust the low speed screw as well. I had a difficult time dialing in my keihins, luckily you only have 1.
    The other condition you could have is a lean one, as Bryan said pull the choke as it is bogging down if it start to take off you are lean (because the choke reduces the air going in therefore more fuel in the mix). That being the case turn the low speed screws out, opposite to the above.

  8. #8
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    accl pump not primed or needle arm height isn't set.

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Idle RPM in the water should be right around 1350 RPM.

    Out of the water idle RPM will be about double, give or take.

    Wide open throttle RPM should be well over 6000 RPM, more like 6300+ RPM

    Not a speed demon perhaps, but with that light weight engine and tuned properly you will be amazed how much farther you can go on one Virage fuel tank compared to the Yamaha 1100.

  10. #10
    Polcat2000's Avatar
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    It does get a little better when I feather it..or at least I feel like it does... I guess I need to know what the steps are for factory settings... I could make sure they are correct and go from there.. It does smoke pretty good, but my experience with two strokes are with dirt bikes. I have only had it out once and with your help, my second time hopefully will work all the little bugs out of it.

    Which screw is the low speed and which is the idle? What are the bench settings? I will be able to adjust my turns from there.. My guess is its rich..but Id rather have rich than lean... less damage..lol

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