1990 VFR750 Carb Issues

Discussion in 'Mechanics Garage' started by Hingley, Feb 24, 2019.

  1. Hingley

    Hingley New Member

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    Hello everyone, I need some 3rd Gen Carb guidance.
    A couple of years ago I bought my first modern bike [ for me} a low mileage 1990 VFR [ran great ] and figured I would go over it during the winter to make sure she was 100% and be riding in the spring of 2017. Well life threw me a twist and I put off the servicing until now. I have all the brakes redone with new dot 4, clutch too, front forks rebuilt with new oil, tapered bearings etc. I was at the point today I thought I would fire her up, well after a long process of getting her to run on all four cylinders, [ it took a lot of messing with the fuel supply to get her to pick up the fuel and when she did she for a while only wanted to run on the back two cylinders. So after what seemed forever she was running on all four but when I started to feed her throttle she started to spill fuel from the carbs { the bowls I think ].
    So the questions I have is,
    Will the gaskets soak up the fuel, swell and seal themselves?
    With all your guys experiences with VFR carbs does it sound right that it is the bowl gaskets that are leaking?
    Is there a gas product I can add to the fuel to help clean the old fuel crap out of her?
    Or do you think { I hate the thoughts of this one] do I have to suck it up and pull the carbs for cleaning and rebuild
    If a rebuild is the end result where is the best source of carb parts, Honda, E Bay? are the carb kits on E Bay any good?
    Thanks in advance for any advice you can give, until now I have played with only 1970's Honda's and I must say I am in the dark when it comes to fuel pumps and complex carbs that are buried under air box's
     
  2. bk94si

    bk94si New Member

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    I think a rebuild is in order. Clean jets and new float valves.
     
  3. squirrelman

    squirrelman Member

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    yes, after 1 or 2 days the bowl gaskets may swell and seal again. you'll need to keep gas in the bowls by pushing the starter button occasionally.
     
  4. Hingley

    Hingley New Member

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    P2250963.JPG P2250965.JPG I am interested in seeing if I can get the carb rubbers to swell and seal. Today I got it going but it took many cycles with the key on and off followed by the starter, I guess the pump was getting primed that way, once it fired up it was a lot easier to start. It did start to leak fuel but it took longer today. attached are a couple of pics as she looks today
    What are peoples thoughts on the best and cheapest place to get carb gaskets etc
     
  5. Hingley

    Hingley New Member

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    Well Squirrel man, you were right on the money

    I let the carbs soak up the fuel for a few days and the bowl gaskets swelled up and it looks like they are not leaking anymore.
    I have been running the bike a few times over the past couple of days and it fires up right away, it does need to be really warmed up before she will idle at 1200,
    without blurping the throttle and I find if I hold her at 4 grand I think I hear a flutter so I am guessing she has some old deposits in the carbs.

    Has anyone found a gas additive product that will help clean out the carbs or is it time to shut up and pull the carbs.
    If it is time to pull the carbs and clean them, are there any links to the process?
    Are the Honda carb parts the way to go or is there good aftermarket kits?
     
  6. squirrelman

    squirrelman Member

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    the only parts that might need replacing are float bowl gaskets, float needles, fuel tube O-rings, or mounting boots; other parts just need a good cleaning.

    after a 2-3 minute warm up you should be able to take off any choke, and the engine should take throttle, not drop below the 1200 rpm idle speed when gassing it.
     
    Last edited: Mar 3, 2019
  7. Hingley

    Hingley New Member

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    Once again you are on the money
    Being a Honda she is cold blooded, once it is warmed up to the point of the temp gauge starting to move you can back off the choke and she will idle at
    1200 +-. If you rev it to 4000rpm it responds well. if you hold it at 4000rpm that is when you will hear a little blurp coming out of the Yosh exhaust
     
  8. Hingley

    Hingley New Member

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    So What are the thoughts on sourcing Carb parts ( gaskets,intake manifolds etc ) for the 3rd Gen VFR's
    Are the aftermarket kits I see on Ebay good quality or does a person have to use the original Honda parts
    I have done some checking here in the frozen north and I can tell you that you guys are a lot better off then we are for Honda pricing
    I just found on the webb that All Balls are selling a carb kit for the 1990-1993 VFR750, has anyone used it yet, the dealers up here do not even have a listing for it, figures
    Thanks
     
  9. BluRoad

    BluRoad New Member

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    For some potential guidance you may want to visit my website's "Maintenance" page. Your carbs need cleaning and some new gaskets. They will leak again. It's a great learning opportunity.
    V4Dreams.com
    joe.nelson@ymail.com
     
  10. scottbott

    scottbott Insider

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    lots of interesting stuff on your website, never heard of it before, thanks for the link
     
  11. penak

    penak New Member

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    never experienced it. but this is a very interesting discussion to follow[​IMG]
     
  12. Hingley

    Hingley New Member

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    This is without a doubt one of the most informative sites ( V4Dreams.com ) I have ever seen, I would not have ever found it without
    your guidance Joe, Thanks
    Reading the articles gives me the confidence to dig out to the carbs, the other articles you have posted are a great reference for future work
    Once I got organized I will be ordering a few components from you

    Joe, While I think of it, as you can see there is a full Yosh exhaust system on the bike, I do not know yet but I am betting the bike as not been rejetted
    If it has not been rejetted have you found that these bikes ( 1990-1993 VFR's ) need to be rejetted with aftermarket exhausts. I have a 1989 Honda CB1 with an aftermarket exhaust can and it runs and burns fine with stock jetting
     

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