'86 vfr750 carb fix

Discussion in '1st & 2nd Generation 1983-1989' started by taps, Mar 18, 2012.

  1. taps

    taps New Member

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    I'll go with your set. Email sent.
     
  2. taps

    taps New Member

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    So carbs arrived from BluRoad (thanks for the fast shipping and fair price!), and I have them mostly cleaned. I did run into two minor things. One of the butterflies (on carb #1) was tweaked open a bit on one side. I was able to straighten it out with some funny pliers wrapped in paper towel. I think I have that sorted well enough. Second issue is jetting/slides. The jets/slides in the carbs I received have had a dynojet (or similar) kit installed. The hole in the slide has been enlarged, and the jets have been changed to 120s. Pilot is the factory 38. My original carbs have 122 mains and the same pilots. I know we warn against swapping around slides, but...

    Also, if I did go with my original jets/slides (however well that may or may not work), one of the main jets is substantially larger than the others...with the same markings.

    I think my answer is to put the carbs back together just as they came apart. Now weirdness with slide swapping, and then I'm not dealing with the oddball jet.

    What say you?
     
    Last edited: Mar 26, 2012
  3. squirrelman

    squirrelman Member

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    It's a mistake to assemble the carbs if you can see that the jets are not the same. Jets can have stock size marking but be drilled oversize. They're cheap, so replace it there's any doubt.
     
  4. taps

    taps New Member

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    Which is why I'm leaning towards the slides and jets from the new carbs. They are complete and matching from what I can tell. I'm just not real crazy about the drilled slides.
     
  5. squirrelman

    squirrelman Member

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    Drilled slides are OK if you're doing the full jet kit deal.

    If your main jets are not stamped with a star-like logo next to the size #, you have a jet kit setup, and all that stuff needs to stay togrether: adjustable needles, drilled slides, and jet kit mains.

    You could swap over stock jets, stock needles, and stock slides if you wanted cuz most jet kit installations on '86/'87 VFRs are useless and improve nothing.
     
  6. taps

    taps New Member

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    I'll plop it together tomorrow evening with the parts from the new carb. They are certainly from a kit as the lack of a K on the jets are what got me looking at the slides. Who knows - maybe I'll like it? Now that I have new mounting boots, pulling the carbs isn't such a horrendous ordeal if I want to go with something else down the line.
     
  7. BluRoad

    BluRoad New Member

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    Taps, I didn't realize the slides had been modified, 'cause those are OEM needles. I think someone's been playing carb tuner.... Personally, I'd recommend fresh stock mains and fresh #40 lo-speed jets, along with the modified slides with stock needles, pilots out 2 turns and see what you've got. BTW, you should be aware that the DynoJet kits label their jets with a different numbering system than OEM, so if those mains are, in fact, from a kit, they may not be #120 at all.

    As far as jet kits being useless, here's my actual experience: I've had three different intake/exhaust setups on '86 750s. Stock jetting (with the addition of #40 lo-speed jets and 2 turns out on the pilot) works well with stock and with either the intake or exhaust modified. When both are modded a DynoJet kit will definitely benefit the power delivery (seat-of-the-pants). Having said that I do think the large main jets in the kit are excessive and provide unnecessarily rich jetting, though my gas mileage doesn't support this feeling. This season I plan to dyno my current bike and see, once and for all, what the effect really is. It has a Yosh slip-on and K&N filter, but otherwise stock. As I said, my seat-of-the-pants dyno indicates greater mid-range torque and harder pull up top compared to the '87 700 sitting next to it and what I recall from my previous 750s. Just my 2 cents.

    Let us know what you come up with.
     
  8. taps

    taps New Member

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    And where is the preferred place to get jets (in stock)? I looked at rocky mountain, and they show two (I think) different jets, and I don't have the jets at hand to measure to make sure I get some that will fit the carb.
     
  9. BluRoad

    BluRoad New Member

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    Well, I get mine at a local motorcycle aftermarket shop, and he gets them from the Parts Unlimited catalog, as I recall. For more money and time, my favorite online supplier is Dillon Bros, aka OEM Parts. I suppose any Asian m/c dealer can get whatever you need, also.
     
  10. taps

    taps New Member

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    So she is on the road again. I popped her together with the complete setup from the new to me carbs, and she seems to be doing okay with no dead spots. I'm still waiting on my carbtune to show up from england, but after a bench sync, it is close enough for a little test riding. I was not going to drive it just yet, then I decided to ride it Friday to work. Good times. Thanks for all the help!
     
  11. taps

    taps New Member

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    Well, the bike made the 200 mile round trip to my girl's house without incident. The Goldwing came out of the garage for the ride to work tomorrow. It is hard to find a compelling reason to ride that one when everything else is much more fun. Thanks again!
     
  12. taps

    taps New Member

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    And carbs were synched this evening. I did a quick run south of town, and she is much smoother with everything set correctly. I'm looking forward to a little riding this week before I head to Houston again this weekend (but that will be in one of the trucks :frown:). I know every new bike is the favorite for a bit, but I'm thinking this will be my daily commuter for the most part.
     
  13. JasonWW

    JasonWW New Member

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    Wow, I had to make sure this wasn't my bike. I had the exact same 2 issues. I succesfully found the brass part from another carb and fitted it into the hole. It was a very snug fit and I had to tap it into place with a hammer.

    Some big washers on the side bolt holds things together just fine.
     

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  14. Jobiwan

    Jobiwan New Member

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    How hard was the Kwaka front end sub?

    Saw a guy up north had made his '86 VFR700 into a streetfighter with Kwaka front and rear and loved the idea of more modern suspension, tyre choice. but especially retaining the tri-spoke wheel look!
     
  15. JasonWW

    JasonWW New Member

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    it was about usual I guess. I extended the kawa steering stem to fit the taller Honda neck. I also had to add a thin sleeve to fit the lower bearing. Those were the 2 main fabrication jobs. Generally speaking, newer model forks are going to be shorter, so I had to convert to traditional handle bars. Newer forks are also gonna add extra trail, so having the front a bit lower is actually a good thing as it reduces trail. The small amount of extra trail I have just adds stability and feels good.

    Going to beefy forks that are cartridge style is a big step up in handling, ride quality and stability. Plus the radial tire is an improvement as well.

    I had the internals of the stock rear shock changed out and that helped the rear.

    If you want to upgrade front and rear and want 3 spoke, matching rims I'd look at Suzuki parts. I've seen GSXR parts swapped without swingarm mods. find a good rear wheel that will fit the stock swingarm and then get the front.

    I started with the front and then couldn't get a matching rear wheel unless I did swingarm mods. That's okay though. I plan to cut the swingarm ends off and weld in billet cnc pieces. It allows for my wider rear wheel, plus I can stretch the swingarm a few more inches.
     
  16. Jobiwan

    Jobiwan New Member

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    Thanks for the reply :)

    Only realised after posting how old the thread was!

    Been looking at wheels from a Suzuki SV650 as a possibility - will have to research further.

    Again... thanks.
     
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