1986 Honda VFR750F

Discussion in 'Specifications' started by michael, Jan 29, 2006.

  1. BiKenG

    BiKenG New Member

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    It's the wrong way up. Honda have not, to my knowledge, made an upside down rear Swing-Arm on a road bike. I think one of the Yamaha R1s did though. (In fact it's the R1 with underseat exhausts, around 2012.)

    However, realistically, might as well put this project on the back burner until I know more about any new sensibly priced V4 SuperBike from Honda.


    Of more pressing concern would be RC46 engine in RC24 frame and RC24 engine in RC36 frame.
     
    Last edited: Aug 5, 2019
  2. rcsocket

    rcsocket New Member

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    Replacing gen2 instruments with gen3

    RC24 Gen2 instruments are now rare but lots of RC36 Gen3 are to be found.
    Fitment is essentially plug and play apart from the following-
    So here is what you need to do the swap.
    Obtain from Gen3
    instrument cluster, sprocket cover, clutch push rod, speedo drive, coupler and cable.
    Gen3 speedo is driven from gearbox mainshaft not F/wheel as on Gen2
    You need to space out the sprocket retaining bolt by 10mm (longer bolt)
    Allowing for tyre size 140/80 vs 170/60 and sprockets 16/45 vs 16/43
    the speedo will indicate 1.8% fast on the Gen2. If however the rear sprocket
    on the Gen2 is changed to 44t speedo error will now be 0.4% slow.

    The Gen3 tacho has different drive electronics to the Gen2 but the
    electronic module on the back of the tachos are interchangeable
    Remove the modual from the back of the Gen2 tacho and plug it into
    the Gen3. The two meter wires need to be soldered.
    Note- 3 connects to the Gen2 tacho so either swap harness or provide
    brown/black feed. The middle connect hole needs to be drilled and the wires
    Gen2 are in a different order to Gen3.

    Replacing the illumination bulbs with Leds really brightens the display.
    I used a strip of rubber cut from an old inner tube and attached with
    double side sticky tape across the top of the instruments to mask
    the back side from the screen.
     
    Last edited: May 3, 2020
  3. keny

    keny New Member

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    After years whit to many bikes, finally a 1986 VFR750F in my garage again (whit a few other) and has been searching again for shock for it, whit a wheel mod, and gone thro diffrent offerings,
    YSS offers same shock for a 4 years the RC24 made, its 275mm long.
    Wilbers Shocks offers correct lengt for year, 270mm for 86, 280mm for 87-89
     
    Last edited: Jan 10, 2024
  4. Fastdruid

    Fastdruid New Member

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    The linkage is different between the 86 and 87-89 as well (the 86 has a much softer spring and softer damping). So the YSS is either going to be a compromise on all fronts or unsuitable for one or the other.

    I'd assume that Wilbers if they offer the different lengths also has the correct damping rate and stiffer spring to match the different linkage.

    Of course even a "totally wrong" YSS may be a significant improvement on what is a 34-38 year old original shock!
     
  5. keny

    keny New Member

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    I emailed Bitubo for messurments of there shocks and got a anwser really fast.
    They however offer 2 shocks, but one for 86-87, that is for 86 only actually, its 270mm long, 45mm storke and a 16kg/mm spring
    the offering for 88-89 is 279,5mm long, same 45mm stroke and a 19,4kg/mm spring
    the piston position is also different witch means different damping.
     
    Last edited: Jan 10, 2024
  6. keny

    keny New Member

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    The YSS has a 56-180-150 spring, that is 56mm inner diameter, 150mm long and spring rate 180 N/mm that is ~18,35 kg/mm
     
  7. Captain 80s

    Captain 80s Member

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    I don't think any of us can say all of our bikes are perfectly set up without any compromises. I can confidently say that an 87 shock mounted in an 86 (linkage) works pretty fucking good. Most Hondas are under-sprung and over-damped, and I don't think the 86 is any exception. The 86 responds nicely to the stiffer 87 shock. And while the 87 shock is not that great to begin with, it is a better design than the 86. The 87 has separate damping circuits for compression and rebound, where the 86 uses the same circuit for both.

    I can also confidently say a YSS performs really nice in an 86. If I were to install one in an 87, I would personally probably install the 86 linkage to take advantage of some additional ride height. Yes, I know the ratios are different, but it just plain works nicely.
     
    Last edited: Jan 10, 2024
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  8. Fastdruid

    Fastdruid New Member

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    So stiffer than the stock 87-89 then and a *lot* stiffer than the 86.
    (Ohlins recommend 110N/mm for the 86 and 160N/mm for the rest).
     
  9. Fastdruid

    Fastdruid New Member

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    They are massively under-sprung as stock, I'm not 100% sure on my 88 but racetech say the 86 had 0.5Kg/mm fork springs in... I stuck 0.95Kg/mm in!

    So yeah, I can see that despite "technically" being massively over sprung vs the original it could actually work well.
     
  10. Captain 80s

    Captain 80s Member

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    YSS as delivered are sprung a bit on the high side I have found, but in use they have all been great and I wouldn't have wanted something softer. I am able to get good static/race sag numbers. If you order from certain vendors, they will install the spring of your choice for an additional fee. I don't think it's exorbitant.

    biketyresuk on eBay is the store front for the UK YSS R&D, Firefox Racing.
     
  11. RogueRC24

    RogueRC24 Member

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    General shock info from my '88 (VIN ending in 00100) FJ build. Penske, original swing arm and linkage, CBR600F2 rear wheel.

    Penske:
    "We have 2 specs, first spec is 279mm e-e and the second spec is 290mm e-e."
    I went with the 290mm.
    Model:
    PS-8983 REMOTE, double adjust (low speed comp/rebound), remote reservoir,
    290 e-e for this shock.

    In case anyone wanted more data.
    Big Red.JPG
     
    Last edited: Jan 10, 2024
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  12. Fastdruid

    Fastdruid New Member

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    The lack of ride height options plus the generic 86-89 puts me off them (although again, undoubtedly better than the 34 year old shock in there). I'm going to go with a Nitron in mine from PDQ (along with the '86 linkage). The '86 linkage as it both gives more rear height *and* you can use a longer shock. I need to make up dropping the rear due to the wider but lower sidewall tyre and a bit more to steepen the rake/ reduce trail.
     
  13. Captain 80s

    Captain 80s Member

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    In this particular case, the ambiguity regarding valving is obviously present. I do know they work very good in an 86. And on every other one of my bikes that have them installed where Honda wasn't making changes every goddamn year, they have also been great. The value is there for sure, they are nice pieces.

    I have Ohlins, Nitron, Fox in other bikes, but I can't afford that level of shock in every one of my bikes. I do have a lot. YSS fills a need quite nicely. And on a couple bikes I did not want a remote res.
     
  14. Captain 80s

    Captain 80s Member

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    The 86 linkage is not both attributes, is it? Yes, it gives more ride height, but he 87 shock is longer than the 86, and the 87 linkage has it end up with the same ride height.

    So... the 87 piece actually lets you install a longer shock before reaching the swingarm limits. I had to this on the RC26 because my modified Fox was still very long, more than the 86 linkage could reasonably accommodate.
     
    Last edited: Jan 10, 2024
  15. Terry Smith

    Terry Smith Member

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    I can't comment on the YSS for the VFR but on my ST1300 shock, it had an adjustable length clevis so I can make the shock any length that I want (within reason). IMG_4639.JPEG
     
  16. Captain 80s

    Captain 80s Member

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    The YSS for the VFR is the ONLY YSS I have seen that does not have adjustable ride height. I don't know why.

    I have 6 YSS installed.
     
  17. Fastdruid

    Fastdruid New Member

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    Yes the 87 has a longer shock to account for the difference in linkage.

    The limit however is when the shock hits the swing arm, I'm informed by PDQ that the 86 can take a longer shock than the 87-89 *and* with that adds to the extra height from the linkage.

    I'll dig out what they had to say on the maximum lengths (obviously subject to exhaust clearance and individual shock choice as some may work better/ worse than others).

    EDIT: spring hits on full extension, there is about 5mm difference between them, linkage is about 3:1 so gives an extra 15mm on ride height over the later bike.
    Again, in theory and will depend on exact make of shock etc.
     
    Last edited: Jan 10, 2024
  18. Captain 80s

    Captain 80s Member

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    Ahh. I see what you're saying. For me, my Fox shock hitting anything was not the limiting factor with either linkage. The angle of the swingarm was extreme and I quite frankly didn't need that much ride height. As it is I can feel the chain riding over the top of the swingarm chain protector when coming to a stop.

    20180402_165713_resize.jpg

    Oh, and the Fox installed on this bike is ~300mm.

    IMAG1004.jpg
     
    Last edited: Jan 10, 2024
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  19. keny

    keny New Member

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    My TRX850 I buoght a YSS for when the orginal blew all oil out, it didn't have adjustable ride height as well, but performed good and was a few mm longer than orginal
     
  20. Captain 80s

    Captain 80s Member

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    I kinda think it's because of how short of a shock the VFR is. Is the TRX shock pretty short too?
     
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