1986 Honda VFR750F

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

  1. michael

    michael Administrator Staff Member

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    Model: 1986 Honda VFR750F

    ENGINE
    Type: 748 cc, V4, 4-stroke
    Cooling: Liquid
    Bore x Stroke: 70.0 x 48.6 mm (2.8 x 1.9 inches)
    Compression Ratio: 10.5:1
    Power: 106.00 HP (77.4 kW)) @ 10500 RPM
    Transmission: 6 speed

    WHEELS
    Front Tire: 110/90-16
    Rear Tire: 130/80-18
    Front Brakes: Dual disc
    Rear Brakes: Single disc

    DIMENSIONS
    Wheelbase: 1480 mm
    Fuel Capacity: 20.00 litres (5.28 gallons)
    Dry Weight: 215.9 kg (476 lb)

    Original List Price: $5,287 US

    DESCRIPTION
    Major upgrade. Alloy beam style frame, 2.5x16" front wheel, 3.5x18 rear wheel, full fairing, Seat extends or wraps around tank slightly, Single rear shock w/ 2 sided Alloy swingarm, 180x crank, lighter pistons, connecting rods and valve train, gear driven cams, 4/2 exhaust, "Goldish" Cast engine covers looked trick. U.S. Colors were white w/red & blue stripes (R/W/B), Europe got all white or white with a large red stripe through the mid section and on the front fender w/gold pinstripes on the edges of the red. This model dropped 49 pounds off the (VF700/750F) weight at 215.9 kg (476 lbs). Honda claimed 105 Hp.

    The weakest part of the package were the 37mm forks with wimpy springs. The forks still had TRAC mechanical anti-dive mechanisms. This bike needed a fork brace and progressive springs before it left the showroom. Brakes are now "gold" painted instead of black.

    Typically it had about a $1,000 price penalty for the extra 50cc's. A $4k (USD) engine race kit was available from HRC which included a Titanium exhaust system.
     
  2. the-chauffeur

    the-chauffeur New Member

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    The 1st/2nd generation models in the UK ran from 1986-9 and the year of manufacture carried a different F suffix to aid identification:

    1986 - VFR750(FG)
    1987 - VFR750(FH)
    1988 - VFR750(FJ)
    1989 - VFR750(FK)

    All of these models have twin arm swingarms (the change to single sided happened in 1990 with the FL models). Michael's comments above relate to the FG/H models - the changes made in the first two years of production were relatively minor. And FG/H official dry weight was 199kg.

    Changes to the FJ/K models include:

    - internal engine modifications (increased valve sizes) and minor fuelling system (carb) changes. The weight of the FJ/K models increased to 203kg and while total power output/top speed remained the same, torque and bhp readings/curves changed due to the engine upgrades

    - external changes include 17" front (110/80 V17) and rear (140/80 V17) wheels, 41mm forks without anti-dive adjuster, flush fitting (faired-in style) front indicators, 4-piece front fairing panels (previously 3), adjustable windscreen, modified subframe with alloy footrest hangers

    - instruments/electricals updated to include a fuel guage and clock, together with a sidestand light (with the associated switch in the loom)

    - exhaust system redesigned with collector box. The centre stand of the FJ/FK was modified to fit over the pipes which ran along different lines to the FG/FH models

    The ignition system was also upgraded at some point after the first year, but depending on the source material you read, it was either available on FH or FJ models.



    - Additional information -

    From (bitter) experience, I've found a number of parts that many owners believe are interchangeable between the older models (FG/H/J/K) are very definitely not.

    I've got an FH, but don't like the wierd wheel sizes (16" front / 18" rear) so I decided to swap them for the later model wheels (17" both ends). I was told by a number of people that the front wheel would swap straight in. So I bought new wheels, only to find that there was no way the front would fit. So began the project to change the entire front end.

    FG/H forks are 37mm. FJ/K are 41mm. So the following are not interchangeable:

    - Front wheel
    - Forks (and fork internals)
    - Front spindle (FJ/K is about 8-10mm longer than FG/H)
    - Front wheel spacers
    - Upper and lower yokes
    - Speedo drive
    - Handlebars (also need to be drilled for resited switchgear)
    - Front brake discs
    - Left hand brake caliper and mount
    - Mudguard (nope - it's not interchangeable)
    - Top cowl
    - Side fairing panels

    The engines are also different, which causes problems with electrics if you're looking doing things like switching the clocks. Apart from the obvious colour changes between the dials - FG/H dials had white text and marker points; FJ/K were orange - the electrics changed between FG, FH and FJ (each one is different). The rewiring needed to update the FG/H is not straightforward - in addition, the tacho on the FJ/K models show that the engine revs to 13k rpm - at least 1,000rpm more than the older models. Because the FJ/K models had two circuits not found on the FG/H - including a sidestand cut-out circuit - the CDI units are different. Without an FJ/K CDI unit, rewiring the later tacho to work on an FG/H model is a very, very tricky job (read prohibitive).

    To compound matters, although the different clocks sort of fit into each of the four models, there are some small but annoying issues that you need to be aware of before making the switch. By far the easiest mod is to change the speedo dial and the guages/warning light section - that way, the left and right facias are orange, leaving the tacho with a white face by day and a matching orange glow by night. More importantly, these mods don't require any tricky rewiring (although you will need to change the fuel sender - see below). However, there is a fitting problem relating to the design of the rear of the speedo unit - a change in the manufacturing process between the FH and FJ meant that the drive unit in the back of the speedo changed shape. The result is that the joint where the speedo cable goes into the back of the FJ/K unit prevents the whole arrangement fitting into the front subframe (headlight mount) of the FG/H.

    The bracket shape only changed very subtly between the FH and FJ models to allow space for the speedo design changes, but it's enough to stop the two units being physically interchangeable. Unfortunately, the only way to get the FJ/K speedo to fit into the FG/H mount is to cut a corner section out of the bracket - but as it's tubular steel, that kind of modification will seriously weaken the structural integrity of the bracket as a whole. And as the FJ/K models had faired-in indicators (and not stalk mounted), there is no place to attach stalk mounts to the subframe. If you decide to go down this route - grafting the front subframe from an FJ/K onto an FG/H, you'll need to buy aftermarket indicators that attach to the fairings. One other thing to watch out for with the subframe change is that the FJ/K subframe sits very slightly higher on the bike than the FG/H (probably to give an extra few mm for the 4-piece fairing joints). If you have a 3-piece FG/H front fairing, this will have the effect of pulling the fixing points of the fairing away from their mounts. It's not particularly noticeable, but it helps to loosen the various stalks mounted on the main chassis, tighten the fairing-to-stalk fasteners, and then tighten the stalk mounts.

    As far as the bodywork is concerned, the top cowl of the FG/H models has different mounts to those on the FJ/K models. The top edges of the FG/H side panels fit up and behind the top cowl - the FJ/K side panels mount over the top of the top cowl. In other words, they're not interchangeable. Additionally, the fairing inners changed between the FH and FJ models - the earlier ones are very dark blue, whereas the later versions were dark grey/black - and fairing lowers came in from the FJ onwards.

    Although the shape of the fuel tanks did not change between the FG-FK models, the fuel senders within the petrol tanks did. The FG/H models used a static sensor on a stick - there was only a low fuel warning light on the dash and not a gauge. On the FJ/K models, the dash had a variable gauge, so the fuel sender in the tank was changed to a float-on-a-stick system that rose and fell with the fuel level.

    Sadly, the faired-in front indicators (which look very attractive on the FJ/K) cannot be fitted to the FG/H without some very major - again to the point of being prohibitive - plastics modification. On the upside, the larger, adjustable screen from the FJ/K models can be fitted to the FG/H with some minor (and largely unnoticeable) modifications.

    The rear subframes are pretty much interchangeable, but the rear hangers and footrests on the FJ/K models bolt on, as opposed to being part of the frame - and depending on what exhaust is on the bike, the mounts may not line up. The later rear mudguard is a slightly different shape to take account of the change to the pillion footpegs, which also have built-in luggage hooks - meaning that the later models lost the pannier rails.

    One variable I can't conclusively comment on right now is the rear shock. Both the FG/H and FJ/K model shock units were made by Showa and visually they look the same, although I haven't been able to do a side-by-side comparison yet. There is some conflicting information about which shocks (if any of the four) are interchangeable - it seems the FH shock is 270mm from eye to eye, whereas the FJ shock is 290mm. Keny's note below is also very helpful. On the flipside, there are a couple of factors that suggest the shocks are identical - FH and FJ shocks bear the same Showa part number (ML7-921) and when you look at aftermarket suppliers, they quote the same part number for all four years. Wierdness.

    Some other minor stupid stuff needs alteration too, like the length of the seat lock release catch - the FG/H catch is too long for the later models. In addition, the rear indicators are different shapes, with the FG/H being on stalks and the FJ/K curving out from the bodywork. Not a big difference, but it does mean that the mounting points on the respective subframes are different shapes.
     
    Last edited: May 4, 2007
    Shannon and squirrelman like this.
  3. keny

    keny New Member

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    A comment on the rear shock. The FG has a shorter shock that the FH. Dont know about FJ/K. The FG has a differnet rate spring and linkage rate than the FH. I have a Hagon shock listed for the FG/H and its much stiffer than the stock. No risk for botomings 2 up rideing as before.
     
  4. keny

    keny New Member

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    Some more specific info. 86 vfr750f shock is 10,63 long (inch)(270mm) and 87 vfr750f has a 11,00 long shock(~280mm). the 87 has 25% softer spring than the 86. the linkage is also diffrent in rate.
     
    Last edited: Apr 10, 2008
  5. crocodilemick

    crocodilemick New Member

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    Not sure if anyones interested, but I couldnt find this info anywhere else so thought I'd post for the next person (thanks to Keith in the UK for digging out his Official Honda Service manual and emailing me):

    Valve clearances for VFR750F models G-K:

    COLD ENGINE
    Inlet Valves 0.13mm (0.005")
    Exhaust Valves 0.20mm (0.007")
     
  6. terrinitup

    terrinitup New Member

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    Hi All - I'm new to this site so not too sure who will read this message.
    I have a 86' VFR750F. My sister's (asshole) boyfriend decided to adjust my chain while I was over for a visit... NOT COOL! It now makes a terrible noise while riding. I don't know what he did, but I do know that the tire is now at an angle it shouldn't be, and the sproket looks like it too is pointing another direction. The wheel itself is also off center. WHAT THE HELL ? I want to kill the guy! So please what exactly can I do to fix this problem...... I do work on my own shit... I have two dirt bikes, one of them is my 9 yr olds. CRF230 and Kawaski65. I had to rebuild his top end since he blew the piston.. I did it myself without a manual.. Not too bad... :) lol
    Any feed back about my VFR would be appreciated!!
    Terrinitup Thanks All Viewers!
     
  7. keny

    keny New Member

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    A litle more info on shock lenght for the first and second gen VFRs.
    WP has listed a shock for these,and the shocks are height adjstable +- 5mm.
    the leght for the 86-87 is 269 to 279mm
    for the 88-89 278 to 288mm
     
  8. keny

    keny New Member

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    One more diffrent betwen 86 and 87 found. Electrical. As the ignision system is diffrent the picup for taco is diffrent nad that do that clocks from a 86 to a 87 dont fit even they look identical (accept us style round) and plug in straingt, the rpm will not be right.
     
  9. BiKenG

    BiKenG New Member

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    There is still some confusion around this and although I cannot be definitive about the changes, having worked for Honda UK, I can comment on their normal model and update cycle.

    Any model will normally run for 4 years before any major changes with possibly a minor update at the 2 year mark. Each of those 2 years would then involve very few very minor mods at the 1 year point, usually limited to just colour options, if that. Essentially the FG and FH are the same bike. Likewise the FJ and FK are the same bike. Those 2 variations however are basically the same, but with differences as being discussed here. After 4 years, expect a new model. So the Gen 3 in 1990, while ostensibly still a VFR750, it was markedly different to what went before. Likewise the Gen 3 - 4 changes etc. The Gen 5 probably had the most similar update cycle as that had some significant changes in the middle at the 2 year point.

    So, with the above in mind, I would be extremely surprised if Honda changed the length of the rear shock between the FG and the FH models, and likewise between the FJ and the FK. However it may well have changed between the FG/FH and the FJ/FK, i.e. for the '88 model year. If you read anything to the contrary on any suppliers web site, I would suspect their data.
     
  10. Captain 80s

    Captain 80s Member

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    ZOMBIE THREAD ALERT!
     
  11. Captain 80s

    Captain 80s Member

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    And, by the way, the 86 FG and the 87 FH are different shocks. 87 is 10mm longer and has a slightly different design. They did some valving changes and changed the dimensions of the "Arm Assembly". The "Rod Assembly" is a different design but has the same dimensions.
     
  12. BiKenG

    BiKenG New Member

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    Well if you say so, but I'd be very surprised. Changes of that magnitude are not incorporated at the 1 year mark. Unfortunately I was no longer running the Training Schools when the VFR was launched so I have no direct experience.
     
  13. Captain 80s

    Captain 80s Member

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    Don't be surprised. Be corrected. It is so.
     
  14. BiKenG

    BiKenG New Member

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    Well, thank you for that. As you point out, it appears there was a change after one year, that then continued for the next 3. So for the first VFR750, they obviously felt the need to bring in the shock change a year early after just one year.

    However, I stand by what I said, that is not a normal update cycle. A change that significant is unusual after just one year. I didn't say impossible, but my experience working with Honda indicates that as unusual and so yes, I am surprised. Thank you so much for pointing that out so eloquently.
     
  15. Captain 80s

    Captain 80s Member

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    Sorry, wasn't trying to be that harsh, just succinct. Actually something had to happen after 87 too. The bike went from 18"/16" wheel combo to 17/17 in 1988. So there was some additional changes somewhere in the rear suspension to compensate.
     
  16. BiKenG

    BiKenG New Member

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    Indeed, but the wheel change and many other significant changes took place at the normal 2 years, yet the shock was changed after just the one year. I wouldn't be so surprised if it was just some minor revision, but they changed the length? As I said, not impossible (obviously :)), but it was a deviation from their normal product update cycle.

    Having said that, the VF1000R was also changed internally a fair bit after the first year. Many of the engine internals were changed, although many (like cam gear train) did not, so they were revisions rather than any major re-structuring.

    I rather think it was down to the problems they had been experiencing in the recent past and wanted to be sure they'd quashed them and so were prepared to make more changes than would normally be expected, at more frequent intervals to ensure they kept on top of it. As the new models proved themselves and became accepted, they were able to revert back to the more usual update cycle. This is however, just my interpretation of it. I have no direct inside information on that.

    But back to specifics, the RC24 frame part number changed during '86 and then remained the same. Certainly it did NOT change from '87 - '88 which is when you might have expected it to change. I've not been able to determine if that actually co-incided with the shock change. It appears not according to the parts list and I have been told the frames are ALL the same, no change to rake etc (unconfirmed), so the frame change might have been very minor. The subframe however also changed after 1 year, but then again at 2 years. I believe that for the last 2 years the pillion footrest brackets were bolt-on which explains that number change. As I said above, I think this was a clear attempt to ensure everything was right and stayed right.

    I'm still puzzled about the VF1000R though. At this stage, I do not believe there was ever a chain cam drive VF1000R. Not only am I unaware of any such thing, it really doesn't make sense. The VF1000R was specifically the race replica (at the time) with the gear driven cams of the earlier racers. I would be very surprised indeed to find I'm wrong about that.

    I can also find no evidence of any major dimensional changes to the engine. There were some internal mods to camshaft bearings and other items, but none which indicate a significant external size difference. Having said that, the bike did tend to run hot and the above changes did include the heads so maybe they also added some additional external finning to help cool and that makes the '85 on engine a bit fatter at the top? I'm surmising again, but I'd love to get an '84 and '85/'86 side by side and measure them. Anyone got both engines?
     
  17. Captain 80s

    Captain 80s Member

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    Not minor. Shock was redesigned and a different length. Additionally another component of the suspension was redesigned as well to compensate and retain the ride height. I have both sets sitting in my shop.

    When doing 17" wheel conversions you can compensate for ride height by using the alternative component. An 87 shock on a 86. Or the 86 linkage piece on a 87 . Does the trick if you don't have an aftermarket shock with separate ride height adjustment. I've done both and used an 87 linkage piece with a modified CBR Fox TC on a 86 to compensate for the length (as short as I could get it without major surgery on the shock).
     
  18. BiKenG

    BiKenG New Member

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    Ah, but ignoring ride heights and shock lengths, could you get a VF1000[F|R] motor into an RC24?
     
  19. Fastdruid

    Fastdruid New Member

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    The change to the frame is in construction not rake/trail etc.

    The 86 frame consisted of something like 8 or so major cast parts, this was then reduced to something like 6 or so as the rear section was changed from a welded construction to a single casting. You can easily tell the difference if you look at the sides above the swingarm pivot (as well as below but that's trickier to spot).

    '86 Frame
    [​IMG]

    '87+ Frame
    [​IMG]
     
  20. BiKenG

    BiKenG New Member

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    Interesting. That explains it. Thanks.

    But would still like to know if a VF1000 engine can be made to fit?
     
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