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Bench Syncing 1988 FJ carbs

Discussion in 'RC24' started by RockvegasVFR, Nov 14, 2017 at 11:48 AM.

  1. RockvegasVFR

    RockvegasVFR Registered User

    Hello All,
    My RC24 is an '88FJ, Australian delivery, and I'm looking for advice on bench syncing the carbs prior to refitting them for a final check with my Carbtune kit. . She was running fine, when I decided to get my valve clearances checked as they had not been done in the 2 years I've owned the bike. Given how difficult it is to access the valve adjusters I got the local Honda dealer to do this, and asked them to check the carb sync whilst they were at it. All checked out ok, except the dealer advised that I had a crack in one of the plastic fuel tubes between the carbs. I had not noticed a leak prior to this, however in the interest of safety they disconnected the fuel and advised that a replacement part would take some time to arrive if available. I advised that, given the age of the whole tube set, I preferred order a set of aluminium tubes from the US that I'd heard good reports on. So the bike was transported home.
    Have pulled the carbs, and separated them just enough to install the new rails - i.e the adjustment gear on each carb was left intact - with the choke mechanism being the only bits that needed to be re-joined. All back together now with cleaned jets and clean float bowls installed with new o rings. The air screws have been left untouched behind their covers. Have run some fuel to ensure there are no leaks (fuel lines replaced prior to the current issues).

    My references for the carb work have been the Honda RC24 shop manual, plus a fairly comprehensive carb overhaul resource I found on the VFR World forum. I have 2 questions re bench syncing prior to installation and searches of this forum haven't indicated any earlier answers re this. Both references advise aligning the butterfly valve relative to the "by-pass hole". Honda advise to adjustment to the edge of the hole (which edge is not specified), whilst the other source says leave half of the hole visible. On my carbs, though, there are 3 pin holes (pictured) so I'm unsure which one the butterfly should be aligned to (see picture attached).

    The second issue is that carbs 2 (adjusted by idle screw) & 4 have a fair bit of adjustment and can both be adjusted to the bottom of the outside hole, whilst 1 & 3 seem to have less and wont adjust beyond the middle hole. Is this normal or have I missed something? All the springs are in place as I found them - the manual and the Honda parts diagram are not very illuminating if you were starting assembly of the linkage from scratch though.
    Thanks in advance for your advice - the annual Xmas Toy Run is coming up in a fortnight, and I'm missing riding my old girl. Justin

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  2. saintrommel

    saintrommel saintrommel Club Sponsor

    I made the mistake of thinking I could clean the carb airways without removing the air screws and so had to do them twice well three times actually but we won't go into that ,had them balanced afterwards and nowall good.

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