(Below) I'll want to first install any parts which are more accessible with the carbs separated, so I begin with the air cut valve assemblies (Gen-3 and -4 only). First, I set the oval o-ring in place, flat side toward the carb body, then set the diaphragm in place, the small "needle" inserted into the carb body. I've treated the rubber with a light coating of Red Rubber Grease to soften and preserve the diaphragm. With the spring in place I press the cap straight downward, keeping the diaphragm centered, and hold it firmly while installing the first screw — a magnetized screwdriver tip really helps here. These are fiddly assemblies to install due to the firm, wobbly spring, so proceed carefully. Tighten both screws firmly and install the remaining three assemblies.
(click on images to enlarge)

(Below) Next I'll install the fuel mixture (pilot) screws and the enriching (choke) assemblies. I first assemble the mixture screw's spring, then washer, then o-ring and gently seat them fully, then back off 2 1/4 turns (2 1/2 for Gen-2) — this is a good general starting point; an additional quarter turn is a good idea for intake or exhaust modifications. For reference, turning out is more fuel, in is less. Note the black marker on the screwdriver blade; this helps me keep track of rotations.

Note the differing choke shafts and their placement. Assemble the shaft, spring and cap, installing into carbs #1 and 4, gently snugging the cap with a 14mm wrench or pliers. Installing #2 and 3 choke shafts is more involved, assuming you'd chosen to separate those carbs. This is covered in depth in a September 2025 Shop Blog post, "Separating Carburetors, The Easy Way."

(Below) I'll move on to slide/diaphragm installation next. I first need to install the plastic needle holder into the bottom of the slide (not applicable to Gen-2); this part goes in flat ears first — it's fiddly, but you'll know it's right when the tabs are flush into the bottom recesses (see last photo). I then install the jet needle, using a needle nose pliers and tilting upward to keep the washer on the needle, followed by the spring cap, snugged in place with an 8mm socket. Finally, test that the needle moves freely in & out (a few millimeters) with slight spring pressure.
Note: The Gen-4 slide design is very different, with its own assembly procedure; refer to the FSM.

(Below) Next, I'll fit the assembled slide/diaphragms into their bores. Slide an assembly into its bore, ensuring that the rubber perimeter ridge seats all the way around and the small tab is located correctly (photo 1). Also check that the jet needle has engaged its jet hole correctly (photo 2). I find that keeping the diaphragm raised and holding it with my left middle finger (photos 1 & 4) works best for the next step — insert the long spring, and push downward with the diaphragm cap to engage the cap's tiny raised dowels, all while holding the slide upward; if the cap doesn't seem to positively engage its dowels, try again till it does. It's important that the rubber diaphragm is fully seated in its groove around the perimeter. Holding the slide and cap stationary, install the four cap screws (photo 4); here I'm using an electric screwdriver which makes one-handed screwing easier. Then tighten the four screws (photo 5). Finally, test the slide action by pushing all the way upward and letting it fall on its own — there should be mild resistance going upward and a slight "whoosh" as the slide drops smoothly and gently all the way down to the closed position (photo 6). If you're not getting that action, consider rechecking the diaphragm fitment. If it feels good, proceed to the other three slide/diaphragms.

(Right) I find it easier to fit all four diaphragm caps and then go back and install any ancillary pieces, like the choke cable bracket on #4 carb, shown here. I'm more confident in having installed the diaphragms correctly when only having to deal with the bare screws and not their connecting parts. Here, I'm adding a new screw for the hold-down bracket (it was buggered up) — it's the same screw as the cap screws. Replacement screws are available on the "Products" page.

(Below) I'm now ready to install the fuel and vent lines. In the first photo, fire damage actually melted a hole in this vent tube but fortunately I had a spare on hand. If I hadn't had a spare I would have simply put two layers of heat shrink tubing over the area, as these vents will be open to the atmosphere so are not an airtight system. Next, I install fresh fuel tube o-rings and coat all the o-rings with Red Rubber Grease or similar.

I can't demonstrate the tubes' installation in photos, but after an appropriate amount of fumbling about you will eventually get all the tubes in their correct positions — you took photos, right? In any event, photo 3 below shows the correct routing (Gen-3). California-spec carbs have a slightly different-looking vent tube but it installs in the same relative position. On the Gen-3, the hose clip (photo 4) holds the fuel line from carbs #1/3.
NOTE: Gen-2: The choke rod assemblies are installed during the above exercise.
NOTE: For more reference photos of the various generations, see the Maintenance page, end of post #1.

(Right) With everything in place I like to carefully flip the carbs to the engine side and loosely install the center joining bracket which will help hold the tubes in place until I complete the next step: installing the plenum.
(Note: we need this bracket loose enough to allow the carb set to flex enough for the plenum to slip into place)

(Below) Here's some tips for preparing the metal plenum for a smooth install. In case you've lost track, on the Gen-2 and -3 this shark fin on the plenum goes between carbs #1 & 3 (photo 1).

I need to verify that all the dowel pins are in place by holding the plenum above the carbs and visually checking every hole has a corresponding pin; some will be in the carbs, some in the plenum (photo 2) — I didn't remove any dowels that were reluctant to remove as they are easily deformed if forced; just leave them in place during the rebuild process. But, to make them easier to slip into place, I clean any accumulated corrosion with a small Dremel wire brush and lubricant the dowels and their openings with a light oil (photos 3 & 4).

For carbs with funnels, like these, it may help if you set each funnel in place on the carb bodies, seeing how the tabs engage, then mark their orientation with a bit of tape or marker (photo 5), then loosely install into the plenum openings with your markers roughly oriented (photo 6). This will help with getting them lined up correctly when lowering the plenum into place.

(Below) Before lowering the plenum in place, verify that all the fuel/vent tubes and lines are still in place and that the carb-to-plenum o-rings are sitting correctly in their grooves. Then lower the plenum onto the dowels, get all four funnels into their slots (photo 1), and work the carbs as flush as possible by hand. Like fitting the fuel/vent lines, this is a juggling act but it can be done. Watch for the fuel/vent tubes to stay in place, they can slip out easily. There will likely be slight gaps between the carbs and plenum due to the tight fit of the dowels, but we'll address that as we snug the screws down.

After a few attempts, and with everything in place, install the plenum brass washers and screws, but just bottom the screws in place, don't force them down yet. When all the screws are bottomed, gently tighten them in an alternating sequence, looking to see that the carbs are gently lowering flush to the plenum — again, don't use force; if it's taking too much effort, something is out of line and causing a bind. I don't bend the washers' locking tabs at this point — I actually wait till the carbs are tested and tuned, just in case they would need to come apart; we don't want to bend those soft tangs more than necessary. NOTE: the washers are available from Honda.

With the carbs seated to the plenum, the carb set is now firmly held together. Flip it over and check that the throttle and choke linkages move freely (photos 3 & 4), if not, figure out why. Visually check that the fuel/vent tubes and lines are still in place, if not, remove the plenum and try again.

Next, I install the underside bracket (or tighten, if already in place). It is important that this bracket naturally lies flush with the carb surfaces (photo 5); we don't want to force the carbs into place with this bracket — if the bracket doesn't lie flush, something is not assembled properly. When all is right with your world, tighten the eight bracket screws (photo 6) and retest the throttle and choke linkages.

Gen-2 and -4, tighten the side screws or nuts.

(Below) Next I install the springs and choke rod assemblies. The two throttle shaft springs slip easily into place (photo 1); the larger between carbs 2 & 4, (Gen-4: between carbs 1 & 3). Next, the sync screws are inserted into the place. I try to make this easier by holding down the relevant butterfly with a finger (just enough to take up its slack) while sliding the spring into place (photo 2) — this can go smoothly or take several tries. I then tighten the sync screws (photo 3) the same amount I loosened them during disassembly, typically 4 or 5 turns (you took notes, right?).
TIP: If you have no base point for the sync screws, you can screw them in till the springs are compressed then turn out four full turns — this will give a starting point for syncing.

These Gen-3 choke rods slide through the outer carb mount, then their spring, then the choke actuating bracket and finally the second carb mount (photo 4). If a rod doesn't want to align with the two mounts, either the carbs are not aligned or the rod is bent — they must be slide freely to operate correctly. Note the correct placement of the bracket's tang on the choke plunger (circled, photo 4). Holding the choke rod in place on the outer carb's choke plunger, I tighten the bracket's screw  (photo 5). Give everything a visual inspection and, once again, test the throttle and choke linkages for proper functioning. If anything is binding, it must be addressed before continuing.

(Below) I next install the low speed and main jets. Using a properly-sized screwdriver blade, I snug the low-speed jets in place. Next is the main jet holder; I tighten the holder with a 7mm socket using only firm finger pressure on a 1/4" ratchet or wrench. Then the main jet is screwed firmly into place.

(Below) The float assemblies are next; the float holders (with washers) are firmly screwed tight with a 10mm socket, again using firm finger pressure. Drop the float valve into place and set the float in position, fitting the float's tang under the valve's wire. Slide the pivot pin into place, then check that the float bounces up & down freely. If it's binding, figure out why and fix it.

(Below) Float adjustment is a critical step. With the carb set held vertically, tilt back till the float contacts its spring and settles gently — not fully bottomed, just suspended on the spring. I set all Gen-2 and -3 at 9mm as measured from the carb deck. Here, I have my ruler marked with tape at 9mm for an easy visual picture. Adjust by bending the float's brass tang slightly up or down, as required. I use a dental pick or small straight-blade screwdriver. There's a factory tool available specifically for setting the float height, but this simple method works well for me.

(Below) With everything buttoned up in the float chamber, we can install the float bowl covers. I fit my fresh Viton bowl gaskets followed by the drain screws. I install the covers with their anti-tamper nubs (circled, photo 2) opposite of the factory position, as I've removed the anti-tamper caps from the mixture screws, rendering the whole thing moot. This will allow me to make mixture adjustments if needed, and those nubs won't interfere. Your call, of course.
NOTE: Those anti-tamper caps were EPA dictated and do not need to be installed.

I snug the screws with an electric screwdriver, with final tightening by hand. Replacement screws are available on the "Maintenance" page.

(Below) Looking over my workspace, I see only three items left. I test fit the fuel line "T" fitting and trim the lengths as desired to get a useable angle to later join with the fuel line from the pump. Slide the clamps into place, and I always add an extra at the bend point shown, but it's likely not necessary. Next is the idle speed adjuster cable. I screw it into place (note the placement of the spring and washer) and upon contacting the throttle wheel, I screw it two full turns — this gives a ballpark idle speed. Finally, the vent hose can be installed at your option. Its function is essentially to keep water out, so it could be trimmed shorter, reconnected to the emissions hardware downstream, or left off, your choice. I just trim mine below the first curve and angle it downward.

Before these carbs are mated to an engine they're leak tested. Now is the time to find and fix a leak, not after installation. With the fuel bottle filled about 2/3 to give sufficient head pressure, I leave them in the plastic tub for at least 12 hours, or even a few days.

With this final test passed, they can be drained or transferred directly onto the engine for tuning.

TIP: I actually use water for this test, which allows me to safely do this indoors. Also, if a leak is present, there's no gas to deal with while finding and fixing the leak. Just remember to drain the water from the float bowls after leak testing.



​I hope this post helps anyone in need. As always, call, text or email me with questions, comments or constructive critiques.

With my '93 VFR750 stripped and on the lift (previous post) for the purpose of some carb tuning, the next couple of months would be the perfect time to help out anyone who's thinking of having me rebuild their Gen-3 VFR carburetors, or just a simple jet clean, check & sync on a running engine.

If that might be you, contact me:
​[email protected]

In this tutorial I detail the minimum steps needed to access the carburetors when we're in the position of requiring only carburetor access. This is also the starting point when a more thorough breakdown is desired for additional service — I have a video of that process on the V4 Dreams YouTube channel. There's also a video available detailing the carb removal itself. The procedures below apply, at least in principle, to the other carburetor generations of VF/VFR. ​For further reference, the Factory Service Manual is also helpful.
The process will require removal of:
• Seat
• Side Fairings
• Tail Cowl
• Fuel Tank
​• Carburetors

(Below) After seat removal, I begin with the side fairings. Loosen or remove the four Dzus fasteners on the side fairing plus the three fasteners on the bib fairing (the bib will remain in place). The upper bib fastener is not a Dzus, bit should be some sort of annoying plastic pin. I also remove the rear screw fastener on the headlight fairing (pink arrow) to allow some movement to aid in angling the side fairing free — be very gentle separating the side/headlight fairing seam, it is stubborn and prone to cracking. Both sides need to be removed so repeat on the opposite side.

(Below) Next, I'll need the seat cowl out of the way in order to gain access to the fuel pump/filter area on the left side. Remove the four side screws and the two bolts under the seat. The cowl can be propped upward or removed completely by disconnecting the tail and turn signal wiring connectors. (Gen-2; only the fuel pump cover fairing need be removed, the seat cowl remains in place). With the fuel pump accessible, I disconnect the pump's power supply connector; this is done in order to later tune the rebuilt carb set without the fuel tank installed and I don't want the pump running dry. I then use the underseat space as a handy tool shelf. 
(click on images to enlarge)

(Below) Let's get the fuel tank off. First, remove the tank's rear hold-down nut & bolt which will allow the tank to be raised a bit to help with the following details. With the petcock "off" I disconnect the fuel line at the filter under the seat cowl — have a rag or small container ready to catch the residual fuel in the line and filter, then plug those openings. Also on the left side, I'll need to remove the frame bolt securing the fuel line — the line and bracket will stay with the tank. Lastly, unplug the fuel gauge electrical connector on the right side. The tank removes by sliding rearward, which frees the front mounts, and lifting clear.

We now have access for carburetor removal.

(Below) Carb removal has been covered here before, but here's the procedure for the Gen-3.
Remove the airbox cover screws and cover, then the base screws, remembering the hidden screw in the front. The base screws are held captive and are of a different design, see photo. In this case the two emissions hoses have been removed from this cover and plugged (circled), if not, then slide those hoses off the cover. Finally, while lifting the base, slide the oil separator hose free from the engine — no need to move the spring clip, the hose will slide off and on with the clip in place.

(Below) Specific to the Gen-3, I'll need to pivot this thermostat housing brace (pink arrow) rearward to provide access to the #3 mounting band screw. The brace is bolted to the engine (green arrow) and to the housing (yellow arrow). First I'm removing the housing screw; here, it's a 5mm allen screw, but yours might be a phillips or hexhead screw. Next, loosen, but don't remove, the 14mm bolt at the rear just enough to provide free play to move the bracket outward and pivot it to the rear, where it can remain.

(Below) Next, I can loosen the carb insulators (boots) using a long-shaft JIS screwdriver or 8mm socket. The right side carbs are accessed from the right side, the left from the left side. Loosen only the upper band screws, leave the lowers alone. You don't want to completely remove the bands' screws, so I've learned to make 25 quarter-turns on the tool. I then pry both rear carbs upward to free them, gently levering on the carb bodies, not the choke rod! Once the rears pop free, simply lift upward on the carb set (the fronts will pop free) and carefully lift away from the bike. Finally, drain the carb bowls on the bench and stuff some clean paper towel into the intakes.

Today is the unofficial mid-point of the winter season here in the north hinterlands, so I take a moment to reflect on warm days and clear roads, confident in their eventual return. In anticipation of those days, I'm putting together my own video kit to record some of my favorite local roads. I have no aspirations to become yet another YouTube motorcycle vlogger, but rather to preserve a small collection of memories for the future. If I can put together something presentable, perhaps I'll add a few to my YouTube channel during the coming riding season.

In the meantime, here's a video from V4 Rider showcasing a pleasant ride and the great sound of the 800 VTEC — turn up the volume and listen for the distinct VTEC transition as he accelerates out of the turns.

UPDATE: Reserve Not Met at $3150 with 10 bids

What: 1986 VFR700F Interceptor
Why: 1-owner, low miles, original
Where: Simi Valley, California
Price: Auction with reserve

Here's a rider-grade 700 which will check many buyers' boxes. One-owner, all original, red/white/blue, low-ish 11,752 miles and presentable overall condition. From the seller: "Shifts smooth, all original, no modification. I bought this bike off the showroom floor, never been out in the rain, always in the garage."

Not many more details in the listing or closeup photos. The seller notes a small dent in the fuel tank, but a closer look at the provided photos show several scuffs and chips from 40 years of ownership. However, the original mufflers seem rash free and the bike presents as complete and original. A deep cleaning and detailing would have worked wonders here, but this one should clean up nicely. It will be interesting to see where the bidders place this bike's value.

Reader Michael S. recently sent along this image of a custom license plate frame he had made for his truck. They're also available for motorcycle-sized plates. Click on the image for his online source.

Yesterday evening an eBay auction ended for this beautiful VFR750R RC30 with no sale. Sale or no sale, the auction still provides a snapshot of the current market for the RC30, an iconic collector bike if there ever was.

This particular example is a U.S.-spec 1990 model and is claimed to be completely original except for tires. It has a documented 2801 miles, spending the past 37 years as a static collector bike, not run, with no fuel in the tank. The seller, Ron Susser, a vintage vehicle dealer/broker, offered some 200 detailed photos in the listing, which show what a pristine RC30 this is.

"The condition of every one of the finishes, from the paint to the trim to the finishes on the engine, is nearly flawless…every part on this RC30 is original and as it left the dealership floor."

The original factory rear paddock stand, tool kit, owners manual, two keys plus additional factory paperwork and other items are included in the sale. He also offered to recommission the bike to roadworthy status if the buyer wished.

The bidding stopped at $59,600 after 83 bids. I think that number further supports the current cooling trend in the collector market, as that kind of money would have gotten you a more average condition RC30 just a few years ago. The RC30 is a bellwether indicator of that market, the canary in the coal mine, perhaps?

What: 2007 VFR800 Anniversary Edition
Why: Well-kept, nice additions
Where: San Francisco, CA
Price: $7000

Apparently the '07 VFR Anniversary Editions haven't gotten the memo about the "cooling" of the classic vehicle markets. Case in point; this past October a pristine, very original example sold on BaT for $9600.

This listing is a little different animal, sporting several nice farkles and more miles (12,000). The seller describes the bike as "perfect condition, flawless bike." Mods include a LeoVince exhaust, aftermarket windscreen, Power Commander and white wheels, the rear a lovely Gen-3 8-spoke. The rear seat cowl and centerstand are present and the photos show off the beautifully-kept one-year paint scheme. No word on whether the original parts are included with the sale. This is a non-ABS example.

Good to see the Anniversary Editions finally coming into their own in the classic bike market.