Honda DOHC-4 - Randakk Master Carb Overhaul Kit®
Randakk Master Carb Overhaul Kit® for Honda DOHC - 4 Models
WORLD'S BEST DOHC - 4 KIT!
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DOHC - 4 Master Carb Overhaul Kit
DOHC - 4 Master Carb Overhaul Kit
DOHC - 4 Master Carb Overhaul Kit
DOHC - 4 Master Carb Overhaul Kit
Beautifully Restored CB1100F Carbs by Tom Bøhn of Hov, Norway using Randakk's Master Carb Kit
"Randall, I've received and installed the DOHC-4 Master Carb Kit. It actually arrived Monday!! Given the holiday, I was very surprised. Everything went together without a hitch. I have a couple other items to address before firing the bike up, but wanted to let you know the kit was perfect. The bike (1980 CB750C) had been sitting in a barn for 10 years and a field for 10 years before tha, so all the o-rings and such were hard and nasty. Your kit was just the ticket."
"Well, I'm fully back on the road now and I'm still impressed with the kit. I've got about 250 miles on it since installing your DOHC-4 Master Carb Kit. No crazy leaks or anything and the carbs work as good as they did from the factory I'm sure."
Stan Blosser - Coopersville, MI
The architecture of these carbs is very similar to the GL1100, CBX and CX-500 carbs that I have been supporting with my proprietary Master Kits for quite some time. After fielding numerous requests, Randakk's has decided to extend coverage to these models.
This kit is proprietary to Randakk's...you won't find this available anywhere else at any price. Sourced are the best available parts from 3 continents and combined them in a unique combination that represents real value. This kit is appropriate for listed 1979 - 1983 DOHC Fours with original carbs.
And unlike other kits on the market, my kit even includes those pesky carburetor body side-to-side sealing o-rings that seem to give so much trouble on units that have been parked for awhile (details below).
Note: The round o-rings in each Master Kits are made of Viton rather than ordinary nitrile (Buna-N) as found in other aftermarket carb kits. Viton is superior to nitrile in terms of:
- Heat tolerance (400 degrees F vs. 250 degrees F)
- Compression set
Did you know that one good case of severe engine overheating can ruin the carb o-rings found in ordinary kits? My o-rings are the best available! Get Viton Proof on our Blog!
Randakk's o-ring sizes are precise. They're equivalent to the exact sizes specified by Honda for each fitment. Not "close-enough" sizes as in many of the other aftermarket kits Randakk's has evaluated.
Randakk's DOHC - 4 Master Carb Overhaul Kit
B" Version shown (others similar)
Unlike ordinary aftermarket kits, each Randakk kit provides everything listed for all 4 carbs plus other items required for splitting and rejoining the carbs to replace the cross carb fuel transfer tubes. Included are rebuild kits for the air cut-off valves and accelerator valve.
Only the highest quality items are included. This kit has been thoroughly tested. This collection represents the best value available in the market. Trust us, you'll need everything in this kit to do a proper overhaul of your carbs.
Here's what you get:
- 4 - fuel (idle) mixture screw (2.8 x 1.1 mm)
- 4 - float bowl drain screw (4.3 x 1.3 mm)
- 4 - CV Slide Top Limit Plug (6.9 x 1.3 mm)
- 1 - accelerator pump passage at float bowl (5.0 x 1.3 mm).
- 6 - Main Fuel Transfer Tubes (5.8 x 2.0 mm)
- 6 - Accelerator Fuel Transfer Tubes (3.8 x 2.0 mm)
Float Bowl Gaskets - 4 of each:
- Constructed of superior Viton material to resist the components of modern gasoline.
- 4 Air Cutoff Valve Overhaul Kits
- 1 Accelerator Pump Overhaul Kit
- 4 idle mixture screw washers
- 12 float bowl screws (4 x 16 mm)
- 1 mm cotter pin for accelerator pump linkage - 1 supplied (simple item, but hard to find elsewhere)
- 8 Viton rubber blanking plugs - cover access to idle fuel jet (2 sizes supplied to cover all variants)
- 8 high quality, plated M3 x 6mm (0.5 pitch) panhead screws for securing choke butterflies
Also, there are no float valve/seat assemblies in our kit. Many aftermarket rebuild kits include float valve/seat assemblies of dubious quality. In the past, there have been many problems with these aftermarket items. Most of the problems related to the aftermarket float needles being incorrectly sized (too short) resulting in unreliable (or nonexistent) fuel shutoff. Some are OK. We've not included them in this kit, because the rubber tips and seats on the OEM item will last nearly forever and can usually be cleaned and reused.So, we've left float valve/seat assemblies out of our kit to keep the cost down and give you a choice on what to buy if you think new ones are needed. Our strong recommendation: use OEM Honda float valve assemblies!
You will need access to good reference material for a successful rebuild.
Consider Mike Nixon's booklet, Cleaning the Honda DOHC Four Carburetor. The 37 page booklet is an excellent resource. Much better explanation and photos than the official Honda Workshop Manual. 140 quality photos and illustrations.
Artwork Courtesy of Mike Nixon
This booklet and other Instructional Guides by Mike Nixon are available directly here at Mike's Book Nook.
Randakk's recommends that you also refer to the official Honda Factory Workshop Manual. There is some critical information there on rejoining and aligning the carb bodies to prevent binding of the throttle and choke shafts...very important!
My Master Kit includes all the o-rings needed for renewing the fuel transfer tubes (main and accelerator).
Also included are 8 high quality, plated M3 x 6mm (0.5 pitch) panhead screws for securing the choke butterfiles. The choke butterflies must be removed during disassembly of CBX carbs to renew the side-to-side transfer o-rings. The staked OEM choke butterfly screws are very difficult to re-use. You will need to use some medium strength Lock-Tite to secure my screws.
1. No jets or jet needles are supplied with our kits. These can normally be cleaned and reused. Aftermarket needles are not sized as accurately as the OEM needles and may introduce lean / rich problems where none existed. Unless your needles are worn or bent, reuse them. If you try to buy jet needles from Honda, you'll discover that they are only available as a set which includes the CV slide, cap and jet needle. The price will make you faint! If you need jets, buy aftermarket kits such as those from K&L or spring for the genuine Honda bits.
2. No float valve/seat assemblies in our kit. Many aftermarket rebuild kits include float valve/seat assemblies of dubious quality. There've been many problems with these aftermarket items. Most relate to the aftermarket float needles being incorrectly sized (too short) resulting in unreliable (or nonexistent) fuel shutoff. Some are OK. The rubber tips and seats on the OEM item will last nearly forever and can usually be cleaned and reused. If you decide to reuse your existing float assemblies, be sure to remove and clean the small fuel strainer beneath the float seat! Randakk's has left float valve/seat assemblies out of the kit to keep the cost down and give you a choice on what to buy if you think new ones are needed. If you need new float valve/seat assemblies, you can buy the OEM item and not have a worry. This way you'll also get new fuel inlet screens (the plastic strainers installed below each float valve). You will need to order four. Or, take a slight gamble and go with aftermarket float valve/seat assemblies which are available at reasonable cost from numerous suppliers.
3. All kits include 8 rubber blanking plugs which cover the access to the idle fuel jets on most models. Supplied are 2 sizes to cover all variants. Honda issued a few "oddball" versions of these carbs which require a slightly larger OD blanking plug. Official documentation on which versions require which blanking plug is limited and contradictory.
per Mike Nixon:
"I have noticed on a few DOHC carbs, for example early 900C and the non-U.S. model 1100R, the standard size rubber plug on these 3-jet carbs does not fit correctly and the larger CX series plug must be used."
4. Confusion regarding the so-called "2-jet" DOHC-4 carbs: "2-jet" carbs were found on a minority of DOHC-4 models...notably the CB1100Fs. These have only one main jet and a removable idle jet not covered by idle passage plug. Passage plugs are included in all Randakk kits, but removable idle jets (without a cross-drilled port to the main jet tower) should never be covered by an idle passage plug, because they feed directly from the float bowl. Generally, there is no cross-drilled passage from the main tower to feed them as in 3-jet carbs. However, there are a very few anomalous DOHC carbs with removable idle jets, that do have a cross drilled port to the main jet tower. These DO need an idle passage plug…usually the larger OD version that are supplied.
5. The contents of each DOHC Four Master Kit is identical except for variations on the Accelerator Pump and Air Cutoff Valves
The DOHC Four Master Kit includes 66 total pieces (Count each air cutoff overhaul kit and accelerator pump kit as only one piece each in the total count even though each actually has a diaphragm, spring, seal, boot, etc.).
Considerable skill is required to install this high quality kit correctly. Since Randakk's cannot control this important variable, there is no warranty on these. Rest assured that they are of the highest quality materials and workmanship. Each kit has been carefully packed and inspected to ensure that all items are included.
Warning: Please open the package very carefully when it arrives. Many of the parts are very small so take appropriate precautions. If you chose to open the package in the dark over your gravel driveway, after 1 or 12 beers, please don't later complain that you are a "few o-rings short." Seriously, do be careful when you open the package!
Not sure can handle your own rebuild? The check out Randakk's Approved Carb Rebuilder Program.