[ducatiman]

Problematic "check valve" (actually a main jet) diagnosed. Both the clogged jet orifice and the stuck rubber check valve diaphragm removed, disassembled and serviced. Replacement, not repair, is the accepted industry standard procedure. Very tiny, near microscopic work involved. For size reference, a 10mm socket shown in pic. The little brass check valve is pressed (rather than screwed) into the body. The tiny black circle is the diaphragm which is captured in the nozzle end of the valve, held by 4 tiny spring arms. 3 Fuel openings are visible. This'll be a runner tomorrow.

 

[ducatiman]

1978 CB400T Honda twin carbs needing serious attention. Note presence of red RTV, ugh. All tuning components removed, in process of restoration.

 

[ducatiman]

afternoon into evening, a good days work produces.......

RUNNERS!

 

[ducatiman]

interesting these oldie Honda Keihins using SAME brace hardware, float valves, rail orings as your EX500!

 

[ducatiman]

A cracked spill pipe found in 1 of those Honda/Keihin CB400 bowls pictured, visible only after full cleaning and close inspection. Thankfully, I'm ready to go....prepped with proper replacement method and piping in stock. With owners blessings we're moving forward. Evidently, THIS is the year of the spill pipes.

The cracks were well below normal fuel level......would have been instant leakers, repair imperative. Having the other factory bowl in hand enabled me to copy pipe length/opening to exact spec. Not bad, eh?

 

[ducatiman]

The '78 Honda cB400 carbs as received......note stuck slide in RH carb? Explains the stretched return spring in order to "fix" it. On these, the slides rise into the carb tops. On the stuck side....an internal imperfection preventing rise/fall. I used fine valve lapping compound to regain unimpeded slide action. The cause of it all? A barely perceivable telltale mark on the cap....somebody hit the cap, throwing it out of round. Anyways....every oring renewed, OEM jets restored, every circuit clear, synched...wet tested perfect, owner to swap out the stretched spring....otherwise bolt-on ready to go. 42 years old!

 

[ducatiman]

stumbled upon a pic from 2013, the first set of carbs I ever did for a EX forum member, this fella in California. Felt bad for the guy experiencing ongoing carb issues so I offered and did a bit of a favor. 7 years on already...wow.



And his unedited reaction after delayed response on receiving ......... "Sorry was out riding, holy crap like a new bike, fired right up 3rd try, was rough for a minute after warmed, slid choke off did die but quickly figured out was idle, set perfect now and the bike runs like never before, super snappy, so quiet smooth, and compression is awesome at pipes both thumpin good could not be any happier, went for a quick 20 minute ride to be safe, and was awesome, idle kicks back down throttle feels great, thanks again ducatiman."

 

[ducatiman]

Today started a Ducati/Mikuni resto. These 25 year old. Ugh.

 

[ducatiman]

Duc main jets as removed

 

[ducatiman]

major progress, near done. compare to pics above.

 

[ducatiman]

good info, Keihin/Kawasaki and Ducati/Mikuni rail filters are fully interchangeable. Clearly shown here installed in Duc fuel inlet. Completed, wet tested, synched, packed and goin' back home tomorrow.

 

[ducatiman]

Next refurb up on the bench, mid 80's GL1200 Honda Gold Wing, set of 4 attached to air filter base. Complicated, long linkages. Options...I've got some various attack methods at my disposal. We shall see. Looks like fun, eh?

 

[Davenay67]

Next refurb up on the bench, mid 80's GL1200 Honda Gold Wing, set of 4 attached to air filter base. Complicated, long linkages. Options...I've got some various attack methods at my disposal. We shall see. Looks like fun, eh?

View attachment 53045

View attachment 53046

One of the reasons that you see old GL1200 and GL1500 Wings for sale cheap is because the carbs are gunked-up and need a good cleaning. It's a big job to even get to them, let alone the more complicated cleaning job required.

Can't wait to see how these turn out....

 

[ducatiman]

Disassembly phase near complete, though I further plan to remove 1 carb at a time using fixed linkage points (as opposed to adjustable linkage points) Motive to retain choke and synch linkage adjustments best I can to enable easy final tweaks. These carbs are set on dowels, the sealing orings NA from Honda. I'm on my own on sourcing.

Pilot screws plugged, not capped as on EX. Requiring use of drill and easy out. I'm sure Honda never intended removal on these, but we do! . Keihin pilot screw orings same as the EX! Flat and hardened, too!

Individual component cleaning phase will commence Monday. These tricky......dismiss that "carbs are easy" total BS you read on the internet. Not going in both barrels ablazin' as many parts are NLA on these 36 year old Keihins. Slow, deliberate and sure, extreme care and forethought to avoid any damages whatsoever.

 

[K-woppa]

Disassembly phase near complete, though I further plan to remove 1 carb at a time using fixed linkage points (as opposed to adjustable linkage points) Motive to retain choke and synch linkage adjustments best I can to enable easy final tweaks. These carbs are set on dowels, the sealing orings NA from Honda. I'm on my own on sourcing.

Pilot screws plugged, not capped as on EX. Requiring use of drill and easy out. I'm sure Honda never intended removal on these, but we do! . Keihin pilot screw orings same as the EX! Flat and hardened, too!

Individual component cleaning phase will commence Monday. These tricky......dismiss that "carbs are easy" total BS you read on the internet. Not going in both barrels ablazin' as many parts are NLA on these 36 year old Keihins. Slow, deliberate and sure, extreme care and forethought to avoid any damages whatsoever.

View attachment 53048

View attachment 53049

What's up with that dashpot under the plenum? It looks like the fuel supply.

 

[ducatiman]

Book proclaims "air control" and "purge" valves on the bottom side of airbox (which is what you are lookin' at). AKA Pair (or in this case a fuel vapor Evap system) and decel valve (preventing popping). Vapors routed into the intake system via vacuum, cutting down emissions.

Fuel supply is via the topmost hose in the pic running horizontally. Note the aluminum fuel rails between the carbs. I need to replace those oring seals at each end, amongst a ton of other stuff.

 

[ducatiman]

note the Purge control valve on the ST1100 I did earlier this year.....some similarities in that Honda again chose to mount under both carbs and airbox, vacuum actuated, of course.

 

[K-woppa]

I see the fuel rails now. I was looking at the picture that only shows the decel valve. I've not seen them plumbed in that way before. That whole assembly will be a thing of beauty when you're done with it. Soichiro will be smiling down on you.

 

[ducatiman]

I'm hopeful for overall success but hope Mr. Honda is not pissed that I removed the plugs intended to deny access to the pilot screws (1 of which was set at "0" turns, btw)
But I'd guess in view of oring renewal, metering tip and circuit cleaning, he'd offer a reprieve. The utmost respect, his corporate products incredible, the big Wing included.

 

[ducatiman]

allowed this Keihin single carb from Kawasaki Bayou 4X4 to jump the line today. All circuits clear, new consumables (exact same as EX500) and all the usual cleaning methods resulted in major transformation.