74'' CB550 Four engine

[BooRadley]

I just started to make a 1974 honda cb550four into a cafe racer. I was wondering what can be done to this engine in whole retrospect of things. I haven't been able to find much for it besides racing carbs from keihin which would require serious tuning to put on the bike. I need a lot of help here I am new to the cafe racer culture and any help would be appreciated.

 

[carnivorous chicken]

Get your bike running well first with the stock airbox and exhaust (or whatever set up is on it, assuming it runs well). Worry about tuning it after you have the hang of doing routine maintenance. Unless you're racing or know what you're doing and what you want, no need for engine mods (bore, cam, etc.). Get the hang of that machine first, they're good bikes. And they run well without mods.

 

[BooRadley]

Thank you, i was just curious on whats possible of this engine. I am in the phase of getting it up and running right now, i ran into an issue with carb # 1 being completely corroded so im looking for someone who might have an individual keihan or a set if need be.

 

[warthogcrewchief]

The Keihin carbs are made of aluminum. Aluminum usually corrodes in the form of aluminum oxide (white powdery looking). Have you tried completely disassembling the carb and dipping it? The carburetor dip (found in a gallon can at most auto parts stores) will clean it up like new. All the other parts (with exception to the slide) can be purchased in a rebuild kit. It seems the slides are hard to come by and the diaphragm can be found from aftermarket sources.

If the cleaning doesn't work, what size Keihin carb body are you looking for?

 

[carnivorous chicken]

No rubber diaphragm in these carbs...

 

[Bert Jan]

A few 'cheap' and 'not so cheap' options are;

Install a cb650 cam (use the 650 tacho driver aswell)
stiffer valve springs
remove casting marks from intakes (smooth it out or not is your choice, pros and cons for both)
650 carbs (when using 650 cam)
skim head couple hunderds
electronic ignition
remove starter motor and big battery (weight issue)
use small battery (they need one to run! min amp/h is 3 or so..) use a new regulator/rectumfrier because the stock ones dont work well with little sealed batteries.
dynacoils
high compression/lighter pistons
bore it to 3th or even 4th oversize (scary cause you can't overbore a +1)
pods with right jetting
yoshi exhaust

to the bike;
alloy rims (spinning weight is to be held to a minimum)
chop frame brackets for side covers/airbox/buddy/steerer lock/claxon/pegs
small rearsets
alloy rearend
lower centre of gravity by putting weight as low as possible (battery and such)
simplify wiring to bare
smaller headlights
drill brakediscs
tapered steerer bearings
alu clipons
small alu tank inside resin one, or even better a shiny alu tank

i think you have enough to tinker about now keep us updated!