Topic: Honda CB400f 1977 - set up of carbs

[blackeagles]

i've been rebuilding a cb400f (well the running gear anyway 'cos it was a 'bitsa') and now its time for the carbs which are filthy with dirt and grease so i'm guessing the internals are possibly as bad.
everywhere/everything i have read says that you need a set of vacuum guages to set up/sync the carbs- anyone done it without and how??

[Bodi]

If you avoid removing the slides when doing your cleaning then the sync won't change. If the slides move OK they likely just need some carb cleaner sprayed around them while opening and closing. The needles really don't wear or get very dirty.
If you do need to take the bodies off the rack:
You can "bench sync" them using a small drill bit or piece of wire, adjusting each slide to just drag on it.
Take a look at the gap between bore and slide now, try to get it roughly the same. Note there is no "master" unadjustable slide on this rack. If you don't get the set adjusted back close to where they are the choke advance and, more importantly, the idle stop - can easily run out of adjustment range. Count the threads showing on the idle screw and set that back where it is on reassembly before doing the bench sync back to the existing gap. You should adjust the idle to whatever drill or wire you will use before counting the threads previous to rack disassembly.
If you do use a vacuum sync, leave one slide unadjusted (whichever is hardest to get at, probably 2 or 3 near the main frame tube) and only adjust the other 3 to match vacuum.

[blackeagles]

hi, thanks for that.  i have now taken it all appart as it just wont run other than at about 3000rpm with full choke.

its no surprise to know that none of the needle slides were anywhere near the same as each other, the slow running jets were all blocked, one of the main jets was a completely different 'push fit' jet/different bore, and one of the spring clips was broken in half, the needle was set to pos.2 not 3 (not a major but changed) and the overstop was well off - no surprise it didn't run.

however, needless to say the so called 'arm set/arm set a' lock washers with the tangs that you bend over against the bolt to stop it moving mostly broke off.
this can't be unusual so what have other people used to replace them as you can't buy them.

[Redline it]

maybe a cut bean dip pop off lid would work, or a bottle cap (it might be too thick,) the old pop off beer can is probably perfect in thickness, one thing in tightening that little bolt, it's difficult to hold the spring loaded housing in the center of it position (plus the lock tack washer) it's pretty soft, the bolt is hard, tightening it without holding it i used to do and they always came out ok, now trying to hold it is throwing a curveball  at me. if those are damaged then the slide travel will be off a bit. i'm waiting to find out what this solution to finding a lock washer you find here, and any info on how to snug those ball and socket holders with that little bolt. that's the one thing that always seems odd in the whole carb scene. 

[blackeagles]

the can top is a good idea and i have been cutting open and measuring the tops and bases (sides usually have corrugations) but they are all too thin (between .006thou and .012thou) - the origional washer is .020thou.

However, when my dad died i brought a load of things back from his garage (some of it dating back to the '50s) and luckily there were a few electrical tags from that time that looked useful.  a small amount of filing out the centre to fit th nut and i pared down the sides and cut the tag in half lengthway with one tag turned down and the other up and over the nut and although its not pretty it does the job.

[awrawr]

I just overhauled my carbs. I used stainless steel tab washers from Ebay. All sizes and types available, including with two tabs, perfect for this application.