Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Lobo on February 13, 2013, 08:35:34 AM
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Gents,
About to tear down the carbs & overhaul. Before I start I note a couple of small plastic 'tie rods' tying the 1/2 & 3/4 lifters together. They're both cracked / broken.
What is their job? - the bike seemed to run fine, and any tips for re fabricating them - will light aluminium sheet do or will that be too stiff?
Ta muchly,....
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They should be thin stainless, will check thickness later. Mr cooper should be able to help you source a pair.
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Thanks SweetPeaUk,
But... what is their purpose? And secondly, I'd have to say the (broken) pair I have look original - are they aftermarket perhaps?
And finally, if thin stainless, or plastic as mine were, do they need to be flexible?
Cheers,
Lobo
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I think they are for keeping the lifting mechanisms parallel to each other, the theaded end and locknut above adjust the synchronisation so they hold the lifter's so they can't float. They don't help in the lifting of the slides.
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Thickness is 0.32mm, so going to be fiddly to make. I have three sets of carbs and they all use the same material.
Paul
(http://i195.photobucket.com/albums/z225/sweetpeauk/CB400/carbs/tiebar_zps4f7caa79.jpg)
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dont think steve has any left i want,nt 6 off him he only had 2 but you can get new ones from germany ebay
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Thanks guys. Will try ebay... and in the meantime try fabricating a pair from feeler gauges or suchlike - will have to look around 'my office' for suitable scrap.
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I need a coupld of these too. I had one previously home made one which looked like o bit of bucycle tyre ::). I'm happy to search German eBay but what are they called?
Cheers
Lynx
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....yup, I trawled German ebay & had no luck. As for what they may be called in German ...aye carrumba & good luck to ya! I've learned new names for bike parts that I'd have thought illegal if you shouted them on the streets....
Seriously, if you come across a (spare) pair pls let me know...will do the same.
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Will do. In the mean time, it might be a bit of bean can :-X. Must be better than tyre!
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... alrighty, recon I've bought myself 20 or so attempts to get it right...!
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if there not on ebay now keep looking he puts them on every couple of weeks
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here they are
http://www.ebay.de/itm/Vergaser-Verbinder-CB-350-400-500-550-four-HONDA-NEU-/150997533711?pt=Motorrad_Kraftradteile&hash=item232827840f
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Anybody know if these are the same as a 500/4 as i need two for mine.
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they should all be the same
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Just to add a bit about making your own; the feeler guages may offer you quite a resistance to shape them well/drill holes as the material spec calls for a fairly hard spring steel if they are of decent quality.
A more useful scource could be a discarded stainless kitchen sink to give you that thickness of material.
If you were to drill two holes the correct distance apart in the steel, then sandwich in between two pieces of plywood clamped with bolts and nuts through the holes, then it would allow you to shape them by hand without bending them. Also you can make more than one at a time in the same clamp to halve your work.
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Thanks K2-K6,
Already gone down the clamping route; using aluminium sheet & abbuting peripheral rivets to hold the 'feelers' rock steady within. (the back of the pop-rivets then sit into corresponding holes of a large wooden block to resist twisting in the drill press)
The feelers I've used are .35mm & .40mm, ie two of each sandwiched, to give 4 pieces.
After I get (the bloody difficult holes drilled) I will rivet through those (now including large washers to give external radius) and keeping the sandwich in tact then grind the shape.
Well, that's the theory...
.....and in the meantime will keep an eye on ebay etc - thanks to Steve400//4
Cheers!
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Any Tec guru out there care to explain wht the 400F carbs so 'complicated' versus the older CB750's? Specifically the lifter mechanism, which on the 400 appears overly complicated with sliders, springs, elbow sockets, fancy dust seals...versus a good old up/down external vertical lifter?
Ta.
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lobo,
Dead right complicated and fiddly all those years ago I hated them.Luckily the only 400/4 I restored the carbs apart from usual cream krackered o rings and cleaning I did not need to take them to bits.No help to you but I would take lots of pics when you attempt to do them.
Cheers
Bitsa
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It does say 350, 400, 500 ,550 in the title.
I tried doing a bit of research on it but all I found was Honda part Nos. for the assemblies including this part is 16029-323-004 and 16030-323-004 fits CB400 and CB550.
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323 middle number is oruginaly 500 four
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Lobo, your question about the complexity of the 400/4 carb linkage versus the CB750; the carb slide travelling vertically is lifted by the rotating arms so giving two seperate paths of travel...the sliding action of the lifter forks is fairly crude in it's junction with the slides and maybe a bit high on friction but very simple and, it seems, without many real problems even after all these years.
The 400 one however, when you remove that single sliding link, then needs an elbow to connect the two different paths of travel. To maintain a stability and parity between each linkage then simply requires a far more detailed set of components (as you've found) and although it may offer a solution in pure technical terms it may have lost sight of any advantage it could hold.
Honda certainly do this fairly often.....a good example is the enclosed disc brakes used of a CBX550...have a look to see how complicated they made those !!
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The German guy selling the spring steel replacements on eBay will do a Buy It Now price and will take payment by PayPal. Mine arrived in super quick time.
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Thanks gents... Lynx ta, but a day after starting my own ss connectors found a couple of 2nd hand ones on ebay which will do the trick.
K2, yup still confused as to 'why?!'. This linkage mechanism would have had to get past many folk in Honda including the accountants, each who will have been aware of the extra complexity & cost...aware too a simpler in-house solution that was working fine on their '750.
As for friction...I'm not convinced, there are so many extra components in this deign that the summation of system friction is surely greater. Certainly to my non-calibrated oaf hands there is no appreciable difference.
The only thought I have is perhaps an effort to minimise/delete all slop/play arriving at the slider. The 750 K1 (onwards) fork lifter both pulled & pushed - though any play here could have been easily 'sorted' with a 'big' spring against the slider (a-la earlier K0?). The 400's system with spring clamped elbows / connectors etc presumably keeps all slop out, and therefore the carbs balanced at all times.
BUT, whilst I'm curious I'm no engineer... always keen to learn, and just guessing..
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Ah, but the carbs were not a Honda part but bought in as an assembly at an agreed price
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I thought that after I'd replied Bryan, they usually use Kiehin or have done historically.....but the design spec would usually go out to the supplier and then test and approval would happen during development prior to ramping up for production once it met expectations.
Lobo, you're right in the sense that looking back on it now, then it seems to offer complication along with no really significant and obvious advance over the 750 spec......saying that though, it's easier to look back and see that now........also during original design the thought that they would last this long and someone would want to renovate them just didn't seem to exist in the manufacturing proccess then.....doubt it does now either.
Also we were seeing some of the last pure slide operated carbs generally at that time as development was heading toward CV type carbs for road bikes in which the throttle just opens a butterfly flap with the slide just opened via a vaccum circuit....these sohc motors being design decendants of the sixties Honda road racers, with Honda's managment keen to show any level of sophistication as a marketing plan/advantage.
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now parts are available from gerbens1956 http://www.ebay.co.uk/itm/Honda-CB500-CB550-CB350-CB400-Four-set-reproduced-carb-stabilizer-springs-/121073360635?pt=UK_Motorcycle_Parts&hash=item1c3088defb and he speaks english!!
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Ok, into the actual rebuild now...
I note that the choke butterflies are sprung closed.... meaning that should the grub screw (whatever) in the main choke lever linkage 'let go' all four carbs will go full choke & the engine stop. Seems somewhat unsafe if your doing 80 mph in the outside lane at the time; should I be worried / mod this - or have those wretched elf'n'safety types finally got to me? (Odd little things on these old Hondas do surprise me - eg my K2's single 15A fuse supplying... everything. Low beam to high beam in a turn one night... blow the fuse...coils shut down...work cut out!)
Also, staying on this choke lever linkage (and noting no components bent / modded (yet!)) it appears I can't quite set it up to give BOTH full choke and 'WOT' settings due insufficient choke lever rotation. If I set the butterflies to full close, then at 'ball bearing engagement' / choke OFF setting the butterflies are not parallel to airflow, but about 10 degs inclined. Looking straight on they're just about within the confines of the shaft profile. Again... a slight mod needed?... filing a tad off the backside lever pivot brass limiter nipple?...... or normal / don't fret?
Finally - the small screws that attach the choke butterflies to their shafts. Best way to ensure they don't vibrate free....Loctite... or what? Appreciate they're in the fresh air side of the carb, but nonetheless concerned stray petrol vapour may ultimately break that bond?. Could, I guess disassemble the sliders / needles out & 'rivet' the threads whilst back-supporting the screw heads....but not really wanting to take a hammer anywhere near my carbs!
Thanks in anticipation...
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Anybody know if these are the same as a 500/4 as i need two for mine.
£12.50 for two from Holland on ebay
http://www.ebay.co.uk/itm/Honda-CB500-CB550-CB350-CB400-Four-set-reproduced-carb-stabilizer-springs-/121073360635?pt=UK_Motorcycle_Parts&hash=item1c3088defb
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I thought someone else would pick up the choke position question......but I'll add my bit for what it's worth.
I'd set the butterflies to be a best position at full open, then accept any compromise at the closed/choked position. They just don't seem to need absolutely closed chokes to start in most of our climate conditions and you very quickly back it off anyway almost as soon as it's fired so shouldn't really make any real compromise. Not sure if this would be a text book method, but seems logical on a fairly small carb to help maximum flow and to make sure it's running when warmed up without having any undesirable choke/mixture effect during normal running.
As regards the failure of the operation which would force a closed choke situation, I've not heard of any doing this but Bryan may be able to bring more to this from his experiences.
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Thanks K2-K6
That sounds sensible - don't particularly want to be filing down nipples etc & making it all look a bit bodged.
Q...if the butterfly is at say 10 degs off horizontal (open) but contained within the profile of its shaft (looking down the carb throat) will WOT performance suffer? ie MUST the choke (OFF) be absolutely parallel to airflow? If you reckon not then I can indeed get full choke ON.
Q. Care to comment on (red) Loctite holding the fastening screws on the choke valves versus the originally 'punched' protruding ends forcing them oversize? Should I worry?
And yup, I'm thinking health & safety morons getting to me... if just one person had demised as a result I suspect would have been sorted long ago....
Thanks again.
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Now there's a big question, about butterfly angle I mean. The fact that it is there is producing the most obstruction I guess, as opposed to a racing carb with no choke facility to restrict it at all.
I'd guess that there would be next to no measurable difference if as you describe they are contained within the diameter of the spindle, but you'd never be able to tell without accurate measurement anyway....apart from a verified top speed run or dyno session....In short I'd not worry about it at that deviation.
Red locktite 271 fits the application as far as I can see.......i.e. a virtually permanent locking function that takes a considerable level of heat (spec says 250degC) to in any way effect a dissasembly of the parts once it's set......assume that the parts are fully degreased prior to application.
I know there are others that will only accept a mechanical locking method if used orignally, so you have to really make a choice for yourself.
The doubters will probably all be flying in plastic aeroplanes soon (Boeing dreamliner et al) that'll scare them.
Maybe somebody else can offer their experience on the locktite question to help you........
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Must admit to never having removed the choke plate screws, for the simple reason that i didn't fancy having to refix them!! As to airflow these carbs are, in my opinion, such an old and agricultural design that a disturbance of airflow was not even considered when thewy were built.
i have in fact been on the motorway with a 500 when the leggings knocked the choke lever on and yes it does slow down quick but not as bad as an engine seize!!
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Thanks K2/6, Bryan,
Job done, will be months before I can verify all upto scratch as engine about to go for recon and thence (with summer leave) will rebuild the bike.
Still totally 'befuddled' as to why the darned set-up has to be so complicated - from my untrained eye it all appears to offer nothing over the simpler 750/K2 onwards carbs.
Below the finished product - painted & lacquered in petrol resistant finish. Would have dearly liked them vapour-blasted & plated etc.... but living here in a third world country and re-conditioning bits you've dragged back in yer suitcase has limitations! Vapour-blasting etc may arrive here in oh...50 yrs. If the finish doesn't wear well it only has to last a couple of years to my perm return & then will do it all over again....ugh.
Cheers & thanks to all for the various inputs - the balancer SS tie pieces await me in Hampshire..I hope.
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Just make sure you put them on the right way up :).
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Thanks OddJob, will sleep a little better on the choke flap screws comment. If you're a glutton for punishment, sure, spend hours cleaning, spraying, lacquering....or simply bung the bits in a box & take 'em somewhere to be zinc plated whatever, at a reasonable cost! (I'm assuming you live somewhere that can offer such a service). Bonus is they'll come back original looking.
Or, how's about.....http://www.gaterosplating.co.uk/Zinc-Plating-kit.php.
Gawd I wish I were back...(this stuff not allowed an aeroplane)
Yup, as in my last sentence, (and not knowing their correct name) those 'links' await me in Hampshire and will be fitted once I get home this summer.
Cheers...
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Does anyone know where to get, or what to use for those felt 'washers' in the carbs where the linkage shafts go in? Mine are even broken or lost :-\.
Cheers
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If you join the yahoo group "cb400F" there is a PDF in the files section that explains how to make your own.
Paul
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Thanks Paul,
I've just had look on Yahoo. I did a search in groups on CB400F but it just seemed to be Spanish. It that the one?
Cheers
Steve
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I had a go at making mine - but to be honest not a success for various reasons. A bit of a find but I got a job lot of small rubber 'O' rings which appeared to be exactly the size required.... and used those.
If you do go this route suggest you check first that your o-rings 'petrol proof'
Gotta admit to being unsure of the exact job of felt vs rubber, but did pack a dollop of grease within the flanged washer 'housing'. Suspect my rubber o-rings more air tight - but really of little concern as in the atmospheric / choke side of the carb.
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Try this link,
http://autos.groups.yahoo.com/group/cb400f/
you will need approval to see the group info. There is lots of useful stuff on there so worth checking out.
or you could PM me your Email and I will mail you the PDF
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Hi OddJob...fully understood & appreciated, I should have noted your 'Top end fixer' moniker and realised your experience! I'm personally the least 'arty' person I know and any deviation from the original just looks like a cock-up.
And yup, accept the attached pic looks tacky.... but can anyone advise whether this choke sticker & red paint (on the actual lever) were standard on the UK 400F2s.... I don't remember this from 1978.
(the pic from a DSS 400F2)
Ta...
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Don't remember seeing anything like that on any Honda out of a crate
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Phew...thanks Bryan, have the appropriate sticker included in an American collection of 400F decals, but am pleased it never found its way onto the UK machines. I want my bikes OEM as possible... but there are limits....!