Honda-SOHC
SOHC.co.uk Forums => Project Board => Topic started by: exvalvesetdabbler on December 24, 2025, 05:48:36 PM
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I have been digging through my boxes of bits and found enough bits to put together a set of carbs.
I'll post what ever I get up to on this thread as I go.
The first job was to refurb the frame and link rod that was stuck fast. Loads of soaking in various fluids and wiggling to get some movement. Made up a jig to drill out the pin so that the link rod could be extracted. Then drill out the hole to 4.4 mm and tap M5.
The jig keeps the drill centered. Drilling out a steel pin from aluminium can result in the drill wandering off centrer.
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Stepped screw to lock in the link rod.
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Remove the felt seals and retainer
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Link rod. This is after 2 days in my electrolytic cleaning bath to de-rust an clean.A bit scabby where the throttle linkage is attached bit at least the bit that engages with the bushes has survived. I'll probably just brush plate this portion.
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Edit. Be careful not to loose the nylon shim washer that goes on each end of the bronze bush.
Regards
Dave
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Time to separate the two halves of the throttle cable rotor. I learned from previous experience that acids and plating solution can get trapped between the two halves resulting in corrosion creeping out the cracks.
I center punched each rivet and drilled out using a center drill. Any residual around the hole can be sliced off with a sharp blade and the remaining rivet on the other side can simply be pressed out.
A center drill with a tip just under 3mm is an ideal size.
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The original retainer rings for the felt seals weren't that great and it was easier to make some new one out of stainless.
[attachimg=1]
I will still try to re plate some of the old ones but I suspect that once they have been cleaned and pickled, there won't be much left of them.
Lots of. De rusting and electrolytic cleaning to do. Sodium carbonate, dash of oven cleaner and washing up liquid. It's a slow process but saves on a lot of scrubbing.
[attachimg=2]
Regards
Dave.
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Nice work and well done for putting in so much effort to overcome the problems.
I can see you recieving order for those stainless felt retainers 👍
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A lot of good ideas there, I like your electrolytic cleaning, will you be replating the parts yourself?
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Jury is still out on plating, depends if I can get a worthwhile batch together to send them out. Also there's a lot of small bits to loose. If I do them myself, I need to refine the brighteners in my tank to get a level finish, and probably try out an alkaline bath for better throwing power to get into all the nooks and crannies.
Regards
Dave
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Most bits cleaned, rust removed. This is the state I would have them before sending off to the platers or plating myself. Flash rusting shouldn't be a concern so long as some residual plate remains. That's the beauty of this clean up method, it removes rust but leaves zinc plate in place.
[attachimg=1]
Regards
Dave
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Nickel plating the ends of the carb link rod. These are quite a soft steel that has been hard chromed and since it's only the end bits that are the worst and in plain sight once on the bike, I decided to clean those up and apply a coat of nickel.
Because of the inverted cone on each end, simply dipping the end in plating solution just trapped bubbles and didn't cover well. I came up with this method using a cable gland to create a cell around the end. The bit above the gland is the nickel anode.
Slow going at 10-15 mA but it seems to be working.
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[attachimg=2]
Regards
Dave
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I had a, little win today, been figuring out how to cut the felt seals while keeping the od and id concentric. Cutting the two holes separately was not reliable.
[attachimg=1]
The solution was to make the two cutters fit inside each other. The outer cutter does the outside diameter and retains the circle of felt. The inner cutter is chamfered internally to cut the inner hole to the size needed.
These are cut by squeezing the cutter against hard plastic in the bench vice so no bruised knuckles which is a bonus.
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This is the felt that I found.
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Just need to do the same for the carbs link rod and the throttle slide arm felts.
Bit of a faff making up tooling but should be able to turn them out like sausages. I was tempted to size the cutters to the same length so that a felt washer comes out in one hit, maybe later
Regards
Dave
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Been making replacement interconnectors to replace the old plastic ones that some folk have been reporting breakages for. I also compared the measurements with the T connector which is brass. On the old plastic ones, the groove width was narrower as was it's inner diameter. Not really sure if the old plastic has shrunk with age or just naff machining tolerances. I made the new ones to match the grooves in the T connector.
A bit of faffing around grinding a groove tool for machining brass to reduce the rake angle to near zero, a sharp contrast to what I have been using for stainless. The tool tip was honed on an oil stone to remove grinding marks that would otherwise show up on the finish of the groove.
Nearly finished after deburring
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Finished item
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Don't think I could make a living doing these, the first one has taken most of the day in between the crisp, biscuits and coffee breaks, on the plus side there were no rejects.
Number two tomorrow.
Regards
Dave
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Nice work. Quite fiddly I imagine.
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Measure 5x cut once!.
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Nice work 👍. If you had a CNC machine and a program I bet you could batch manufacture these. There must be a demand for them because the plastic ones get so brittle they break for fun. I bet DSS and CMSNL would be interested?
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A milling machine would be my first choice if I had somewhere to put it, but yes you're right if someone with CNC capability took it in they could churn them out like sausages.
I had a lot of similar items made at work in titanium and despite the high material cost, the tooling/setup costs always dominated for small batches of around 30.
Regards
Dave
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Some nice work there Dave. It’s a great attitude and solution to parts that are just not readily available. If I had the technical ability as well as the appropriate machinery I would be doing the same.
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I have been distracted the last couple of days trying to get my ultrasonic bath working after 15 years sitting in the loft. It's an old industrial one dating from the 90s that decided to start popping fuses coupled with a leaky heating element which is why it was thrown out at work many years ago. Heater perminateley disconnected and the fault on the transducer board now fixed. It frequency sweeps so I didn't want to give up on it because I would never afford a new one having these specs. After 20 minutes running the water is up to 40 Deg without the heater any way. Lots of bits to degrease now including the carb bodies before they go off for wet blasting. No doubt there will be a few watch straps and jewellery joining the queue.
In between fixing this and other jobs I had a look at the pivot pins that locate the floats, none were particularly great so I set about making some new ones. 2 mm diameter brass rod, 23mm in length and chamfered at both ends.
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The two at the top are old ones.
Regards
Dave
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**********TECH OVERLOAD WARNING! ALERT FOR ODDJOB, ETC. ;D*********
I got my ultrasonic cleaner out of the skip at work and fixed it ...made by Ultrawave.
It worked great for a while then BANG ! popping all fuses. Managed to fix it but after a few months BANG ! again.
When I looked at the bank of output transistors they all had a number hand written on them. I found out that they matched all of the transistors at the factory and I don't have a clue how to do that. I don't think it's just a matter of gain matching... If you don't perfectly match them, then they don't share the current correctly and eventually go BANG! Problem is with the design of these things they are switching high voltages at high frequency into a highly capacitive load.
Ultrawave is similar design to this one.
[attachimg=1]
I do have another smaller one that is of the same era and that seems less fragile. Made by Decon Scientific. Pic is of 300B model but mine is a 400B so larger. Got given it as being 'BER... (Beyond Economic Repair).
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Ash , the one I have is a ex lab Decon model like the beige one in your pics , a 200w version.The QC sticker inside is dated 1990. The problem that I found was with a triac bolted to the earthed chassis. Someone didn't deburr the hole properly and the burr had penetrated the insulator to give an intermittent short. Luckily I had some more insulator pads to fix it after deburring the mounting hole. There's no real chance of getting at the heating element without de bonding the tank from the enclosure. It was electrically leaky sufficiently to fail a PAT test and that's why it was on its way to a skip before I rescued it.
It's amazing the amount of stuff that gets tossed in a skip when a lab closes or no longer needed. My boss would routinely lecture me on hoarding stuff that might come in handy one day, Apparently it costs money to store stuff you no longer need.
Regards
Dave
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Ash , the one I have is a ex lab Decon model like the beige one in your pics , a 200w version.The QC sticker inside is dated 1990. The problem that I found was with a triac bolted to the earthed chassis. Someone didn't deburr the hole properly and the burr had penetrated the insulator to give an intermittent short. Luckily I had some more insulator pads to fix it after deburring the mounting hole. There's no real chance of getting at the heating element without de bonding the tank from the enclosure. It was electrically leaky sufficiently to fail a PAT test and that's why it was on its way to a skip before I rescued it.
It's amazing the amount of stuff that gets tossed in a skip when a lab closes or no longer needed. My boss would routinely lecture me on hoarding stuff that might come in handy one day, Apparently it costs money to store stuff you no longer need.
Regards
Dave
The Decon ones are much easier to fix apart from the bonded on heater pads. I find the Decon one heats up pretty good anyway without the heater on. The Decon ones have a proper toroidal mains transformer but the Utrawave has just mains rectified power and an output transformer, which drives the bobbin shaped ultrasonic transmitters and provides mains isolation . My Decon one has flat bonded on transmitters .
The modern Utrawave cleaners have a PIC micro that drives the power module and if that goes pop you are stuffed as they would never share the code and I bet the PCB costs more than the cleaner is worth. Built in obsolescence eh !
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Still got my blown Ultrasonic Ash. Never got round to fixing it. If I sent you the PCB do you think you could fix it?
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Still got my blown Ultrasonic Ash. Never got round to fixing it. If I sent you the PCB do you think you could fix it?
By all means Ken but quite often they require factory matched parts as in post. Chinese ones can be tricky and of dubious safety concerns.
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May be a while before I can get to it. It's above the door in my garage and my mobility these days leaves something to be desired. As soon as I can get to it and remove the PCB I'll contact you. Thanks mate. I'm kinda low ATM and little gestures like yours mean so much when you feel the worlds against you.
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Always here for you Ken ..you know that mate. Just tell me the make if you know it without venturing outside of course.
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Things are warming up so been able to spend a bit of time in the garage just catching up on a few odd jobs.
First one was to prep a handful of button socket caps ready for refitting the choke flaps. Just drilled the ends M2 so that they can be expanded with a center punch so they can't escape if they come loose. The primary hold down will be loctite, this gives a bit of extra security and they can be unscrewed if they ever need to come out again.
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Second job was to make the brass post that the choke lever rod attaches to. The original was removed some years ago because the hole was quite worn and there was a lot of free play. Secondly trying to replate something that allows chemicals to get trapped us just asking for trouble later on.
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I used M6 X 0.75 thread and made it so the thread bottoms out just before it gets too tight in the lever. On final assembly the threads can be staked together with a blob of loctite for good measure
Regards
Dave
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Very nice work and attention to detail.
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It’s a great skill to be able just to make that missing or knackered parts. I have thought about buying a small lathe but just can’t justify the cost or the space for it. Might have to sell a bike…😳 Nope that ain’t happening.😂
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It’s a great skill to be able just to make that missing or knackered parts. I have thought about buying a small lathe but just can’t justify the cost or the space for it. Might have to sell a bike…😳 Nope that ain’t happening.😂
You've always got Ian. 👍
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Indeed Gareth! He’s already helped me out a few times. He’s a bit of a legend here. We won’t tell him though! 🤣
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A lathe is the best tool you never knew you needed until you get one Johnny.
Seriously go for it if you can and you have the space. You can get a good Myford ML7 with a single phase motor for not a lot of money these days. The one I would go for would be a Super 7 with a gearbox but they are expensive. I have a ML7, I paid £500 for it about 8 years ago and it came with a stand and a suds tray.
Once you get a lathe you will wonder why you never got one before!
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This is exactly the same as mine 1970s Emcomat 7 with milling head. It was made in Austria ....I think more modern ones were made in China ...I don't use it that often ( did woodwork at school :-[ ) ... but really handy for making small parts for my bikes. I paid about £500 for it about 20 years ago.
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This is exactly the same as mine 1970s Emcomat 7 with milling head. It was made in Austria...
Indeed 8)
We had an Emco 8 in the company I spent my apprenticeship (electromechanics and mechanical engineering) at, very versatile machine... (back in the day we still repaired things instead of replacing...)
Got me a small Erba Compact 300 for the bike shed, perfect for small items and still light enough to carry and store away in the shelf when not in use.
Don't need it often, but when, you're in dire need to have that little lathe at hand...
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My biggest regret was not buying the milling head to go with my little lathe. It's been worked hard over the last 40 years and has a few faults now. Originally sold as a model makers lathe. It's earned its keep and doesn't really owe me anything if it falls apart tomorrow.
If you tot up the cost of bits made, it's paid for itself with all the screw cutting and machining.
Wheel spacers, collars, main stand pivot, side stand pivot bolt, engine mounting bolts, caliper bolts, some in high tensile stainless which was pushing things it a bit.
Most useful tool next to the lump hammer and mole grips!
Regards
Dave
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I picked up the carb bodies from the vapour blasters today, they came out as good as expected. here are a few pits remaining , but they can't put metal back on! Bit of a balance between smothing out a few deep pits and not rounding off the sharp edges on the lettering/ keihin logo
Currently removing all the blanking plugs and giving them a buzz in the ultrasonic followed by drying off and a light spray with duck oil to preserve them for now. It will be a few months before I can get the plating done.
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I haven't been slacking though, fuel tap body cleaned up and the brass nut nickel plated
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Regards
Dave
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Making a start on the electroplating. A few test pieces I put through yesterday evening. This is my first time using commercial carriers and brighteners.
This is using the Gateros chemicals. I only put 4ml of brightener in rather than 6 ml as per the instructions hoping for a less shiny finish hoping that would give better adhesion for the yellow passivate. (Which a lot of folk have problems with). I will have to push through some more clear passivate items first to use up some more brightener.
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So far I am degreasing and stripping old plate off using a sodium hydroxide based sink unblocker in the ultrasonic bath followed by warm citric acid until there's no more fizzing. If they are then clean enough (water break test).just a minute in 5% HCl rinse and straight into the bath. A few bits where rust is visible in any pitting, just back into the acid till it's gone.
Prior to passivation, 5 minutes in the ultrasonic using warm soapy water to scrub any residual brighteners from the surface followed by an acid dip.
Regards
Dave
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Looks like you are getting good results there. Nice work!
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Good results are still to come - or not if the yellow passivate on all the carb bits doesn't rub off.
I have a Speedo base to do and hopefully that might use up some of the brightener and dull things down a bit.
Regards
Dave
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Hard to see what's going on in there with all the 'bubble bath' they put in these solutions. It got to the top earlier and had to poke it back down with a plastic stick.
I suppose I should just light a couple of stinky candles and relax until they're done.
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Regards
Dave
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The Gateros kit is really good, its very satisfying when you get good results
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Finally got around to doing the yellow passivate the last few days after struggling with adhesion.
A few words of wisdom for anyone using the Gateros kit especially the brightener.
DO NOT DUMP IN THE MAXIMUM AMOUNT OF BRIGHTENER FROM THE START
Initially I was aiming for a satin like finish more in keeping with the original so opted to add 4ml brightener instead of the recommended 6ml. Things were still coming out the bath looking like chrome and the excess brightener film left on the plated items was making the passivate difficult to adhere. So the only thing for it was to do a couple of large items (Speedo bases) to pull some of the brightener out of the bath.(it gets consumed during plating, occluded within the plate and as a surface film).
To succeed with yellow passivate you only need a satin-dull plate coming out of the bath and even that brightens up after passivation.
The key seems to be getting bubble formation in the acid dip before the passivate. With the bright finish and using 5% HCl there were no bubbles at all even after a good minute in the acid, almost like the brightener film was acting as a lacquer.
With much reduced brightener levels in the tank, cleaning off the brightener film becomes easier and bubbles in the pre passivate acid dip make an appearance much quicker. But you still need to wash it off well. I have currently settled on using a warm detergent wash for about 5 minutes in the ultrasonic bath followed by a long soak in a jug of water. Followed up by a quick buzz using a mildly and dilute alkali degreaser.( 10% dilution of Elbow Grease Heavy Duty Degreaser).
Here's what they come out the bath before passivation
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Here's after passivation
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Other than the initial frustration it seems relatively straight forward but very time consuming.
I did feedback these observations to Dan at Gateros. Very helpful chap who looks after his customers.
Regards
Dave
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Good tips there Dave and nice results. I have one batch of zinc electrolyte which had depleted brightener so I will try that out.
Yes I always find Dan at Gatetos really helpful unlike the guy at Youplate, who wasn't very helpful at all.
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For the barrel spring that closes the throttle and the torsion spring on the carb link rod, how do other people plate these?
Cleaning/pickling , anodic stripping or dunk in acid and prey?
De-brittlement, does any one do this?
And what about the hard steel inserts in the carb sync adjuster screws,
Regards
Dave
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Finally finished the zinc plating.
[attachimg=1]
I have tried to reuse all original components where possible but there were a few screws that had been chewed up and quite rusty.
I was unable to salvage the M5 screws that hold to the top cover onto the carb bodies, so I plated some small head stainless as screws. I used a Woods nickel strike first and then into the zinc bath immediately .
[attachimg=2]
This modern trivalent yellow passivate is not as good as the old hexavalent stuff. Even with the best cleaning between plating and passivation the colour does fade as bit if you rub it hard enough, but then the old stuff did to some extent.
Regards
Dave
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Time to start reassembly, first was to rivet the two halves of the 'wheel' that the throttle cable goes around.
I used M3 x 5mm aluminium rivets and an old form tool that I originally made years ago to rivet the brake disc mudguard onto it's bracket.
Assembly riveted together
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Form tool
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I can now start putting the rack back together
Regards
Dave
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That plating looks very good.👍👍👍
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Had some time this afternoon so I made a start on the rack. I was watering a lot of thirsty agaves in the glasshouse but it got a bit warm. They have waited 5 months for a drink so another day won't make much difference.
First. Refit the 4 nylon shim washers on each end of the bushes that carry the link rod. Hard to know they are there until they fall out during initial cleaning. The felt seals were installed next followed by the retainers. I found it easier to use a nut and bolt with some flat washers to squeeze the retainers back in.
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When assembling the components on the link rod, there are two nylon shim washers that go either side of the 'Wheel'. When you force close the throttle, the wheel needs to move freely until it hits the stop.
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Other than that it's fairly easy to assemble, the torsion spring is a bit fiddly to get it stretched and located on the peg.
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[attach=3]
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Regards
Dave
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Looks like brand new. 👍
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Looks spot on Dave
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Amazing effort, building a set of ‘as new’ carbs out of a pile of leftovers, what great work.
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Made a start on reassembling the carb bodies.
Lifter arms showing the felt retainer, shim,spring and cupped washer.
[attach=1]
No1 done
[attach=2]
It was a bit fiddly getting the fast idle cam installed, trying not to loose the tiny spring and ball bearing that indexes the cam in the choke upen position.
I have hit one snag so far, one of the choke flap rods won't fit. I suspect that it was in a batch of plating where I dozed off and it was plated for over an hour. It will have to be stripped and redone.
Regards
Dave
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A solution to the breather interconnector tubes. The old ones had to be sliced off with a scalpel.
I had some offcuts of viton tube in various sizes (skip find that I thought could come in handy one day) which is a bit soft compared to the originals. Then it came to me, use an outer sleeve of heat shrink to stiffen it up a bit.
Outer sleeve of heat shrink over viton tube
[attachimg=1]
Shrunk over a drill bit to keep it straight
[attachimg=2]
Trimmed to size with a scalpel
[attachimg=3]
Regards
Dave
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Time to make some gasgets for the carb top covers. After a few practice runs using the side of a serial box I was left with some functional but rather ugly gasgets. Even with the smallest of curved nail scissors, cutting the inside radius was never going to be easy.
Below is what I came up with using flexoid gasget paper.
First thing is to mark out the screw holes. I made a 'cookie cutter' the exact size to slip through the actual holes in a top cover to mark their position. I then taped an OEM gasget onto the gasget paper sheet and so that the holes lined up. I was then able to draw around the inside of the OEM gasget.
Using a cookie cutter I could then cut out all of the inside curves and then use a scalpel to cut the straight sections. The large cutter was a roll bar bush collar from a ford Sierra. Been in the 'come in handy box' all this time and it came in handy!
[attachimg=1]
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Next I screwed the top cover to a piece of plywood sandwiching the gasget paper. Then used the cutter to cut out the inside radius on the outside.
[attachimg=3]
Then using a scalpel I was able to cut the remainder of the outside profile using the top cover as a guide
Spot the difference
[attachimg=4]
Regards
Dave
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Time to see if everything fits together after having to strip and replate one of the choke rods and a few screws that ended up over size while I was sleeping on the job. This is just a test fit. Fuel connectors and sync adjusters still need fitting.
Installed the new gasgets on the top covers and just before that I bent over the tab washers on the lifter arms. Shouldn't need to go in there any more. Refitted the choke flaps.
Next job is to sort through the brass ware and see what I have or haven't got. Also need to find the o rings and drain screws for the float bowls. I have tried measuring an OEM o ring and can't decide if it's 63,4 or 5 ? Some advice on how to fit these would be appreciated since they are no longer shaped to fit the bowls. I guess some glue might be needed in strategic places.
For the drain screws I haven't decided whether to try making some or take a punt with those on AliExpress. All comes down to being able to cut the screwdriver slot and make a neat job of it.
Here's where we are at the moment,
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[attach=2]
[attach=3]
Regards
Dave
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Very nice work in detail there.
Hopefully you'll get the deserved running accuracy in response too.
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REet, smart. Nice work.👍.
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63 x 1.8 seems to fit ok
[attach=1]
Regards
Dave
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Drain screws from AliExpress
O ring seat 9 mm, screw head 9.4mm
[attach=1]
[attach=2]
Might work if there's nothing else but doesn't look right. Back to plan b for these.
Regards
Dave
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Fairly sure there was a seller of these on eBay but they weren’t exactly cheap
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The problem with them screws is that there is very little contact area between the screw head and the carb body, essentially a ring 0.2 mm around the screw head making contact and no friction as you tighten them which in the wrong hands could easily result in stripped threads or them working loose.
A heads up for anyone else thinking of buying these, check that the head diameter 12mm. I didn't loose much with these ay £3.50 for 2 , I just added a couple onto an existing order get above the free postage threshold.
NRP have the Keyster ones back in stock now at just over a fiver each. Might have to bite the bullet. I'll hold off for now until I have sorted through all the spare brassware to see what else I might need.
Does anyone have any good tips for cutting neat screw slots, I have seen something somewhere about folk grinding the set off a hacksaw blade to get the right thickness? Machining the threads and holes be easy enough and I have enough round brass bar laying around.
Regards
Dave
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The problem with them screws is that there is very little contact area between the screw head and the carb body, essentially a ring 0.2 mm around the screw head making contact and no friction as you tighten them which in the wrong hands could easily result in stripped threads or them working loose.
A heads up for anyone else thinking of buying these, check that the head diameter 12mm. I didn't loose much with these ay £3.50 for 2 , I just added a couple onto an existing order get above the free postage threshold.
NRP have the Keyster ones back in stock now at just over a fiver each. Might have to bite the bullet. I'll hold off for now until I have sorted through all the spare brassware to see what else I might need.
Does anyone have any good tips for cutting neat screw slots, I have seen something somewhere about folk grinding the set off a hacksaw blade to get the right thickness? Machining the threads and holes be easy enough and I have enough round brass bar laying around.
Regards
Dave
Something like this https://www.ebay.co.uk/itm/336154261880 available in 0.5mm thickness, but would need rudimentary mount to drill etc and some method of holding brass bar and moving across this, thinking lathe cross slide and dremel ?
A woodworking mortise hand saw will cut brass more accurately than trying to hold a hacksaw blade straight enough, could be utilised.
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I have slitting saw, but at the moment I'm only set up to mount it on an arbour between centers and used to cut hexagon on the end of round bar held in the tool post. I might need someway to get up/down movement. I could just cut the slot to limited depth which would be curved same as the saw radius and then just flatten out the slot with small file.
Dave.
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I decided to have a go making the drain screws and had a practice run this morning. Here's what came out of the garage.
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The OEM screw is the tarnished one with screwdriver marks in the slot.
A little refining of methodology and it should be doable. The first mistake was in cutting the screws slot and then facing off the screw. It caused the tool to jump a bit. Second was removing one thread too many closest to the screw head.
The 1 mm drill bit was a bit blunt after using it on fibre glass PCB material so I picked up a couple of new ones this morning.
Regards
Dave
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That looks just great Dave! Have you tried it in the carb float bowl?
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That looks just great Dave! Have you tried it in the carb float bowl?
Short answer - doesn't fit
Long answer - the old knackered carbon steel die I found lying around is giving me an oversized thread.
This was a run through to make sure I had the necessary tooling and holders. I'm sure with a decent die and a regrind of the lathe tool to give a smoother finish on the underside of the screw head it will be ok.
Regards
Dave
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Nice aesthetic in that though, which will make a good replacement when small issues, mentioned above, are resolved.
Does anyone else find that you need a unusually large flat blade screwdriver to engage them properly, and not just twist them in middle of slot that leads to "camming" out along with that subsequent mushing of the slot ?
Also need one with very good condition "grind" and flat end to let it engage fully and deep into slot.
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I have a big flat blade screwdriver intended for electricians that usually gives a snug fit. The trick is not to overtighten them in the first place.
But you're right if some monkey uses a too small too thin driver the slots get chewed.
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Were you aware that there is a Honda special tool for the clutch adjuster on the 500-4 Nige. The big slotted thing in the drive chain cover. Might also fit the drain screws, never tried it but seem to recall it’s a multi bladed tool
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Were you aware that there is a Honda special tool for the clutch adjuster on the 500-4 Nige. The big slotted thing in the drive chain cover. Might also fit the drain screws, never tried it but seem to recall it’s a multi bladed tool
I was much more involved with the 750s Ken, and so not familiar with that tool. Sounds like it could be good for this though.
My own method is a great big woodworking screwdriver that my dad used to drive in big brass hinge screws by hand (before electric tools were invented ;D )not sure, but either Stanley or Marple brand, the type with see through yellow resin handles for properly leaning into the job in door hanging.
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New m6x0.75 die arrived so on with making the drain screws. First job was making a jig for the through holes.
It screws onto the screw.
[attachimg=1]
Turn down a blank screw ready for threading. The undercut around the cross holes is 5 mm dia to match the root size of the thread in the float bowl.
[attachimg=2]
Add the thread and drill the through holes. I used my PCB drill for the cross holes using a 1mm bit. Important to get the length of the screw exact at this point.
[attachimg=3]
Saw of the screw and rough face off leaving a small pimple in the center. This is to center the slotting saw. The hole was slotted using a slotting saw mounted on a arbour and the screw mounted in a jig on the tool post. It does mean that the screw slot is slightly curved matching the diameter of the saw but it's not noticeable.
[attachimg=4]
Once slotted face off and polish. The screw is screwed into the holder to do the finishing cuts and something to hold onto while polishing.
[attachimg=5]
One issue that emerged was the female thread in the float bowl was slightly tapered, they hadn't gone all the way through with a straight tap so any over size on the screw length would tighten up before the head bottomed out on the recess on the float bowl.
Regards
Dave
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That’s a great job on these drain screws. Looks the business.
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Slowly getting around to final assembly and making a start on sorting through a pile of brass ware, in particular the needles and emulsion tubes.
All of the needles I could find all measure the same at the top near the circlip where the needle is parallel and not tapered.
Then just dropping the needle into the tube and seeing how far it falls in.
[attachimg=1]
So top to bottom, all keihin needles
Good
Good
Good
Not so good
Really bad
With the good ones, the bottom groove lined up with the face of the oraface. Worn tubes allow the needle to drop in further. Swapping needles around makes no difference.
A lot of folk still maintain that original parts reused are a better option than Keyster replacements, from experience, I don't agree with that unless you are paying attention to any possible wear on the inside of the tube at the top. It's not obvious just by looking at them. The needles seem ok though. Ignore this and spend the next few months chasing rich running and sooty plugs.
I think wear to some extent depends on riding style, scratching around back lanes or urban traffic is probably going to impart more wear than constant throttle on a motorway.
Anyway, we have touched on this topic off an on, at least since I have been a member on here, so I thought about posting the evidence for the next person that comes across this issue.
Regards
Dave
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Hi Dave, thats in interesting way of doing it with the emulsion tubes, that my find the problem with my 550f rich running
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I'm wondering why the bottom 2 needles only appear to have 3 grooves whereas the others have 5. The bottom needle point also doesn't look like a Keihin needle, too blunt and wide.
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I'm wondering why the bottom 2 needles only appear to have 3 grooves whereas the others have 5. The bottom needle point also doesn't look like a Keihin needle, too blunt and wide.
They have disappeared into the emulsion tube because the hole is enlarged.
[attachimg=1]
Regards
Dave
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I can't say this trick will work for all keihin but it does for the 400f
The two bad ones were responsible for black plugs in 2010 when I rebuilt the carbs after they got gummed up while laid up for a couple of years. At the time I replaced them with genuine parts and the problem went away. All other brass ware had already been replaced with genuine honda bits, the tubes and needles weren't in the rebuild kit so you had to buy them as a separate needle set.
Regards
Dave
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Good inspection and detail in appraisal.
Some interesting and relevant findings too.
Speculation on wear of emulsion tubes, I feel it is unusual in pure ability to "cut" or wear the emulsion tube with the needle as the periphery moves away from the needle with wear occurring, which in metal machining usually stops the cutting happening. Something clearly going on there, but a little of a mystery in trying to think exactly how it happens.
Certainly food for thought.
Wondering if there's any ovality to the wear or is it circular ? Could it even be seen in that size though ?
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There is no ovality on the needles, which is why I suspect corrosion has had a hand in what happened. Looking at the outside of the tubes there isn't any corrosion/putting that would set off alarm bells, hence why I originally reused them in 2010.
Fortunately the 'come in handy box' delivered and I have 6 good tubes to play with.
Regards
Dave
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I happen to have a bag in front of my keyboard full off all the brass out of a set of 550 carbs. So I thought I'd try this and see what the result was.
Completely different. None of the needles went down fully, in fact they stopped well before the grooves, plus even in that position they were really protruding past the end of the emulsion tubes. It seems the 500/550 needles are considerably longer than the 400s. You'd expect they'd be similar, same style of carb so why are the 400 needles so short? How do they interact with the main jet when they don't protrude past the end of the tube. Have you checked the number stamped on them to see if they are standard? maybe someone swapped them in the past out of a different Honda.
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I have about 8 of them, the good 4 were run in the bike when diagnosing the original problem. I then bought 4 honda needle sets (they were reasonably priced at that time)and installed them. They were all the same length/taper. The good 4 came from a wrecked bike that I bought for spares in 1987. The carbs hadn't been messed with apart from chewed up drain screws.
I can't see any keihin logo on either the tubes or needles. The needles have 18234 etched around the top just below the circlip groove.
Regards
Dave
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[attach=1]
Looking at Keyster documentation they have 18234 annotated next to their D22-S(standard) needle which might be a clue.
Regards
Dave
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On the web they reckon the standard needles as fitted by Honda were marked D22. As in all things that's subject to be wrong. Shame I can't find the same tables the 500/550 has for all there markings.
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D22 is the Keyster part number.
Here for the 550
https://www.jp-stores.com/mc/we70630/?c=329&show=20&mode=&keyword=&p=1
I have never found a better resolution image for these kits
Dave
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When setting float heights, honda doc's always shows a round bottom float so it's obvious where to measure from The 400 has flat bottom floats, so should we measure from the highest point or the middle? Maybe a dumb question but someone has to ask it.
Not knowing I have always gone middle before to edge my bets on previous builds
Regards
Dave
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Another kind of question regarding the small black bits that hold the float valve bodies in place.
[attachimg=1]
The clip is slightly curved, they all are. The above image is one resting on a bit of tool steel.
My assumption is that it acts as a dished washer and the prongs bear down on the center of the valve body to keep it in alignment rather than on the edge off center. Installing it wrong way up could result in the valve body not sitting straight in the carb body. Does this make sense?
Regards
Dave
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I always took as keeping pressure on the brass
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Final assembly completed
Installed all the brass ware, throttle sync adjusters and fuel interconnectors.
Carried out a bench sync
Set the float heights. A couple of floats were not sitting right on a flat surface so they were straightened first
[attachimg=1]
A bit of work to do here looking down the line of floats. Swapping floats can even things up a bit before adjustment.
Using my float guage set at 21mm. It was still in the box of bits so that saved making another one.
[attachimg=2]
Final check using the Vernier calipers
[attachimg=3]
Just need to source some tubing for overflow and breather and we should be good to go.
For interest, here are the o ring sizes I used. IDxCS
Float valve 5.5 x 1.5
Main 4.1 x1.2
Fuel interconnects 6 x 2
Bowl 63.2 x 1.9
Drain screw 5 x 1.8
Regards
Dave