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rebuilding carbs
Oddjob:
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
K2-K6:
--- Quote from: Oddjob on May 14, 2026, 09:00:59 PM ---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
--- End quote ---
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.
exvalvesetdabbler:
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.
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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.
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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.
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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.
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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.
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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
Johnny4428:
That’s a great job on these drain screws. Looks the business.
exvalvesetdabbler:
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.
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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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