SOHC.co.uk Forums > Project Board
1978 Honda CB550 Supersport - My first retro bike rolling restoration!
woody928:
--- Quote from: Oddjob on June 14, 2020, 11:25:45 PM ---Where to start ;D ;D
98 mains and 38 pilot jets are correct for a 550F.
I presume you've ordered a set of Viton O-Rings for the carbs, they'll need Viton because the new fuel has Ethanol in it and the old style O-Rings really don't like Ethanol. Julie on here sells the kits. She also sells the figure 8 links for the vacuum adjusters.
Whoever put all that black gunk all over the main jet clearly did that because the O-Ring actually holds it in place, as they age they shrink and thus the jet starts to drop out, stupid really but it it what it is, you'll need a new main jet, shame as I just sold a set of 98 mains I'd had for years and years. According to Honda the clip on the needle should be on number 2. However they fail to say from the top or the bottom but I'd imagine it was the top. If so those are correct. Can't remember now what size those screws are holding the needle in place, might be 3mm, might even be 2mm. Have you measured one?
I've used these clips with good results,
https://www.stainlessmiddleton.co.uk/34313-hose-clamps
Extra narrow 31-51mm. Not the cheapest but really nice looking clamps, you want them tight but not too tight.
If your replacing the hoses you'll need Vitrile hosing. Just bought some for my carbs so I'll look what sizes I bought etc and let you know.
How far you go to restoring the carbs is up to you. Doing a really good job involves have some of the parts BZP plated, these include the butterfly and connecting rod etc, all the choke linkages, springs etc. Takes time and a little money and a whole lot of patience and effort but looks really nice after.
--- End quote ---
Hahaha I do have just a couple of questions... :-[
Thanks for confirming Ken. I have already got the Viton O-Ring kit from Julie, when you say the figure of eight links are you referring to these bits as pictured below? if so then that would be mega to replace both!
IMG_8062 by Mark Woodrow, on Flickr
Just my luck that you've only just sold them! Right that makes a lot of sense, there's clearly been a bit of bodging along the way. They clearly made some efforts at fixing items such as re-tapping some of the float bowl holes... I would agree from what I've seen that they were correctly fitted per the factory settings, which is reassuring. I measured and the screws are M3 - 10mm screws, I'm trying to get stainless replacements for the lot of them from my contact.
Thanks for the heads up, I'll keep it saved for future reference. I actually ordered some black stainless ones which are 30-45mm which I hope will fit and be very subtle and not blingy compared with bright new stainless items. I'll wait and see.
Many thanks on the hose front, I now think the main hose has an internal diameter of 5.5mm and the smaller 3.2mm but not 100%. Shame about all the ethanol that's going into the fuel these days!
I must confess I'm not a huge fan of the whole pimped up zinc factory finish on various metal components. I know its OEM however if I was going all out then I'd just get the lot vapour blasted, I think that comes up amazing. That said, this is very much a functional rebuild rather than looking to build a show bike so I've taken them cosmetically as far as they need to go for me, for now. I just would really like them to operate smoothly and as intended so that the engine operates correctly.
--- Quote from: K2-K6 on June 15, 2020, 02:14:27 PM ---Seems that currently the view is that original Kiehin jets are simply more accurate than alternative replacements. Which is highly desirable for such fine metering these carbs have to do.
If the main jet is just one that has the outside a bit tatty it would be worth filing off the sharp burr and using that with new o-rings, as oddjob indicates, to get a full working set.
The damage hasn't impacted the critical surfaces as far as I can see from your pictures.
Nice work so far, it'll definitely pay off when running again.
--- End quote ---
Thanks for the insight, it's a shame you can't get the same quality these days. I've cleaned all of the components in the ultrasonic for 30 mins and in the case of the brass components, polished them up with the dremel so they're smooth, and blasted compressed air through to clear them. I feel they're as good as they can be now.
That's the only one that I noted with visible damage, I may have a go at cleaning it up in that case. I presume the critical parts are the central hole in the jet itself and the O ring mounts to seal the jet in correctly? So I can afford to lose a little bit of material where the damage is?
Thanks I'm certainly keeping my fingers crossed!
For reference I've called around everywhere I can think of today and I cannot find anyone selling 98 main jets to replace it with anyway so it looks like I have very little choice but to try and repair the one I have.
Bryanj:
Ken you can get 95's from siriusconic in Canada but you gotta search for them their web search is naff, think i found them under 550
K2-K6:
"That's the only one that I noted with visible damage, I may have a go at cleaning it up in that case. I presume the critical parts are the central hole in the jet itself and the O ring mounts to seal the jet in correctly? So I can afford to lose a little bit of material where the damage is? "
Yes as you describe, the o-ring keeps them in place and prevents any unmetered fuel from bypassing the jet orifice. The burr area is ordinarily not touching much so plays no real part in their accuracy unless so severely impaired they'd not locate perpendicular to the casting.
If you struggle for any particular stainless bolts, AHC on the old A30 in Camberley will usually hold stock of most items individually. You can park in the road adjacent to there as it's restricted out front of shop.
Rob62:
Proper job cornish IPA aldi special......my current tipple of choice 8)
sye:
Take a look here for #98 main jet:
https://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-carburetor-parts-keihin-cv-secondary-jet-98-026-051.html
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