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CB550 Tuning Advice
Neilw:
I've got to the bottom of where the bits of rubber were coming from.
I cut the hoses open, and there was no sign of rubber deterioration. So that's good news for everyone buying replacement hoses!
So I turned my attention to the other rubber bits in the cabs, the O-rings and seals, which were new a few months ago. I scanned through them all, and I found the O-rings on some of the jets, the petrol feed connector between the cabs, and the float bowl drain screw had pinches, small nicks, and flaky rubber. This is the source of the contamination, and I think it was self-inflicted, in that i may have used wd40 to lubricate some of them, dry-fitted some and on others may have used silicone- I just can't remember, but I was definitely the cause.
Thanks to NuseJulie for helping me diagnose what i found and also supplying me with some replacements.
I hope others can learn from my mistake - see pics.
NB: the damage on the jets was caused by me removing them using pliers; the actual jet is fine.
Julie also spotted I have 100 jets installed rather than the 98s. I do have a Motoad 4-into-1 aftermarket exhaust on the bike (everything else is standard) and wonder if this is the reason they were changed. I can't find any 98's to replace them, so I may have to stick with the '100s for the foreseeable future!
Oddjob:
Any idea where you sourced the orings from in the first place?. Most sellers these days are providing Viton rings and for them to disintegrate like that looks like they supplied Nitrile ones instead. Plus I've not really seen any damaged by fitment on the t pieces, not that much anyway which makes me think that maybe they provided the wrong size rings in the first place. I've never had to use any lube on the t piece ones, maybe a little on the main jet, especially if it's not an original Honda ring, most sellers these days can't provide the exact size needed as they need to be specially made in batches of 500 so they opt for a close size and live in hope. I've had them so I had to tap the jet down to get the ring to compress, not ideal if the tunnel it fits in is already showing corrosion damage.
Oddjob:
As for the fuel pipe. I personally think sourcing the Viton lined pipe now is a better solution. The present pipe everyone seems to be using is only rated to withstand E10 fuels. When, and I believe it is a when, they increase the Ethanol content in petrol the present lines may start to suffer. Far better to fit it once and have peace of mind. It's not like it's an easy job to do so the less you need to muck with the carbs the better. Yes it's more expensive but I think it's more forward thinking so worth the little extra.
Neilw:
--- Quote from: Oddjob on October 16, 2026, 04:02:59 PM ---Any idea where you sourced the orings from in the first place?. Most sellers these days are providing Viton rings and for them to disintegrate like that looks like they supplied Nitrile ones instead. Plus I've not really seen any damaged by fitment on the t pieces, not that much anyway which makes me think that maybe they provided the wrong size rings in the first place. I've never had to use any lube on the t piece ones, maybe a little on the main jet, especially if it's not an original Honda ring, most sellers these days can't provide the exact size needed as they need to be specially made in batches of 500 so they opt for a close size and live in hope. I've had them so I had to tap the jet down to get the ring to compress, not ideal if the tunnel it fits in is already showing corrosion damage.
--- End quote ---
I got them from NurseJulie, and was supplied the correct ones, the same that 1000's of customers have used in the past without problems. Trust me, I've made so many mistakes; it's just another one to add to the list of life lessons lol.
Neilw:
--- Quote from: Oddjob on October 16, 2026, 04:20:21 PM ---As for the fuel pipe. I personally think sourcing the Viton lined pipe now is a better solution. The present pipe everyone seems to be using is only rated to withstand E10 fuels. When, and I believe it is a when, they increase the Ethanol content in petrol the present lines may start to suffer. Far better to fit it once and have peace of mind. It's not like it's an easy job to do so the less you need to muck with the carbs the better. Yes it's more expensive but I think it's more forward thinking so worth the little extra.
--- End quote ---
That's my plan!
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