CB550 Tuning Advice

[Nurse Julie]

Doesn't Nurse Julie has the right tube?

I don't stock fuel pipe Delta. We've always use the Nitrile pipe from Planet Silicone on all our own bikes and restorations. It was fitted to my 500 K1 5 years ago, and the 750 K6 10 years ago and it's still fine.
https://www.ebay.co.uk/itm/130740225601?itmmeta=01M4Z8QJ12VC40M7NPAQCX37YC&hash=item1e70b98641:g:ITQAAOxyOalTX6Br

[Sesman]

Looks like something has changed, Julie.

This is the stuff I bought and it failed in short order!

[florence]

as I keep my bike outside, the biggest problem I have is with UV light.  I have hose with cloth exterior but at the point where it joins anything such as the tap, it cracks up within a few months.

Some will say the obvious answer would be to keep the bike indoors but that is not a possibility, it has to sit in an archway.  Sometimes a tarp is thrown over the bike.

I would rather find a UV and Ethanol resilient hose.

[Neilw]

Looks like something has changed, Julie.

This is the stuff I bought and it failed in short order!

Same for me.

[Neilw]

I've found DIN 73379 Type 3E, which appears to be bulletproof. It has an ID of 5.5mm but an OD of 11.5 mm. It's also reinforced.

Will this fit?

https://www.carbuilder.com/products/ethanol-proof-fuel-hose-6mm-14

I've ordered a meter of this; I'll let you all know about the fit.

[McCabe-Thiele (Ted)]

I would rather find a UV and Ethanol resilient hose.

I used 303 Aerospace Protector Spray to stop uV degradation of a Hot Tub Vinyl Cover when we had one. It worked well. Used it for 10 years, it does not dry it acts as an effective barrier. Not cheap, lasts ages, effective.

You could just spray the hose where it's exposed to light.

[Sesman]

NeilW.

Just for clarity, you tried two suppliers: Honda classics and planet silicon, receiving the same unsuitable product?

[Neilw]

NeilW.

Just for clarity, you tried two suppliers: Honda classics and Planet Silicon, receiving the same unsuitable product?

Yes, the same; they look identical. I'm just not prepared to take the chance; when the new one arrives, I'll cut the existing ones up to see where the issue is. It could also be the little 3.5/7.5 hoses that connect 2 carbs together (I got these from  Planet Silicon too). I definitely need to see which hose(s) are responsible.

I should say that I haven't tried the Honda Classics one; I'm too scared!

[Oddjob]

It won't be the connecting tubes, they move air only unless the bike goes over. They are just there to ensure equal pressures in the float chambers.

This is what I found on EBay. Viton lined.

https://www.ebay.co.uk/itm/260815755996?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20250417133222%26meid%3D31ec5560b8bf43c8aaee0c7a4ec92eb4%26pid%3D102727%26rk%3D1%26rkt%3D1%26mehot%3Dnone%26itm%3D260815755996%26pmt%3D1%26noa%3D1%26pg%3D4375194%26algv%3DWatchlistVariantWithPSItemDR_BP&_trksid=p4375194.c102727.m162921

[Neilw]

It won't be the connecting tubes, they move air only unless the bike goes over. They are just there to ensure equal pressures in the float chambers.

This is what I found on EBay. Viton lined.

https://www.ebay.co.uk/itm/260815755996?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20250417133222%26meid%3D31ec5560b8bf43c8aaee0c7a4ec92eb4%26pid%3D102727%26rk%3D1%26rkt%3D1%26mehot%3Dnone%26itm%3D260815755996%26pmt%3D1%26noa%3D1%26pg%3D4375194%26algv%3DWatchlistVariantWithPSItemDR_BP&_trksid=p4375194.c102727.m162921

Looks like the same as i have ordered, mine was a bit cheaper - but same stuff.

Good to know about the connecting tubes. Thank you.

[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]

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.

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]

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.

That's my plan!