CB550 Tuning Advice

[K2-K6]

At this point tge zim is to make sure you feel got fuel supply free from chunks  and the idle jets plus side passages flow cleanly as they should.

It should be useful to run the airscrews at just one turn without the airbox in place, but only for that reason temporarily.  What you're looking for is start and warm, gradually retracting choke until it'll run at idle without interference.   Essentially its establishing if the idle circuit are clean and functional. Then it can be moved onto fully installed intake and should respond logically to fine adjustment with that all in place.

Likely it won't respond to "snap" throttle opening well, or if you tried to ride it and ask for productive torque.

[Sesman]

Thanks for the fuel line tips. I sourced from Honda classics in the end. We shall see.

[Sesman]

Oh and thanks for the offer, Ken. Unfortunately I’d purchased the replacement yesterday and didn’t see your response until this morning. 🤨

[Sesman]

Mmm. So I sourced some hose from Honda Classics and it’s arrived very promptly. It’s marked AFS NT 006 DIN 73379 Type C1 NBR. If I’m not mistaken this is a nitrile specification. I appreciate not all specifications are equal, but it will be interesting to see if this is any more resilient to deterioration than the shite I purchased from another supplier.

Here goes nothing, but I can’t help thinking a viton specification tube will remove all doubt regarding hose break down creating crumb deposits in the fuel line.

[Oddjob]

NBR is the classification of nitrile. I thought it was described as viton? I would imagine it will be affected by ethanol and cause problems.

[Neilw]

Mmm. So I sourced some hose from Honda Classics and it’s arrived very promptly. It’s marked AFS NT 006 DIN 73379 Type C1 NBR. If I’m not mistaken this is a nitrile specification. I appreciate not all specifications are equal, but it will be interesting to see if this is any more resilient to deterioration than the shite I purchased from another supplier.

Here goes nothing, but I can’t help thinking a viton specification tube will remove all doubt regarding hose break down creating crumb deposits in the fuel line.

I've purchased the same stuff, based on the description on the website which states

 "Fuel Line Tube Pipe of 5.5mm Bore (10mm outer diameter) for this model and many others with 5.5mm bore fuel line fitting. This tube is the latest Ethanol Resistant rubber material suitable for all types of E5/E10 fuel. "

Hmmm if it says "DIN 73379 Type C1" on it, then according to Chat GBT it's not going to be good enough.

Recommends - FKM / Viton (or DIN 73379 Type E)   Highly Recommended. FKM is fully immune to ethanol degradation and outlasts NBR by decades.
Or
DIN 73379 Type 2E or 3E (if using NBR)   If you stick to NBR, ensure it is rated for E10/E85 fuels (bio-fuel resistant). Standard older C1 NBR will fail.

[Oddjob]

I looked it up.

AFS NT 006 DIN 73379 Type C1 NBR fuel hose is not highly ethanol-resistant. While it is rated as compatible with standard commercial unleaded petrol containing up to 10% ethanol (E10), it is not suitable for high-ethanol blends like E85 or E100.

So seems to be OK ish with todays fuel BUT maybe not so much with any future fuel as there are rumours the ethanol content will be increased in line with the rest of the world, namely America where I believe it's much higher. They do seem to making it out to be viton in their description, what else would you think?

[Neilw]

Mmm. So I sourced some hose from Honda Classics and it’s arrived very promptly. It’s marked AFS NT 006 DIN 73379 Type C1 NBR. If I’m not mistaken this is a nitrile specification. I appreciate not all specifications are equal, but it will be interesting to see if this is any more resilient to deterioration than the shite I purchased from another supplier.

Here goes nothing, but I can’t help thinking a viton specification tube will remove all doubt regarding hose break down creating crumb deposits in the fuel line.

I've just received mine and its marked up the same. It's exactly the same tube i was using that has shed into the carbs, right down to the lettering. i'm going to send mine back and try to find something that guarantees it's safe and won't shed. Modern bikes must use something

[Oddjob]

If you can find some marked DIN 73379 Type 3E that’s lined with FKM which is viton and 100% ethanol resistant.

[McCabe-Thiele (Ted)]

Gates Barricade petrol pipe is ethanol resistant to E85.

[Oddjob]

But they don't do 5.5mm ID fuel line AFAIK Ted.

[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

[McCabe-Thiele (Ted)]

It will be a tight fit where the petrol pipe passes through the carb bracket arrangement.

My Gates pipe (reinforced) is 11.7 mm o/d 6.0 mm size printed on the pipe,  it fitted just fine, I always use a pipe clip as well.

Looks a pretty good price. Gates don't seem to go into as much detail as this Coline does.

[Oddjob]

There is viton lined 5.5mm fuel line around with 6.00mm od. Not cheap though at around £26 a metre.