Topic: How do you route YOUR fuel lines?

[Scott S]

 1971 CB500

 Show me how you route the fuel lines on your CB500. I have mine running through the holes on the stay plate. The problem is, when I mount two inline fuel filters, it gets way crowded in there. If I try to go straight to the barb on the petcock, at least one line gets kinked (usually the left side). I have them looped all around the manifolds, etc., but the hose for the left two carbs has air in the lines.

 I'd really prefer to run the inline filters, but does that mean I can't go through the stay plate? Maybe turn the barbs down, run filters under the carbs and have a straighter shot up to the petcock?

[TwoTired]

If your fuel tap filter is working properly, why do you need inline filters?  (Honda didn't think they were needed.)

If two (or three) filters work better than one, then why not add six or eight filters?  Just think how much cleaner your gas will be?

When I get a bike with inline filters jury rigged onto a bike.  I remove them, and then repair or replace the Honda filter, which has served well for over 30 years.
No fuel line routing problems.

Cheers,

[Duke McDukiedook]

I say try three inline filters, three is the magic number. 

[nancy]

To be fair - Honda possibly didn't fit inline fuel filters as they were assembling a new product - not dealing with a 30+ year old tank with contaminants.

[Lenny55]

There is no good way to run inline fuel filters on a '73 500, IMO.  I tried and tried and ended up with the same kink.  Wasted time and money on a few different filters with the same result.

In the end I took the the tank to a rad shop that was recommended to me by the shop I deal with.  They cleaned and lined the tank with redkote for $100.  A little steep maybe, but they know what they're doing and I didn't have to deal with all the chemicals.  While that was curing, I ordered up the petcock internals from the local Honda dealer.  They were about 30 bucks or so.  The old screen had a big tear in it by the way.

Anyway, haven't had any problems with little rusty bits since.  Not sure what your financial situation is, but it was money well spent.

Lenny.

[OldSchool_IsCool]

I removed the Honda in-line filter because I installed two in line filters under the tank.
Why everyone thinks Honda Engineers have figured everything out is a myth. I'm
totally convinced that after removing Honda's funky in line tank filter my bike runs better.
Hey 34 years of varnish to plug the existing filter screen holes has to be considered a restriction.
I have had the same problem in my NC50 mopeds.

An in-tank filter that lasts 30+ years or in-line filters that last maybe 2 seasons.  Who's the smart ones?

[brianzenk]

good point ! If only the Honda Engineers had figured out how to keep rubber from rotting.

[TwoTired]

To be fair - Honda possibly didn't fit inline fuel filters as they were assembling a new product - not dealing with a 30+ year old tank with contaminants.

What is fair about routinely operating with defective equipment?

Anyway, it is not unusual or difficult to restore the tank to a clean internal state.  It does take a bit more effort than applying a band-aid, though.

Basically, if your tank is the source of contaminants, fix the problem at the source.  A filter is supposed to deal with unusual events, not routine ones.

If your oil supply is dirty, do you just change the filter?  

Honda did put a filter on the bike to handle aberrant events.  It works quite well.  They probably didn't use in-lines because they are inferior and need periodic attention/replacement.  They also make fuel line routing complex, and often interfere with the gravity feed system design.

[TwoTired]

Why everyone thinks Honda Engineers have figured everything out is a myth.  I'm
totally convinced that after removing Honda's funky in line tank filter my bike runs better.

Why anyone thinks they know more than the Honda engineers is not only a myth, but profound arrogance in most cases.

Also, being personally "totally convinced" is not really very convincing in the absence of quantifiable data.  And, "better" doesn't qualify as quantifiable.

[Spanner 1]

One caviat tho'.... Honda did not design for rusty tanks 30 plus years later !.... I didn't think I could save my very rusty Candy Gold '70 tank, but I proved myself wrong and 'only' have a stock filter.... no liner either!

[Scott S]

 I have several petcocks from CB500 tanks. The only filter is the screen in the petcock. None of them have (had?) a filter or screen or sock on the pick-up tube. Is there supposed to be one or are you saying the screen in the petcock is enough?

[TwoTired]

I have several petcocks from CB500 tanks. The only filter is the screen in the petcock. None of them have (had?) a filter or screen or sock on the pick-up tube. Is there supposed to be one or are you saying the screen in the petcock is enough?

The proper screen in the fuel selector doesn't let anything through that can't get through the #40 slow jet orifice, which is the smallest orifice in the carb.

My 74 Cb550 has the same fuel valve, filter screen and sediment bowl as the Cb500s have no internal sock.

The only problem I've encountered is if you have rust in the tank and let the bike sit with tiny rust specks in the carb bowls.  The specks will then lock together to form bigger ones that will lodge in the slow jets.  They usually fall out again when you stop the engine, making an intermittent problem.  That can be solved by simply draining/flushing the carb bowls.  And clearing the sediment bowl.  Then all is good until you let the bike sit without running for a while (and having rust in the rank).

If you do have rust specs that are trapped by an inline filter, at some point the filter become clogged/restrictive.  Left to accumulate particles, eventually the carb fuel level is impeded, leaning the engine, and giving performance issues.  Also, air bubbles in the filter impede the free flow of gravity fed fuel flow ans they try to rise to the fuel level surface.  This is most severe when there is low head pressure from the tank (low fuel level).

Honda changed the filter scheme, I think the eliminate the sediment bowl maintenance requirement.  The in-tank sock is washed by the sloshing fuel.  Sediment stays in the tank but doesn't seem to effect fuel flow.

Of course, if the system is abused it will fail.  If fuel varnish is allowed to dry on the sock, the system is damaged.  But, Honda didn't make these bike to sit long enough to allow all the fuel to evaporate out of the gas tank.  I think that sort of neglect is abuse, personally.  And, I don't fault the design in such instances.  IMO.

Cheers,

[Gordon]

You can route your fuel lines with the in-line filters straight down from the petcock and then back up to the fuel inlets, which will be pointing downward in this configuration.  At least that's how I have them routed on my 750. 

There's no problems with air getting trapped as long as you don't have any bends that go up and then back down. 

[Deltarider]

After experimenting with inline filters decades ago (resulting in nothing but problems) I'm happy again with the genuine intank filter. It's like TT says: the filter is capable of catching all particles that can endanger flow and extra filters dont 'make sense.
Important: have the fuel lines cut to the original length: 17 and 28 mm resp. Best ID is 5,5 mm. As a result you can't go wrong with routing and thus no kinking.

[Gordon]

I'll just leave this here...

However, if for some reason, one is not able or willing to fix or repair the intank or petcock type of fuel filter, in-lines are the next best thing, if sized correctly, and implemented compatibly with gravity feed systems.

[Scott S]

 I also saw mentioned in one thread that the left pair of carbs goes to the forward barb on the petcock. Is there a reason for this? Aren't both barbs fed equally?

[haill]

does a petcock with a filter sock for a 74 model cb550 gas tank fit in a 71 to 73 cb500 gas tank?

[TwoTired]

I also saw mentioned in one thread that the left pair of carbs goes to the forward barb on the petcock. Is there a reason for this? Aren't both barbs fed equally?

Routing order is indifferent.  When you run low on gas, the barb farthest from the valve starves those carbs first.

[TwoTired]

does a petcock with a filter sock for a 74 model cb550 gas tank fit in a 71 to 73 cb500 gas tank?

No.  The 74 tanks have the same selector/filter arrangement as the 500s.  If you want the internal sock you must get a 75-76 tank. (For US models)

[brianzenk]

http://www.thinkingmanagers.com/management/japanese-business-culture.php

[brianzenk]

Fuel line and Visu-filters

[Gordon]

Fuel line and Visu-filters

I was thoroughly confused until I realized that picture is sideways.

I see at least one possible issue with that routing.  Air can get trapped in that upward bend before the top filter. 

[brianzenk]

Sorry about the sideways picture and confusion. There is not alot of room in that area.
Here is another picture at another view.

[Gordon]

Is that an original Rube Goldberg design?

I definitely see an issue with that one bend that goes up and then back down right before the filter. 

[75cb550 (kyle)]

i like to see the fuel level in my filter... can help when diagnosing running issues... on my original tank i had a running issue. turns out i wasnt getting fuel and had not even thought to check that... if i had an inline filter, would have seen it.

= my .02