Cb550f blowing main fuse

[Oddjob]

Yeah, I knew it was different lug shape but thought it was both sides. I bow to your knowledge on this as I don't have an F2 to compare it too.

[Towsejames]

Look at the blown fuse and is it

1 melted in the middle with visible"blobs"

2detached at one end and "floating

It looks blown in half to me, but the replacement which blew right outside my house doesn’t look blown at all despite it definitely being blown. It even has continuity but when ignition is switched on drops volts - I’m guessing it’s slightly touching until load is going through it


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[Towsejames]

Something odd here. The first pic is confusing. The tank looks like a 550K3 but the side panel badges are off a 550K0-2 not a K3. Totally different. Plus IIRC the 550F has one upper mounting lug going vertical and yours are both horizontal  The brake pedal is off a 550F, the 550K has a round tubular type. The clocks are blue faced, so either a 550F2 or a 550K3. The shape of the footrest brackets may clear it up as they are different IIRC between the 550K and the 550F. If the headlight was blowing the fuse why not the 7a fuse? try removing the headlight itself and run without it, see if it blows when the lights are on. If it doesn't suspect the lamp itself, if it does it's a wiring problem on the lighting circuit.

You’re completely right. The bike is a complete mix of 550k3 and 550f parts. The frame is and f but the tank and side panels are k3. I quite like that it’s all made up.


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[Towsejames]

Thank you for all the replies and knowledge. I’ve been busy at work but did get to have a look.

I have since removed the original fuse box which was a mess of bad soldering and green wires. I have fitted a blade type fuse box now with space for spares and retained the original wiring which looked in good condition and crimped spade connectors to fit on the new fuse box. I then traced most of the main loom back which needed tidying up anyway. (So thought why not) no major shorts, bad connections or damage found as of yet. I’ve cleaned up all the plugs and bullet connectors which were all tarnished and green.

The last bit to do is to look in the headlight and continue to tidy up the loom. I have refreshed the tape with a fabric one I had which looks much tidier.

Yes the bike is a mix of k3 and f parts but it’s how it came and I quite like the look.

I’ll update once I get back on it if anything major is found!
 


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[Bryanj]

The one gone in middle was high current, the one that looks good but isnt is vibration or the contact it clips into loose, so they went for different reasons and it could just be coincidence

[Oddjob]

Another odd thing. Chain guard is plastic on a k but chrome on an f.

Can I suggest filling the bottom 3 slots in the fuse box with spare fuses, they’ll come in handy if one blows. Say a 15 a 7 and a 5? Or maybe 2 orange and a blue as fitted. Always a good idea to carry spare fuses somewhere.

[Towsejames]

Another odd thing. Chain guard is plastic on a k but chrome on an f.

Can I suggest filling the bottom 3 slots in the fuse box with spare fuses, they’ll come in handy if one blows. Say a 15 a 7 and a 5? Or maybe 2 orange and a blue as fitted. Always a good idea to carry spare fuses somewhere.

Ah yes. That is my plan, I will carry 2 spare 15 and a spare 7 for the lights.


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[Towsejames]

So many minutes of cleaning and tightening connectors and things are looking much tidier. Nothing crazy found except a few questions marks.

First one being the horn. My horn is fed with a pale green wire and another wire earthed to the frame of the bike. There is a black wire that runs with the pale green which was left off. The horn works as it is. The black wire has 12v when the ignition is on. Would anyone have any pics of how their horn is wired for reference.

Also a green terminal connector is left floating behind my flasher relay - I’m not sure if this is spare or meant to be connected somewhere. (Everything seems to work fine).

Finally look at how my pilot lamp is held in! And has been for the past I’d say 20 years or so. Can anyone let me know how this is meant to be. And also does this whole unit need replacing if the headlight bulb blows? Since I can’t see a way of removing a bulb.

Finally at the headlight plug I’m only getting around 8v for dip and high beam is this correct or should this have 12v

Thanks in advance.


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[Towsejames]

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[K2-K6]

"Finally look at how my pilot lamp is held in! And has been for the past I’d say 20 years or so. Can anyone let me know how this is meant to be. And also does this whole unit need replacing if the headlight bulb blows? Since I can’t see a way of removing a bulb."

Correct in replacing the unit.

These are "sealed" beam headlight unit made as one construction. It's effectively a giant bulb with a front panel incorporating the lens. This, unlike more current units, with separate individual bulb mounted into a reflector and lens arrangement.

Voltage at lamp should be same as the battery float level (12v upwards) and possibly shows with that 8v that it could have resistance on the line between battery and terminal.

[McCabe-Thiele (Ted)]

Was the 8 volt reading taken with the headlamp illuminated or is it voltage at the feed wire when disconnected from the bulb?

The earthing of the Headlamp bowl/casing would be my first check.
On my 500 I made an earthing cable up similar to the 400 arrangement to ensure a good grounding, my lamp was not a sealed beam unit, I also fitted an earth strap to the front frame iirc. I fitted a complete Osram LED unit for a Land Rover, not my idea, from a member here (Allan) Not for the purists, good for night riding, Halo side light unit, indicators built in to the unit but not used. Less power consumption than a standard headlamp bulb with around 3 times the light output.

#52670411081_9c2f8607e9_b by Macabe Thiele, on Flickr

[Bryanj]

That is a US sealed beam unit as used on cars and the pilot bulb is not required there so there is no proper fitting, you can fit any 7 inch light and go Halogen(usually H4 bulb) BUT , no matter what Delta says, you need to keep the revs up to charge the battery, you could also fit a standard 500 or 750 unit but not 400

[McCabe-Thiele (Ted)]

Continuing on from what Bryan says.

I am not 100% certain, the rim kit for your bike should enable you to fit almost any 7" headlamp unit of choice.
A modern Halogen H4 type bulb will be a vast improvement in light output but would use a tad more watts, you can fit an LED bulb or go completely LED saving watts with more light output.

[Bryanj]

Ted a standard 7 inch will fit in those rims, i have done it when you used to be able to rumage in breakers yards, one thing you do have to think of is that car lights dip down and left with a distinct cut off whilst motorcycle ones tend to dip straight down with no cut off

[florence]

I have a Land Rover Series headlamp in mine with a H4 bulb fitted.  Works fine.  I do not use a pilot bulb, it is not a legal requirement and I cannot see the need for it unless parking on a dark road which I never do.