Topic: Andys CB810 K2 -updated 14 Oct 2024 - missing link!

[andy750]

Last night on a test ride on the K2 I was accelerating on a twisty road when...bike died...no power....I managed to cruise for another 300 meters and pull over on a side road. Tried another 15amp fuse and when turned on ignition it blew straight away. Checked the wiring as best as I could...positive terminal on battery was a bit loose so tightened that up and tried another fuse...blew immediately.

Fortunately I always carry spares for times such as this. 3 left....ok let me think I had an intermittent headlight the other week and found the white wire when kinked would cause headlight to go on/off...thought I had fixed that but lets see...turned off headlight and replaced the fuse. Bike started no problem and I managed to ride home. But what happened?

About to go troubleshoot...suspect headlight wiring shortening on something blowing main fuse...any other ideas?

thanks
Andy

[Jerry Rxman Griffin aka MuthaF'er]

Andy, does your K have a separate fuse for the headlight like my F does? If so unplug it and see what happens with the 15A??? Or if not remove the headlight bulb. Headlight on/off in the switch or always on? I had a bad/broken headlight plug once??

[Alan F.]

My first thought was that it may not be a short but a dirty switch contact causing a higher than normal current condition. Measure for resistance across the headlight switch in the ON position.

On models that have the start button interrupting the headlight circuit, I'd measure for resistance there too.

Also disconnect handlebar switches from harness to inspect for dirty pins.

[PeWe]

My K6 had an aftermarket brake switch for rear brake. The insulation over the bullet plugg moved off the connection that became not insulated. The connection touched frame engine mount.

Main fuse 15A blew when I used brake pedal which I did automatically without thinking. I had to think what happened.

That circuit should have its own fuse instead of killing bike when shorted.

I repaired the insulation and strapped it together with points cable not touching ground.

[andy750]

Thanks for all the great suggestions. Jerry its a one-fuse K2 - the 15A does it all.

I opened up the headlight and noticed that the headlight would go off/on by moving the white wire to the headlight. So I stripped the switch side and put on a new bullet connector and also noticed the 3-prong assembly had some loose connectors so adjusted those. I checked the hi/lo wires and switch and after these mods all looked good. Didnt have the chance to test drive today but maybe its as simple as wiring? Bike now turns on and headlight works. I have ordered an Eastern Beaver headlight relay (have it on my K and like it) as well as a new battery (old one is very old). Current battery was flashing 11.4 volts (inline volt meter) when headlight was turned on - drop from 12.2.

Will test drive Sunday evening and see if current mods have helped.

Thanks again
Andy

[Alan F.]

Sounds like a win Andy.

[scottly]

The white wire is for the low beam, so if it was shorted to ground, it would blow the fuse when the switch was set to low, but not when set to high. Have you tried both switch positions?

[PeWe]

I'm a little bit worried about my K2 with only 1 fuse. Install relays will relieve the current thru the switches and harness. Also provide thicker wires from battery. Hanging fuse for the 12V feed to relay. 

My K6 with relays and thicker wiring to the biggest loads thru relays seems to have made the charging voltage more stable too. Compared to my K2 with all new wiring, NOS ign switch.

The 7A or 5A fuses blew only a few times on my K6,  mostly 15A fuse.

I had problems due to the grinded openings for outside harness routing were too shallow, squeezing the wires between switch housing and handlebar. Short circuit could happen.
I repaired the fuse by a strand from a wire winded outside the fuse that kept it in place.

[andy750]

The white wire is for the low beam, so if it was shorted to ground, it would blow the fuse when the switch was set to low, but not when set to high. Have you tried both switch positions?

I did check for that and it seemed to be localised to the white wire (low beam). For now with new connectors on the white wire (from switch) and from headlight shell end this seems to have done the trick -no blowing fuses when switch on. I did notice the 3-prong connector at the bulb end is a bit loose so may replace that as I already have the Eastern Beaver headlight relay coming: I used the relay in the K4 at start of year. Its a bit tight but it does fit.

Ill keep this thread updated if this fix dosent hold.

thanks again for all the input.
Andy

[andy750]

So...that didnt work....test ride tonight and I got maybe 300 m before the fuse blew. I replaced it, turned the headlight off and rode home. Back to troubleshooting. 

[Jerry Rxman Griffin aka MuthaF'er]

What is the output/draw of your headlight bulb? ie Is it stock or high output?

[Kevin D]

Intermittent faults are the worst.....
When you turn the headlight on, of course you're also powering the gauge lamps and the taillight.
The Wiring diagram is for a K1, similar to K2 but I think not identical.
Sorry for the poor screenshot, it's from old man Honda interactive wiring diagram.

[scottly]

So...that didnt work....test ride tonight and I got maybe 300 m before the fuse blew. I replaced it, turned the headlight off and rode home. Back to troubleshooting. 

Was the switch set to high beam or low beam? If the fuse blows only on low, the white wire is rubbing against a ground somewhere between the switch and the headlight. It could be the soldered connection on the underside of the switch hitting the handle bar, or the wire where it passes through the bar if the wires are internal. Fuses don't blow suddenly from a bad connection at the load, they blow when the wires that feed the load are shorted to ground. (The other cause is homotrons.. )

[knowsnothing]

Andy, see if you can get it short in the drive way by doing stuff (turning, bouncing, flipping switches, brakes).  Might give you a lead to chase. 

[andy750]

So...that didnt work....test ride tonight and I got maybe 300 m before the fuse blew. I replaced it, turned the headlight off and rode home. Back to troubleshooting. 

Was the switch set to high beam or low beam? If the fuse blows only on low, the white wire is rubbing against a ground somewhere between the switch and the headlight. It could be the soldered connection on the underside of the switch hitting the handle bar, or the wire where it passes through the bar if the wires are internal. Fuses don't blow suddenly from a bad connection at the load, they blow when the wires that feed the load are shorted to ground. (The other cause is homotrons.. )

Thank you Scottly for the clear explanation which makes a lot of sense to me
. I’ll try this tomorrow night as it’s only been set on low beam so far.
Thanks
Andy

[andy750]

Andy, see if you can get it short in the drive way by doing stuff (turning, bouncing, flipping switches, brakes).  Might give you a lead to chase.

Thanks Treeve I was trying this but on the last test ride it did start up ok and run down the hill. I’ll try more of your suggestions tomorrow night. Hope all is well with you!

[Kevin D]

(The other cause is homotrons.. )

Uhhhh..... can’t find that setting on my meter

[scottly]

A homotron is a promiscuous gay electron that goes around blowing fuses at random.

[andy750]

Update as of tonight:
I noticed the headlight socket wiring was loose and the connecting blades were loose _ touch it and bulb goes off. I replaced it and installed an Eastern Beaver headlight relay (so now with dedicated headlight fuse) - test drive tonight confirms problem solved!

Thanks to everyone who gave me some great ideas to test (which I did).

Of course a new problem arose tonight - #2 not firing optimally on start up and very low idle once warm - dies at traffic lights and hard to restart. So one problem solved and another to figure out 

Cheers
Andy

[PeWe]

Typical!
Maybe only dirt in carb 2 pilot circuit?
Remove float bowl, pilot jet, air screw and spray some cleaner. A little compressed air by a light hand.
The 2 air vents tubes must have free flow too when blow into them lightly. I do not know what these vents can cause, good idea to verify them now and then.

Same with all 4 over flow tubes and the brass tube in each bowl.
It seem they are involved in how the carbs can breathe.

I had strange over or under pressure behavior when parked on side stand with hot engine.
Fuel ran to #1 and overflowed into airbox. It had small holes (~2mm) in each corner I drilled before as fuel overflow drain.

The overflow brass pipe was not completely blocked, almost. Improved with steel wire. Did all 4.
I was not sure if it was overpressure affecting the other, or under pressure in badly vented #1 that sucked fuel into it.

[andy750]

.... by a light hand.

I am not usually so heavy handed but in my haste to find the problem I popped off #2 bowl and with no stubby screwdriver at hand I used a small ratchet with a flat head attachment to remove the pilot jet....lefty-loosy...only somehow I snapped the pilot jet and now the threaded end is stuck in the carb  Talk about creating a new bigger problem while trying to solve a small problem 

[PeWe]

I have broken pilot jets in my carbs too. 2 carbs. 4-1 aftermarket pilot jets were too tight, snapped when tighten 2 of them.
I thought it was a tight thread that new jets usually have, but it snapped  after the thread. Too thick jets.

Took off the carbs, drilled the holes very easy, 2.0mm drill in all 4 to get exactly same dimensions on all. It might shaved very little of the alu.
Measured the depths in the other carbs without pilots. Drilled a little, checked, drilled again to not drill too far.

http://forums.sohc4.net/index.php/topic,168243.msg2071582.html#msg2071582

Your pilot sit with the thread left in carb.
If you are lucky heating up the carb and a sharp screwdriver might get it out.

[andy750]

As always Per thank you for the reassuring words and for letting me know I am not the only one who has broken off the pilot jet in the carb body. Very much appreciated.

I have had this bike for 20 years you would think i would know better! Fortunately I have a spare set of clean carbs to put on while I deal with the broken pilot jet - friend of mine has small extractors if I am unable to get it out myself and failing all of that I will try your drill method - though if MikeR is up to having visitors I may have to go visit him as he is the master of removing broken things - watched him remove a heavy duty stud from the K2 engine before was impressive.

Will keep you all posted on progress.

cheers
Andy

[seanbarney41]

I have done it before too, although it was crudded up carbs....its probably best to just twist out main jet and emulsion tube as one piece, then separate in convenient open space.

[PeWe]

Hi Andy,
Good ensurance to have a spare set.  It is difficult to find a complete carb set for K1-K6 for OK price.

The brass has been sitting long into the soft aluminium, right?
It seems they can form together, a little corrosion can make it sit harder I guess.

But this kind of things are normal when wrenching. 1 step forward 3 steps backwards.
It is very common for me that something must be repaired or taken apart again when doing something simple.

My last jobs on my bikes have been success though, I could have done it like a pro for a paying customer. Clutch and front tube replacements.
Mostly  double or triple time its worth to pay for.

It will be a happy ending if not giving up