Topic: 1972 CB750 Four K2 -- Rebuilt to NEW OLD STOCK -- PIX ON PAGE 50

[edwardmorris]

Well, I opened up the rat's nest again, everything is connected as it should be, but I'm having serious doubts about the above diagram. To test things out, I disconnected the buzzer and it made no difference, front ones turn on but not blink, rears don't turn on at all. The rears, I'm using the Z1 enterprises repop grounding brackets so its possible there's a bad ground there, will have to look closely. I switched the connections at the flasher relay and that made no difference either so at this point it seems likely that the NOS flasher is a dud. I'll have to dig out my old one and swap them out to see if that makes a difference (after figuring out what's wrong with the rears of course).

The gauge lights issue is fixed, turns out one of the terminals got disconnected when I pushed the headlight into place. Reconnected, now they come on as expected with the headlight.

[calj737]

Before you jump the gun on your flasher relay, it is dependent upon voltage to function properly. If you're still down near 12.0v, it may need you to fire the bike and generate sufficient volts to heat the relay up before it commences sending our morse signals to our allies... (Maybe)

Get your battery fully charged and re-test.

[Ravie]

I'm glad to see I'm not the only one of the two of us at the same point and having nearly the exact same issues...

Mine...headlight won't come on, front left turn signal is lit all the time. Horn works. Stoplight works, though I get no tail light from it.

How can wires that are the same color be connected and still not function properly?  lol

[edwardmorris]

Well, could hardly sleep and came up with 16 different ways I could rewire #$%* to make it all work. Then, woke up this morning and had a sound recollection of what an administrative assistant back in college once told me "Keep it simple, stupid" or KISS. I had a suspicion that the repop brackets on the rear winkers weren't grounded right as they have paint all over everything, including the threads of the mounting screw. I took a key and shorted them out and boom, flasher relay kicked in, buzzer started coraking, and both the front and rear winkers are now flashing.

So the gauge illumination is solved, winkers and buzzer is solved, there's only the matter of the tail light. First I need to know what the default behavior for the tail light is. I'm assuming it should come right on once the key is turned away from the off position. If so, then I'll need to split the signal from the black wire in the headlight that is currently feeding the buzzer and also feed it to the one stray brown wire in the headlight bucket. If it is supposed to come on when the headlight is turned on, then I'll need to split the brown/white wire and feed it to the one stray brown wire in the headlight bucket.

[evanphi]

Well, could hardly sleep and came up with 16 different ways I could rewire #$%* to make it all work. Then, woke up this morning and had a sound recollection of what an administrative assistant back in college once told me "Keep it simple, stupid" or KISS. I had a suspicion that the repop brackets on the rear winkers weren't grounded right as they have paint all over everything, including the threads of the mounting screw. I took a key and shorted them out and boom, flasher relay kicked in, buzzer started coraking, and both the front and rear winkers are now flashing.

So the gauge illumination is solved, winkers and buzzer is solved, there's only the matter of the tail light. First I need to know what the default behavior for the tail light is. I'm assuming it should come right on once the key is turned away from the off position. If so, then I'll need to split the signal from the black wire in the headlight that is currently feeding the buzzer and also feed it to the one stray brown wire in the headlight bucket. If it is supposed to come on when the headlight is turned on, then I'll need to split the brown/white wire and feed it to the one stray brown wire in the headlight bucket.

The brake light (running light, dimmest of two filaments) should come on with the headlight. Turn the headlight off, brake(running) light is off, too. If the headlight is off, the brake switches will engage the brighter filament only.

[edwardmorris]

Well, could hardly sleep and came up with 16 different ways I could rewire #$%* to make it all work. Then, woke up this morning and had a sound recollection of what an administrative assistant back in college once told me "Keep it simple, stupid" or KISS. I had a suspicion that the repop brackets on the rear winkers weren't grounded right as they have paint all over everything, including the threads of the mounting screw. I took a key and shorted them out and boom, flasher relay kicked in, buzzer started coraking, and both the front and rear winkers are now flashing.

So the gauge illumination is solved, winkers and buzzer is solved, there's only the matter of the tail light. First I need to know what the default behavior for the tail light is. I'm assuming it should come right on once the key is turned away from the off position. If so, then I'll need to split the signal from the black wire in the headlight that is currently feeding the buzzer and also feed it to the one stray brown wire in the headlight bucket. If it is supposed to come on when the headlight is turned on, then I'll need to split the brown/white wire and feed it to the one stray brown wire in the headlight bucket.

The brake light (running light, dimmest of two filaments) should come on with the headlight. Turn the headlight off, brake(running) light is off, too. If the headlight is off, the brake switches will engage the brighter filament only.

So I'll need to split the brown/white wire for that to work. There's no such path in the wiring diagram though. The only thing going to the tail light besides the brake activation green/yellows is the brown wire, which is only powered via the key switch. How did the factory wire this, K2 owners?

[HondaMan]

On the K2, the headlite should only come on when the OFF-LO-HI switch is on. And, the taillight comes on with it. The taillight gets its power via the Brn/Wht-thru-the-keyswitch-to-the Brown (to the taillight) when the key is in RUN  position. Does your headlight (OFF-LO-HI) have the 4 wires from it? They should be: Blk, Blu, Wht, Brn/Wht (or might be Brn/Yel sometimes, same thing). Then the Brn/Wht should go directly to a Brn/Wht in the headlight, which goes to the keyswitch.

[edwardmorris]

On the K2, the headlite should only come on when the OFF-LO-HI switch is on. And, the taillight comes on with it. The taillight gets its power via the Brn/Wht-thru-the-keyswitch-to-the Brown (to the taillight) when the key is in RUN  position. Does your headlight (OFF-LO-HI) have the 4 wires from it? They should be: Blk, Blu, Wht, Brn/Wht (or might be Brn/Yel sometimes, same thing). Then the Brn/Wht should go directly to a Brn/Wht in the headlight, which goes to the keyswitch.

THAT makes sense, and I may have gotten a little too excited with the color matching. When you ask "Does your headlight (OFF-LO-HI)..." I'm assuming you're talking about the right hand switch? If so, then yes, it does have them all coming out of it, only I took the brown/white and hooked it up to the main harness  brown/white triple female, along side the gauge lamps, which I'm now thinking is where the issue is.

If you're actually asking about the headlight, then no, there's only the three wires going to/coming form it, and no brown/white.

[HondaMan]

Yep, the headlight has the 3, Grn/Bu/Wht. It's the handlebar switch where the others are. Did you actually get a handlebar switch with the 3-female connector attached to the Brn/Wht? I haven't seen one of those in many years. They were replaced with one that had a detached 3-way with a little pigtail on it so the wires could be more easily pulled thru the handlebars, I suppose? Then the 3-way was plugged in, in the headlight bucket.

[edwardmorris]

Well, I was right about the rear winkers, z1 or 4into1, whoever made it basically painted the crap out of the rear mounting bracket first, then riveted the connector in place. Very hit or miss with that riveting mechanism on a painted part to actually make any electrical contact. Took em off, and dipped a thread chaser in paint stripper and sent through. Scraped off some more paint on the opposite side where the stem's insert goes for additional contact. Quick test with the beeping meter and all is good. Dielectric grease and installed back in place, all is good with the winkers, although the buzzer sounds like a dying bird  thank goodness for that cancel button

As good as I felt about calling that one and fixing it, the whole taillight mess made me feel like a total idiot. I was about to rig up splitters and such using chunks off the old harness to power the taillight then, that voice in my head came back, "Keep it simple, stupid"! After reading Mark's explanation above, the key here is that the tail light will turn on along with the headlight through the key switch. So there is no brown/white wire going to the taillight yet the brown/white wire is sending it power by feeding the brown wire through the switch.

That said, I went through the rat's nest yet again, everything is exactly where it needs to be. So why isn't the taillight coming on? Its because the moron working on this #$%* didn't actually go BEHIND THE BIKE to get a good look   The damned thing has been working all along, I just didn't see it

That concludes the electrical gremlins chapter. In reality, there was only one, the winkers.

Final go through of the major stuff, the header clamps. I've tightened them down quite a bit yet they keep slipping out of place. I'm assuming the 8mm bolts are stronger and will take a lot more torque than the standard 15ft-lbs? I don't see it the parts fiche but do I need those two piece collars with the 341s?

[edwardmorris]

Few shots of where things are as of now. I bit the bullet and ordered the gas cap pin with overnight shipping (yeaaaouch!), planning to try and start it tomorrow. I'm anticipating some carb/fuel or more electrical/coil related non-sense. I'll have to pull the left cover off and rearrange the components again, don't like that big connector showing like that.

Final check list after it fires up is

   Dynamic timing/Dwell setting
   Install the NOS fork lock (came with the ignition switch) and its new cover from yami.
   Install the NOS points cover with its gasket and new screws.
   Install the new brake bleeder cap (should just do this now).
   Install all the warning stickers throughout.
   Adjust the rear brake some more (pedal goes too far down before it engages).
   Put a few miles on it and vacuum sync the carbs.

[evanphi]

Very excited to hear that startup! Please take video!

[oldhatt45]

Hey Rafi,

It Looks like a New BIke!!!!!!
I'm with evanphi, take video of the Startup!!!!

Charlie

[calj737]

8mm bolts take 15#, no more. Don't be a ham fist, solve the problem with your brain, not your brawn

[edwardmorris]

8mm bolts take 15#, no more. Don't be a ham fist, solve the problem with your brain, not your brawn

That's what I thought. I'll fire it up and look for exhaust leaks closely. If there are any, then I'll have to dig into it. For now, things are buttoned up to spec. I'd like to get a vid, but my cell phone barely takes pix. Before you guys boo me off the forum , I should let you know I have made arrangements for a proper photo shoot and a build summary video, just  a matter of scheduling it.

[Restoration Fan]

8mm bolts take 15#, no more. Don't be a ham fist, solve the problem with your brain, not your brawn

That's what I thought. I'll fire it up and look for exhaust leaks closely. If there are any, then I'll have to dig into it. For now, things are buttoned up to spec. I'd like to get a vid, but my cell phone barely takes pix. Before you guys boo me off the forum , I should let you know I have made arrangements for a proper photo shoot and a build summary video, just  a matter of scheduling it.

Booooo!  Boooooo!  That's not as good as a "first fire up" video.  Booooooo! 

[seanbarney41]

Personally, I get really annoyed by first start up videos...crank crank crank kick kick kick, float bowls start puking and nobody knows they just need a good whack, finally starts and runs at 3000 rpm on 2.5 cylinders, omg something is smokin'!  the poor thing probably ran better before the rebuild...

...yeah, this is real cynical, and I am not saying this is you Rafi, just saying there is nothing wrong with start up on your own time, work through any issues that arise, shake it down until it's ready to ride, and then enjoy...it's your bike afterall.

[edwardmorris]

Personally, I get really annoyed by first start up videos...crank crank crank kick kick kick, float bowls start puking and nobody knows they just need a good whack, finally starts and runs at 3000 rpm on 2.5 cylinders, omg something is smokin'!  the poor thing probably ran better before the rebuild...

...yeah, this is real cynical, and I am not saying this is you Rafi, just saying there is nothing wrong with start up on your own time, work through any issues that arise, shake it down until it's ready to ride, and then enjoy...it's your bike afterall.

LOL Almost all of those checked out. Only firing fully on 4 (hot pipe), barely one 1 (warm pipe) and not at all on 2 and 3 (cold pipes). Battery is at 12.6V after leaving it on the tender all day. Thankfully no leak of oil or gas anywhere. For a brief moment it felt like it had come to life but fell flat dead within 2-3 seconds. Soaked in sweat kicking that thing over so many times, used the starter a good few times but don't want to kill off the battery in a hurry just yet.

So lets get started, I'm assuming pulling the plugs is the first order of business?
Can I leave the tender plugged in while the battery is on the bike?

[Restoration Fan]

Can I leave the tender plugged in while the battery is on the bike?

I supposed it might depend upon the type of tender you have, but I have done it multiple times with Stella and it works fine because I usually have it on a slow trickle charge of 2 volts.

[edwardmorris]

Thanks Ron, I'll leave it overnight. Mine's the smart charger, automatically switches to storage mode, but it does do a drip charge.


Spark test shows I've got spark, so I'm dreading a carb issue? Didn't pull the plugs yet, tested with a spare plug, great idea from Bill Benton!

[seanbarney41]

crack open some float bowl drains and see if there is gas in there...using actual fuel tank or some sort of reservoir?

[edwardmorris]

crack open some float bowl drains and see if there is gas in there...using actual fuel tank or some sort of reservoir?

Actual fuel tank. I'd hate to have to remove it as the fuel hoses were a pain to get on right. I'll do the drain test right after I check the plugs on the cold one to see if gas is spewing in there. Tapping the bowls, they seem to all have fuel. Also, #1 is warm, so I'm guessing gas made it through both junctions.

[seanbarney41]

You are probably gonna have to get good at pulling the tank on and off...it's inevitable.  Best quality fuel line makes all the difference...guessing you are fine there and sourced oem Honda 5.5mm

[edwardmorris]

You are probably gonna have to get good at pulling the tank on and off...it's inevitable.  Best quality fuel line makes all the difference...guessing you are fine there and sourced oem Honda 5.5mm

Yep, all new/nos stuff throughout just for that reason. So I think its most likely stuck floats in 2 and 3. It's itching to start, fires really nicely on 1 and 4 at 3000RPM with choke on and throttle pulled ever so slightly, dies off as soon as I let go. Pulled the plug on number 3, its dry as a bone so its getting nothing. I was dumb enough to think that since 1 and 4 are working, fuel is in all 4 (still might be) via the T joints. I know the floats are right next to that. I had made sure they were moving freely when assembled but you never know. I did try tapping them loose, no luck. Too tired right now to think and act clearly, will sleep on it and figure out how best to drain the bowl without gas spilling on my clean engine. I really wanted it running tonight

[seanbarney41]

You are probably gonna have to get good at pulling the tank on and off...it's inevitable.  Best quality fuel line makes all the difference...guessing you are fine there and sourced oem Honda 5.5mm

Yep, all new/nos stuff throughout just for that reason. So I think its most likely stuck floats in 2 and 3. It's itching to start, fires really nicely on 1 and 4 at 3000RPM with choke on and throttle pulled ever so slightly, dies off as soon as I let go. Pulled the plug on number 3, its dry as a bone so its getting nothing. I was dumb enough to think that since 1 and 4 are working, fuel is in all 4 (still might be) via the T joints. I know the floats are right next to that. I had made sure they were moving freely when assembled but you never know. I did try tapping them loose, no luck. Too tired right now to think and act clearly, will sleep on it and figure out how best to drain the bowl without gas spilling on my clean engine. I really wanted it running tonight

cut a little pan from the bottom of a plastic soft drink bottle, crack the float bowl drain open, and let it drain into the mini drip pan...then rejoice in the convenience of the 750's easy access float bowls, just snap the clip and your in there...