Topic: 1970 CB750

[Johnie]

Looks as though a fusebox is in order then! Makes me wonder what the F-I-L did with all the parts to this bike!

Yah, you would think he would keep the fuse box somewhere...

[jbonham]

I should be making an order from Service Honda this weekend or Monday. I need the handle bar bridges that secure the bars to the top bridge, any accompanying screws and washers, top bridge washers for tightening to the triple tree and a right side control for headlight and starter button.

I will need some other parts as well but am starting with those for now.
 

[jbonham]

Alright, I made a lengthy list of things I am ordering from Service Honda today. Its about $130 in parts alone not including shipping. Mostly it's screws and washers and nuts for various parts on the bike. One thing still eludes me though and that is the "D" shaped washers for the top bridge. Service Honda has them as discontinued but when I call I am going to ask specifically for that part. Also, I didnt see listed on their site the bearings for the top of the triple tree. Any idea where I can get those?

Here is a list so far.

1. Handle Bar Holders
2. Front Fork Bolt (screws on top of triple tree to secure it to the neck) Is this right?
3. Fuse Box Assmebly
4. Speedo Bracket
5. Tach Bracket
6. Throttle Pipe
7. Left Side Grip
8. Right Side Grip
9. Misc. screws, nuts and washers
10. Oil Filter (Could I get this cheaper somewhere else?)\

Let me know what you think!

[Hinomaru]

One thing still eludes me though and that is the "D" shaped washers for the top bridge. Service Honda has them as discontinued but when I call I am going to ask specifically for that part.

You can always make your own upper bridge clamp washers. See this thread posted by MCRider on how it's done:

http://forums.sohc4.net/index.php?topic=72765.0

[jbonham]

Awesome. I had thought about doing that but wasnt sure about the thickness and diameter of the washers.

Thanks for the tip on the thread.

On another note, I received in the mail today a carb return spring and hardware from member amerdunbar. I ordered it Friday morning and received it Monday before noon with my mail. Thumbs up to Dunbar for quick order fulfillment and shipment. Left PA on Friday and in Dallas, Texas on Monday. That is what I call fast!

Thanks Amerdunbar!

[jbonham]

Wondering if there is someone out there that has an original or aftermarket fusebox for my K1? I posted in the parts wanted section of the forum but no reply as of yet.

[Kevin D]

bearings for the top of the triple tree

Many replace the loose bearings with an aftermarket tapered roller bearing kit, includes bearings for top and bottom of triple tree. $40-50.
Check your old lower races carefully. I had one cracked and another one dimpled.

original or aftermarket fusebox for my K1

A new original will be about $25. An old original with old/loose/corroded connections might be troublesome. For an alternative you might try a 15A automotive blade type fuse. I dunno if I have seen an aftermarket kit using the blade type fuse.

[754]

Balls should be 1/4 inch....250 dia.
 Bearing supply house should have them, and cheap.. check your race and cone condition, & use grease.

[jbonham]

I will post some pics of what is on the bike. The F-I-L put a 15amp fuse on the bike but I wasn't sure what it was for. If that is all I need then an original fuse box wouldnt be needed right?

Thanks!

[Kevin D]

The F-I-L put a 15amp fuse on the bike but I wasn't sure what it was for. If that is all I need then an original fuse box wouldnt be needed right?

Yes, one 15A fuse in the red wire for the entire bike.

[jbonham]

I have the 15amp fuse. Red on one side and white coming out the other. Does this connect to red on both sides and he added the white wire as an extension?

So I wanted to edit this post so that you can see what I am working with here. I think I have the fuse situation figured out but need a little help with one connection on it. The battery cable has a broken wire (red) in the pic that I am going to say connects tot he other side of the fuse (white wire extension)? If the pics aren't clear just let me know and I will try to get some better ones.

[Kevin D]

OK Judd, thats a circuit breaker and probably there because your F-I-L got tired of blown fuses. It doesnt necessarily trip the instant the current exceeds 15A like a fast acting fuse would but if there is/was no melted wire anywhere it might be OK. Can you ask him about it?

Was the white wire spliced to the red one that I marked?
Did the other red one on the circuit breaker go directly into the main harness?
 
Here's a nice interactive wiring diagram:
http://oldmanhonda.com/MC/wiring750K1.html

[jbonham]

Yes, the other end of the fuse goes straight into the main harness. The fuse has two legs of course. The red one from the main harness and then the other leg has a white wire attached to it in one of the pictures above. Its the one where I am holding a white wire and you see the fuse in the background upside down. I am thinking though that he did that white wire on his own as a fix for some reason and that it connects to the small red wire that comes out of the battery cable. If all that is true then I will be replacing the connectors on it so that it stays in place and isn't just twisted together and wound with electrical tape.

Edit*

No melted wire that I have come across as yet in this whole rats nest. So if this is a circuit breaker then I will still need a fuse assembly of some kind right?

[Kevin D]

No melted wire that I have come across as yet in this whole rats nest.

The trick here is to keep any from occurring. And I sure dont want to help you make any.

So if this is a circuit breaker then I will still need a fuse assembly of some kind right?

Not necessarily. Fuses and circuit breakers do the same job. but your circuit breaker is an unknown, non-stock item. Honda engineers chose the glass tube fuses (cost?). Your F-I-L chose a circuit breaker (convenience?). When either one opens its important to know why it opened, correct the problem, and not just press the reset button and try to go on your way.
 If your breaker is the equivalent of the fuse and you wire it back in correctly, no problem.
 If you miswire the breaker back into the circuit, big problem.

[HondaMan]

The old clips on the old style fuseholders got corroded and lost their spring temper from years of mild heating while in use. This slowly caused an increasing frequency of heated glass fuse ends, which damages the sloder in those fuses: then they blow for no reason because the collection of poor connections (2 loose clips + 2 crystallized solder joints on the element + loose element = overheated element, blown fuse). This is extremely common and pushed the designers (over the years) to switch to other types of fuses to prevent it on modern vehicles (not just bikes!).

When I rebuild these bikes, I change to blade-type automotive fuseholders. The fuses are far more reliable and much more widely available. 

[jbonham]

I am taking a guess that the other end of the circuit breaker (white wire) will go into the red wire attached to the battery cable but I am going to ask the f-i-l anyway. I feel pretty certain that if the oem fuse-box connected that way then he just removed it and inserted circuit breaker *here*. Of course it is a guess but it makes sense. I will find out shortly. There are lots of other wires that I have taken pictures of and will need help with. Hondaman's interactive wiring diagram helps a lot in conjunction with what is in the original shop manual (yes it's 40 years old) and the new Clymer manual. I have heard some disparaging things about the Clymer diagrams but haven't run across anything that steers me in the wrong direction yet. Any truth to this?

On another note, I have a bunch of parts coming Wednesday that should get me almost buttoned up on the handlebars. The excitement is building! I may even have it started by the end of the week but we will see.

Ideas on a good break in oil for starters?

Thanks.

[Kevin D]

When I rebuild these bikes, I change to blade-type automotive fuseholders. The fuses are far more reliable and much more widely available.  

Heres a fuseholder similar to what Hondaman is referring to. $3 at Lowes. Found it at OReillys Auto too.

http://www.lowes.com/pd_321955-73694-BP/HHG-RP_0_?newSearch=true&catalogId=10051&productId=3138837&Ntt=atv+cover&N=0&langId=-1&Ns=&storeId=10151&Ntk=i_products&ddkey=http:CategoryDisplay

[jbonham]

I hate waiting for the UPS man!!!!!!!!!!! I keep looking out the window in anticipation of that package. UPS site says "out for delivery"!!!!!!

[jbonham]

I received parts from Service Honda and got all of what I needed to get the handlebars on. Funny how the bars seem to make a big difference in appearance. Somehow it looks cooler with bars now even though the rest seems pretty ratty. Routed throttle cables today and and adjusted the clutch after getting the left side controls on. Had to rebuild the start button by soldering the wire back on and then replacing the spring with the help of some donor writing pens around the house. Cheap writing pens have surprisingly good springs for things like start and horn buttons.

[jbonham]

I got close to getting the bike started late today. The rain held off so I was out in the leaky workshop early.

I never got the bike started but it turns over now. I guess it's good that nothing popped or caught on fire when I hit the start button. I fear I may be dealing with a fuel cock that isn't delivering fuel properly. I had the hoses connected but when I took them off I saw that no fuel came out of the lines themselves. I did a flow test that is outlined in the original shop manual which is simple. Disconnect the hose from the tank and then pop one of the outside bowls on the carb. Try to start. If you get fuel coming through the carb then you know you have flow through the lines. I guess the test is assuming the fuel would be in the lines already after being removed from the tank. Not sure on that though. Does this sound right?

So what's next? Pull the fuel cock and try to clean it? I tried earlier but the two screws inside the assembly wouldn't budge so I feel as though the rust has seized them. I am going to patiently deal with this issue along with researching the boards here for answers but for now that is the problem I am having.

[jbonham]

After getting everything essential back together on the bike I decided to hook up the battery and give it a go.

First, it doesn't start, at all, plain and simple. It turns over like it wants to but nothing. Fuel in tank and the hose gets fuel running down it to the carb.

Second, after getting everything wired back together, anytime I hit the headlight switch I blow the fuse. Unhook the headlight wires and everything is fine, except that it still doesn't start, but no blown fuses.

I have posted some pics below of it back together. Obviously missing a few things but nothing that will keep it from starting. It aint pretty but I think If I get it started it will look better.