Author Topic: Sorting out PO's "tweaks" on 750 K7. Yet another project.  (Read 2146 times)

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Offline b1jackson

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Sorting out PO's "tweaks" on 750 K7. Yet another project.
« on: August 19, 2017, 11:30:20 am »
Hello all,
I've wheeled this 750 project onto the table now.  While waiting for a carb kit for a rebuild, I decided to start to give this old girl a look over to see what I might be in for.  Of course, the typical barn find though a few pieces here and there missing.  The first PO "tweak" I need to sort out is ignition.  I'm not sure why (is there always a reason?) but the original ignition was cut out.  I have a red, a black, a brown, and a brown/white wire.  An ignition with key was thrown in on the deal so no idea what CB model it is from.



For now, I'm just going to temporarily make some connections to see if the bike will run.  I'll make a permanent solution later on and perhaps splice in a proper harness section.  To save a lot of sparks and blown fuses, which wires go to which ignition switch terminals?





Frame crack.  The next issue. Almost appears slightly split outward like a pipe burst.  Right infront of the gear selector.  Probably not a deal breaker but I would assume a good weld job would do the trick.  Someone who can weld light and old metal.  If I decide the bike is a keeper, I may just hunt down a better frame.



Exhaust modification.  I don't know if the bike over operated like this but there is an F header on the bike and for what was likely clearance issues, the brake pedal was removed.  The brake pedal wasn't included but doesn't that look awfully snug to fit a pedal in?  Does anyone run an F pipe on a K7 and not have issues with a functioning pedal?






Offline b1jackson

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #1 on: August 19, 2017, 11:44:38 am »




For now, I'm just going to temporarily make some connections to see if the bike will run.  I'll make a permanent solution later on and perhaps splice in a proper harness section.  To save a lot of sparks and blown fuses, which wires go to which ignition switch terminals?


Standby.....dang pic won't load on the hosting site,  I have a pic of the back of the switch with the terminals numbered.

« Last Edit: August 19, 2017, 12:03:18 pm by b1jackson »

Offline CycleRanger

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #2 on: August 19, 2017, 12:21:33 pm »
Jump over here and grab the shop manual. It will have the wiring diagram.
http://www.honda4fun.com/materiale-documentazione-tecnica/shop-manual

That split in the frame is usually caused by water getting in the frame and freezing.
(That screw head looks pretty awesome too..) ::)
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Offline b1jackson

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #3 on: August 19, 2017, 12:26:44 pm »
Yes, it does look like a pipe split.

Offline b1jackson

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #4 on: August 19, 2017, 12:39:21 pm »
Looking closer you can see the engine was rebuilt or at least removed and taken apart. Tell tale signs:

- Minor remnants of silicon goop at base gasket and head gasket. 

- couple of the motor mount bolts (long one) replaced with a long piece of threaded rod.?

- some stripped and mangled screws.

Offline b1jackson

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #5 on: August 19, 2017, 04:09:49 pm »
Switch now temporarily wired.  Few squirts of oil down the cylinders. Spins right over. Got spark too!  Carb boots getting a minty soak.  Chrome getting polished up.

Waiting for parts is the worst!

Offline BPellerine

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #6 on: August 19, 2017, 05:39:27 pm »
barry,I saw the group of bikes that one came from,some of them were bitsas,and some one liked silicone alot,you may have a mixture of parts.bill
1978 CB 750K ard and webers
another anfob

Offline b1jackson

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #7 on: August 19, 2017, 06:02:20 pm »
Yes.  The muffler on this one is a Kawasaki apparently and the header is definitely an F model.  Engine looks nice and clean though so hopeful is was a recent rebuild that had very little running.  Things are not all caked with oil and grease anyway.

Can't wait to hear what it sounds like.

Offline calj737

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #8 on: August 20, 2017, 04:45:42 am »
This may sound a bit odd but, I would drill a couple of small holes near the top of the down tubes, then using a small funnel, pour a generous amount of MetalRescue/Rust Converter into the tubes. This will help treat any internal rust, show you any more holes, plus help identify whether the drain plugs are indeed clogged.

You can use some Duct Tape to temporarily seal that split so the fluid doesn't leak out.

This treatment is important before any welding repair is performed as MIG or TIG won't weld properly with rust on the inside of the tube. Once treated, that split can be washed over with new filler, then carefully ground/sanded down to original shape. Or a small patch section over top after repairing the split.

I'd perform this task on the subframe section too for the passenger brackets. After you've treated the internals, just spot weld the holes closed.
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Offline b1jackson

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #9 on: August 20, 2017, 07:08:54 am »
Good advice.  Where abouts are the drain plugs? 

Offline calj737

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #10 on: August 20, 2017, 10:59:06 am »
Should be some just in front of the passenger triangles at the bottom.
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline 754

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #11 on: August 20, 2017, 12:29:59 pm »
Typical frame damage from water freezing in there,  as it is no water can collect in there.
I suspect going mad at the carwash, May be part of the cause.
 I ain't washing mines just to stay safe.
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Offline b1jackson

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #12 on: August 25, 2017, 09:02:11 am »
Does anybody have any thoughts on that rear brake lever and the seemingly tight clearance with the use of the F header?

Offline BPellerine

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #13 on: August 25, 2017, 01:34:56 pm »
the f bikes have some frame differences,and maybe a diff brake pedal,looks to me like the f header will not work.bill
1978 CB 750K ard and webers
another anfob

Offline b1jackson

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #14 on: August 26, 2017, 07:34:39 am »
Yep.  I swapped on a F pedal and the spline hole is larger and no way the pedal will work.  I'll likely just stick on an aftermarket and keep the F header.  It's in nice shape.  Hopeful to have it running today once the battery charges up.

Offline BPellerine

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Re: Sorting out PO's "tweaks" on 750 K7. Yet another project.
« Reply #15 on: August 26, 2017, 10:07:18 am »
yeah,the 78ks have a smaller spline,maybe a 78f is the same?bill
1978 CB 750K ard and webers
another anfob