Author Topic: 1974 CB750K4 wrench and ride (Read 16161 times)

thrutheframe · « **on:** August 08, 2011, 09:22:04 AM »

I picked up my K4 for $800.00 off of Craigslist. I don't plan to restore this bike right away but will be doing what I need to do to get it running and safe so I can ride it this season.

Here is a list of the obvious things that are wrong with the bike:
No wire harness
Varnish on engine cases
Paint is poorly done with no clear coat and gas has eaten into it on the tank
Side covers are ghetto but painted to match tanks
Head light off, where PO was planning to repair it
Coils off, PO took them off to test them, I'll test them myself
Front fender has some dents
Rear fender has extra holes drilled in it under the license plate bracket
Straight Hooker pipes with no mufflers
Seat has duct tape on it
Timing will need set because PO replaced points and points plate
Good stuff:
Its a CB750K4
Tires are like new
Rims are near perfect
Compression seems good based on resistance at kick start
New Points and points plate
Clean oil
Chrome parts are mostly in nice shape
Cool looking hooker pipes with no mufflers

I'm going to go to my storage unit now and roll the bike out in the sun and take a few pics to post.

thrutheframe · « **Reply #1 on:** August 09, 2011, 04:57:34 AM »

Pappykono · « **Reply #2 on:** August 09, 2011, 08:25:41 AM »

Looks pretty good. Is that a shackled rear end?

thrutheframe · « **Reply #3 on:** August 09, 2011, 11:13:34 AM »

Quote from: Pappykono on August 09, 2011, 08:25:41 AM

Looks pretty good. Is that a shackled rear end?

Yeah, I Iike that lowered look. For now I'm keeping the drop links and the hooker pipes.

thrutheframe · « **Reply #4 on:** August 13, 2011, 02:26:17 PM »

Im waiting on my wire harness from parts n more. I think those guys have quality stuff but everytime I order form them I I forget how slow they are to ship stuff.

thrutheframe · « **Reply #5 on:** August 16, 2011, 06:04:19 PM »

I received my wire harness today. I inspected it and spot checked it against the wiring diagram I have in my service manual. Everything I looked at matches and the crimps all look nice.

Tomorrow night I'll take an hour or two and put it on the bike. I'm working everyday 8 to 5 for the forseeable future so I have less time now to wrench.

thrutheframe · « **Reply #6 on:** August 20, 2011, 06:52:42 PM »

Got a chance to start on my wire harness and take a closer look at my 750. The carb boots on the airbox side are toast. The cylinder head side are fine. I ordered the boots, a gas tank rear rubber strap, a cam gear seal for my tach cable, and a hand full of nuts and bolts. 80 bucks but worth it I'm sure. The carbs are pretty nasty. Im thinking about just pulling them. The PO had a nice new filter in the air box but hadn't adressed the carb boots.

That's carb 2, they all look like that.

thrutheframe · « **Reply #7 on:** August 22, 2011, 03:07:10 PM »

I got the headlight mounted and the harness mostly sorted out. I just have a few wires that I hadn't figured out as of last nights' adventure.
My head light bucket was missing one of the collars/ spacers that the mounting bolt goes through. I couldn't find a replacement in metal but I did find some nylon bushings with a collar. I cleaned up the hole a bit and the nylon bushing went right in. I had to cut the spacer back so it would fit inside the channel molded into the headlight bucket.

Not the best pic but you can see where I cut the ears off square. The stuff is pretty heavy duty, I had get out the dremel to cut it. Hopefully it will hold up for years to come.

I had to hunt down a legible wiring diagram too. The one I downloaded from here was pretty hard to sort out, it being in black and white and the scan being not so great. I found one that looks pretty good.

http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php#class

The resolution is good enough that I can store the image in my iPhone and use it as a reference.

I also used the search function here in the forums and came up with this sweet replacement flasher relay:

I'll be testing it out here in a bit, if it doesn't work I'll pull the pic and my text reference to it from this post.

thrutheframe · « **Reply #8 on:** August 23, 2011, 03:03:00 AM »

Everything checked out pretty good except my right front turn signal is bad. The running light comes on but the signal doesn't fire. That will have to wait until I get back from Columbus.
I have all of my indicator lights, the rear brakelight works (front has no fluid in the MC) the signals work (except the broken one) the starter kicks over, I have power to my coils, and no smoke comes out of the harness. When I get back I'll fill and bleed my front brake, fix my bad signal and see about rebuilding my carbs.

The bad signal shows up at the Turn Signal indicator.

Power to my coils. The battery is really low, voltage at the battery is the same as in the pic.

I can't wait to get this thing fired up!

thrutheframe · « **Reply #9 on:** August 28, 2011, 11:55:22 AM »

The wire harness is all sorted except double checking the routing when I put the tank back on. I don't have/ couldn't find the blinker buzzer so that line is dead and the two blues and the white are still hanging until I put the headlight in.

thrutheframe · « **Reply #10 on:** August 28, 2011, 01:22:44 PM »

I have the carbs all ready to dip. It all came apart real nice and looked really dirty.

My carb kits didn't include the 8 o-rings for the crossover T's or the 4 for drain screws. I'm going to sort through the bits now to decide what gets dipped and what gets washed with soap.

thrutheframe · « **Reply #11 on:** September 03, 2011, 08:22:51 AM »

I put 2 of my carbs in the can of carb cleaner for two days and wasn't thrilled with what they looked like when I pulled them out. All of the aluminum parts were covered in a grey sludge and none of the parts were cleaned. I guess I had some bad carb cleaner? Has anyone ever seen this before? I bought two cans of spray brake cleaner and I'm going to hit them with that.

Stev-o · « **Reply #12 on:** September 03, 2011, 09:31:26 AM »

Looks like a nice project. Good call on pulling the carbs and doing a good clean, doubt it would have run right.
Like the blue color, but as you probably know, it was not available stock on a K4 (Planet blue was on the K5).
Coincidently, the PO of my K4 painted it blue too.

thrutheframe · « **Reply #13 on:** September 03, 2011, 09:33:15 AM »

Brake cleaner wasn't really taking the stuff off so I figured I'd pre-soak the second one in sea foam. The sea foam broke it up better. I cleaned the sea foam off with the brake cleaner then hit them with a brass brush. I'd love to have them soda blasted but money is tight right now.

thrutheframe · « **Reply #14 on:** September 03, 2011, 10:54:02 AM »

Quote from: Stev-o on September 03, 2011, 09:31:26 AM

Looks like a nice project. Good call on pulling the carbs and doing a good clean, doubt it would have run right.
Like the blue color, but as you probably know, it was not available stock on a K4 (Planet blue was on the K5).
Coincidently, the PO of my K4 painted it blue too.

Thanks Steve O. The paint on this bike is super bad. I've got my eye on a nice tank on eBay... it's blue too, I'm definitely going to replace the side covers too, probably with some Frankenstuff covers. I have two planet blue 360T's, both 75's, its one of my favorite colors. I'm not sure where I'm going with this thing but I'd like to eventually go Flake Sunrise Orange.

thrutheframe · « **Reply #15 on:** September 03, 2011, 12:53:15 PM »

thrutheframe · « **Reply #16 on:** September 03, 2011, 05:22:52 PM »

I ran out of brake cleaner so I only got 3 of them done. I have to drive to Indy and work tomorrow so I'll have to get back to this later tomorrow. The 3 I did look pretty sweet for not having soda blasted them.

thrutheframe · « **Reply #17 on:** September 03, 2011, 05:28:49 PM »

I just realized that I have the carb bowls swapped around... Before I re-rack em I'll flop all that around and make sure the two brass screws are on the outside.

thrutheframe · « **Reply #18 on:** September 13, 2011, 03:57:08 AM »

I have the carbs all back together. My ebay orings never showed so I had to go to Small Pro Hardware and get them. I should have gone there first, they have just about everything else that you would need that isn't specifically a motorcycle part.
My seat is coming this week thanks to forum member BR. $100.00 plus the shipping. I still have a ways to go epsecially since summer is ending soon and I have to work this coming weekend.

thrutheframe · « **Reply #19 on:** September 13, 2011, 03:59:57 AM »

A few pics.

thrutheframe · « **Reply #20 on:** September 17, 2011, 02:51:29 PM »

Ready to mount.

Stev-o · « **Reply #21 on:** September 17, 2011, 04:10:38 PM »

Quote from: thrutheframe on September 17, 2011, 02:51:29 PM

Ready to mount.

Can be tough to tune with stacks on it...

thrutheframe · « **Reply #22 on:** September 17, 2011, 09:21:23 PM »

Quote from: Stev-o on September 17, 2011, 04:10:38 PM

Quote from: thrutheframe on September 17, 2011, 02:51:29 PM
Ready to mount.

Can be tough to tune with stacks on it...

Those are new stock boots, I have the stock airbox and a new air filter. I just put those on there cause they look cool in the shot. Thanks for checking out my project. I have a long way to go before this bike is a reliable rider, but I think I might actually fire her up soon.

I got the carbs mounted and the throttle cables hooked up. It wasnt easy but I greased them up just a tiny bit and rocked them back and forth while pulling on both sides from the front. I also got the wire harness fine tuned and wire tied in place.

I bought a new tach gear seal but something isnt right, the tach cable wont go into the well so that the screw passes thru the notch. It looked like the olld seal was missing but maybe I missed it in the poor light where I'm working.

thrutheframe · « **Reply #23 on:** September 23, 2011, 03:11:45 PM »

I got this gem of a gas tank off of eBay. It's clean as a whistle inside and the paint looks pretty darn good. That gives me the motivation to get the airbox on... Knowing that I have a clean fuel tank to run is a big relief.

thrutheframe · « **Reply #24 on:** September 25, 2011, 12:47:00 AM »

I got my airbox all cleaned up today. The years and years of crud and dried gas came right off with some Dawn dish soap and a scrub brush. I'm convinced that at some point this bike sat with the floats stuck open and gas pouring everywhere.
I put it all back together and realized that I hadn't ordered the gasket that seals the two halves. DOH!
Sorry no pics from today, I'll post a pic of the whole thing reassembled when the gasket arrives.

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Author Topic: 1974 CB750K4 wrench and ride (Read 16161 times)