Author Topic: '78 CB750K cafe project build (Read 12740 times)

afkrejci90 · « **on:** April 14, 2012, 05:48:00 PM »

Picked this up off of craigslist for cheap, ran good but started to develop some leaks so it became time for a rebuild with some upgrades.

afkrejci90 · « **Reply #1 on:** April 14, 2012, 07:19:18 PM »

Here are some pics, more to come.

MasterChief750 · « **Reply #2 on:** April 16, 2012, 08:48:44 AM »

looks like you got some work to do good luck

Blitzburgh207 · « **Reply #3 on:** April 16, 2012, 09:28:01 AM »

Good luck man! I got some spare parts for a 78 around if you need anything!

afkrejci90 · « **Reply #4 on:** April 16, 2012, 10:14:20 AM »

Thanks! Everything is there on the bike but I may need some new parts the more I dig into this.

afkrejci90 · « **Reply #5 on:** April 22, 2012, 08:22:12 PM »

Split

afkrejci90 · « **Reply #6 on:** May 04, 2012, 07:29:52 AM »

Case is cleaned up and ready to be bored.

Blitzburgh207 · « **Reply #7 on:** May 04, 2012, 08:59:40 AM »

You gonna throw some HD studs in there?

afkrejci90 · « **Reply #8 on:** May 04, 2012, 02:37:52 PM »

Eventually, those are just in there if the machine shop needs to set the cylinders in there, if not they can take em out.

afkrejci90 · « **Reply #9 on:** June 15, 2012, 07:56:04 AM »

Still waiting for the machine shop to stop slacking off and finish the engine already. But in the mean time I'm working on the frame and body components.
I want to add another disc brake to the front, what do I need to do beside bolting on a caliper and disc? Are there any modifications I have to make first?

Blitzburgh207 · « **Reply #10 on:** June 15, 2012, 08:25:35 AM »

You're going to need to shim the caliper carrier arm (I actually took some material off the fork on the lower bolt as well) and modify your speedo drive plate. I think I had to make slots in my rotor as well.... It's not too hard. You'll also need a larger master cylinder and brake lines. I got a used CBR MC for like 50 bucks on ebay and it works great and looks good. Got the braided lines from Slingshot cycles in the For Sale section and I'm very happy with them (wouldnt mind a couple extra inches though

) See this link for more info but doesnt really go into detail on the mods. Definitely worth the time/effort IMO.

http://www.sohc4.net/index.php/dualdiskconversion-cb750/

If you look closely at this pic you can see where I cut the speedo drive down but left tangs on either side of it and notched the rotor to accept them.

afkrejci90 · « **Reply #11 on:** June 18, 2012, 03:07:50 PM »

Got my Gordon frame kit installed and just needs to be welded in.

afkrejci90 · « **Reply #12 on:** July 08, 2012, 09:09:55 PM »

Started working on a custom cafe seat and tail since there are not too many options for the K8. I wanted to keep the hinges so I could switch back to the stock seat if I ever wanted to. Made a custom pan out of diamond plate and started to build up the tail section and shape it out.

Its going to need a little more work , its only about half way done. I want it to compliment the lines of the tank so it looks like it flows from the tank.

afkrejci90 · « **Reply #13 on:** July 10, 2012, 06:43:47 PM »

Worked on it a little more tonight and I'm pleased with the results.

seat cover man · « **Reply #14 on:** July 10, 2012, 08:26:16 PM »

looking sweet man

afkrejci90 · « **Reply #15 on:** July 12, 2012, 04:45:58 PM »

Here is some of the parts thats going into this, along with a DP327 cam.

KB02 · « **Reply #16 on:** July 12, 2012, 04:48:09 PM »

OOOOooooooooooooooooooo........................

afkrejci90 · « **Reply #17 on:** August 13, 2012, 02:25:30 PM »

So I got my engine back today. After about three months of its possession by this fly by night machine shop, it comes back to me without any work done. I called the guy many times throughout the summer to check on the progress. He led me to believe he was working on this slowly and until recently only had to bore the sleeves and it would be finished. Wow was I wrong, he never touched it the whole time he had it. What make it worse, a piece of metal on the points cover was cracked during the separation of the cases. It wasn't in danger of falling off, just had a stress crack in it. When I gave it to him it was still there. Now its gone. Hopefully this can be easily repaired by a skilled welder. It irritates me most that he wasted my time and never worked on it and breaks a piece off of it. Although its good he didn't work on it now after hearing about his work from other shops. He was only going to bore the cylinders based off the measurement of one piston. Definitely going to send any machine work to APE or Cycle X from now on.

afkrejci90 · « **Reply #18 on:** August 28, 2012, 11:58:26 AM »

So I got my crank back from APE today and this thing looks great. Still a long way from getting it assembled. Just started work again so now I'll be able to get back to working on this at a steady pace.

Mercutiojb · « **Reply #19 on:** August 30, 2012, 12:49:29 PM »

Subscribed!

afkrejci90 · « **Reply #20 on:** October 19, 2012, 07:12:50 PM »

Took advantage of the rainy day to get the head cleaned and ready for a 5mm valve train conversion and MRieck's port job.

Also got the crank back from APE

afkrejci90 · « **Reply #21 on:** October 25, 2012, 10:40:25 AM »

Here's some pics of the teardown process that I forgot to upload.

Before I heard about the bike on the side method. This didn't work. Ended up jacking it up from underneath and maneuvering it out.

Cleaned up

Base for the custom seat

afkrejci90 · « **Reply #22 on:** October 25, 2012, 10:49:55 AM »

More progress on the seat mold. Going to redo it in floral foam since this stuff is a pain to shape or sand.

SOHC4 Cafe Racer Fan · « **Reply #23 on:** October 25, 2012, 01:30:33 PM »

That diamond-plate seat base might be overkill and overweight. It should definitely do the job, but you might want to switch to something lighter, assuming it is steel.

afkrejci90 · « **Reply #24 on:** October 25, 2012, 02:16:17 PM »

Its aluminum diamond plate, a regualr flat sheet would have been to flimsy and I don't have a welder to fabricate a frame for one.

SOHC4 Cafe Racer Fan · « **Reply #25 on:** October 25, 2012, 05:41:50 PM »

That makes sense.

afkrejci90 · « **Reply #26 on:** February 05, 2013, 01:36:03 PM »

Getting ready to send the head out for work, but as you can imagine there is a good layer of carbon built up on it. I've put it through a parts washer many times as well as spraying it down with carb cleaner, but it hasn't come out clean. What could I use to really get this clean?

Blitzburgh207 · « **Reply #27 on:** February 05, 2013, 02:02:25 PM »

Soda blast or bead blast it?

afkrejci90 · « **Reply #28 on:** April 27, 2013, 03:38:13 PM »

Just picked this up the other day. Now I can clean my head off and do just about any part on the bike except the frame. Well worth it.

deafcaferacer · « **Reply #29 on:** April 28, 2013, 07:55:38 AM »

Wow.. I don't suppose that's available at any local home depot for a reasonable price??

afkrejci90 · « **Reply #30 on:** April 28, 2013, 08:43:19 PM »

Quote from: deafcaferacer on April 28, 2013, 07:55:38 AM

Wow.. I don't suppose that's available at any local home depot for a reasonable price??

Harbor Freight for about ~$200 everything included except the media.

afkrejci90 · « **Reply #31 on:** June 23, 2014, 09:14:51 PM »

This project went on the back burner for quite awhile. Finally got the money saved up for Mike Riecks awesome head work after starting school again. Now that the most expensive part of this build is complete I've got the motivation again to get this thing finished. Working on cc'ing the chambers for custom pistons.
Here is a few shots of the head, quite a shame to hide this in the engine.

Using the Kibblewhite 5mm conversion with oversize intakes.

afkrejci90 · « **Reply #32 on:** August 12, 2014, 04:43:34 PM »

Finished installing the Kibblewhite 5mm conversion kit. Working on the chambers tonight to get them CC'd and molds made so I can get my custom pistons.

afkrejci90 · « **Reply #33 on:** June 04, 2015, 09:01:49 PM »

Since my long hiatus from this project, I now have most of my big money items and am ready to get this thing finished. I sold off my original set of 1000cc JE pistons to go with a high CR custom set from Dynoman. Made the molds and got them sent off to Dynoman. The first mold was my bad attempt and mold making, didn't come out so well. Waiting for the pistons to come in some time next week. Once those are in, the cylinders, top case, and transmission are off to APE. Also pulled the trigger on a set of weber 40 DCOE carbs. Not sure on how to get everything connected together yet but some custom machining work is in order.

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Author Topic: '78 CB750K cafe project build (Read 12740 times)