Topic: 72' CB750K2 Resto-Mod

[calj737]

Probably about $10/$15 if I recall. They were part of a larger order so I was already having quite a bit done.

[FridgeRaider]

So I finished up the carbs. I had to replace one of the carb bodies but everything else worked well with new Honda gasket kits and powder coating the little parts to match. I did find that one of the float posts had been repaired, it's the only thing that the PO had done that was actually decent work.














New 6mm grease zerks for the swing arm bolt. Simple and cheap upgrade to cut new threads, clean out, and replace.





Here's the bad news: I need help determining what is salvageable for the engine's top end. Once I pulled the valve cover, it was apparent that who ever worked on the engine last did not care to put bolts back in or the right ones for that matter. The four bolts that hold the cam towers in place were re-threaded to SAE 1/4". I cant imagine the cam journals faired well while missing 3 bolts to hold them in place.







Cam journals





Broken Cam lobe





Scoring on the rocker shafts. The following is the worse of them, still usable?



What would make the rockers discolor like this? Oil starvation and then overheating?





Can the head be saved? I think I have the four studs that will go back in-line for the cam journals, what can I do for the now SAE 1/4" threads that are supposed to be 6mm?



The PO used some sort of glue on all the gaskets and I'm finding it throughout the entire motor in bits and pieces. 

[754]

Clean your oil passages, looks a bit oil starved. the blue rockers. one side or both?
if you are handy on a lathe you can make studs, 1/4 inch one end. 6 mm on the other.

[calj737]

The "blued" rocker is indeed from overheating. Oil starvation issues probably due to the gasket adhesive you found being sucked up into the galleys.

I would drill and insert a TimeSert for the cam towers and use new, proper bolts. Re-tapping for 1/4 within a 6x1.0 hole severely weakens the threads. Its not distinctly different enough to re-profile the minors, only enough to raise the majors.

Your cam is shot. The shafts look usable to me. I'd treat them with DFL as long as they are still straight and true (got the ability to check their runout?) Cam journals while dicey, probably would be okay for a street motor  If you want, when I collect the cylinders I can grab the head and have my guy make a determination.

[riverfever]

Sorry you found all the issues with the motor.

The carbs turned out super! Great job.

[FridgeRaider]

Clean your oil passages, looks a bit oil starved. the blue rockers. one side or both?
if you are handy on a lathe you can make studs, 1/4 inch one end. 6 mm on the other.

No lathe 

Sorry you found all the issues with the motor.

The carbs turned out super! Great job.

Thanks! The motor should make for an interesting challenge....

The "blued" rocker is indeed from overheating. Oil starvation issues probably due to the gasket adhesive you found being sucked up into the galleys.

I would drill and insert a TimeSert for the cam towers and use new, proper bolts. Re-tapping for 1/4 within a 6x1.0 hole severely weakens the threads. Its not distinctly different enough to re-profile the minors, only enough to raise the majors.

Your cam is shot. The shafts look usable to me. I'd treat them with DFL as long as they are still straight and true (got the ability to check their runout?) Cam journals while dicey, probably would be okay for a street motor  If you want, when I collect the cylinders I can grab the head and have my guy make a determination.

You lost me at minors and majors. I will most likely install a Timesert, this was what I was hoping to confirm that I could do. So far the rest of the head looks to be in good shape.

I was thinking of upgrading to a mild street cam, this makes for an easy decision now, any suggestions? and as you suggest, I will try to make all the other parts works. I'm hoping not to have to send the head off as well. Thanks for the offer though.

[FridgeRaider]

This past week has been interesting. I finished tearing down the engine and thankfully didn't find any other obvious damage to the internals. I know there is some hiding somewhere because I found some sizeable chunks of metal when I first dropped the oil pan. For right now the engine work is on hold.



Upper


Lower


How I'm keeping the lower crankcase bolts organized.


Here's the list of parts that I went ahead and purchased for the bike, since everyone knows it's the holiday of spending:

• Cruzin_image 836 bigbore kit
• Diamond 530 Chain 102 Link
• Hagon Shocks, Classic I w/ SS Shroud
• CycleX Super Studs
• Kibble White HP Valve Springs
• Left & Right Reproduction Handlebar Switches
• OEM Honda Horn Assembly
• Motogadget M-unit
• Elan's Oil Pump Gasket Kit

I wish I could have supported forum member NobleHops with his new Ikon Shocks venture but I love the close-to-stock look of a shock shroud and Ikon's cheapest option was $500+. This was even with his member discount. I went with the more "budget friendly" Hagon option. After a 10min conversation over the phone telling the guy what bike they were going on and what style of riding was to be done, they ended up being $289 shipped to my door. I'm quite satisfied with the purchase so far.







I did drop off my frame, swing arm, and chain guard at a local powdercoating place since those parts are too big for my setup. For the most part I thought these guys did a competent job, all threads where masked and they asked me what else needed to be. My only complaint is that they taped off the serial number and left it bare. They did tell me this beforehand and that they do it so as not to lose it under the powder. 



Steering stem got tapered bearings from all-balls




Installing brass bushings in the swingarm. I would suggest this method as opposed to hitting them with a hammer




Since I powdercoat and sandblast in my garage, I decided to transport all the pieces to my father's garage and put the bike together there. That way I can keep the bike clean throughout the entire assembly process. My garage contents forever have a fine layer of dust over them. 

[calj737]

Brush some clear nail polish over the serial number and that will keep the bare metal protected from the FL humidity.

[SOHC4 Cafe Racer Fan]

That bare square looks a little funky.  I'm surprised they do that.  I guess they like to lay the powder on thick.

[FridgeRaider]

Brush some clear nail polish over the serial number and that will keep the bare metal protected from the FL humidity.

I was going to pick up some decent model paint to do some touch up work. I figured I could find a black close enough so it doesn't stand out like it does now.

That bare square looks a little funky.  I'm surprised they do that.  I guess they like to lay the powder on thick.

They did lay it down thick, not sure if that helps durability or not. As long as it last 20 years, I'll be content.

[SOHC4 Cafe Racer Fan]

They did lay it down thick, not sure if that helps durability or not. As long as it last 20 years, I'll be content.

Not sure either -- if it makes it more durable or more prone to chips (or simply just a little heavier).  I doubt it will have any significant effect.  Keep on keeping on!

[FridgeRaider]

I've been working on some minor parts; engine covers and the likes. here's some pictures.







I took an angle grinder to the battery box and drilled some new holes so that i could mount an M-unit, Rick's Reg/Rec combo unit, and reproduction starter solenoid off of it. The idea is every electrical part will be either upgraded or new reproduction parts to keep the same look (ex: electronic ignition, all turn signals and stems, key lock). I want wiring up the bike to be smooth sailing and hassle free, if there is ever such a thing with electrics.


 


The swing arm ended being an absolute pain to powdercoat. It barely fits in my small oven and took me three tries before being able to get it in without screwing up the dry powder. The first time, I straight up dropped it. That's why there a good deal of powder on the floor in the pic. I might have to upgrade my oven when it comes time for the crankcase halves.




On a different note: Does anyone know if Slingshot Cycles (site sponsor for braided brake lines) has a listed phone number somewhere so that I can contact them directly? I sent an email last week inquiring about purchasing a dual disc setup and still haven't had any response. I've bought from them before but went directly through the website.

[calj737]

PM sent re: Sling-shot

[FridgeRaider]

PM sent re: Sling-shot

Thanks Cal! I have the Cruzin_image 836 pistons in the mail. I should be getting close to the point where I can take you up on your offer to transport them to your machinist the next time you swing through my part of town. Should I hold off on powder-coating the cylinders until after I have them bored out?

[calj737]

I'd coat before machining. I'll be there the week of 12/19 so we are good on crossing paths.

[FridgeRaider]

I'd coat before machining. I'll be there the week of 12/19 so we are good on crossing paths.

Perfect! Thanks for the info and assistance.

[SOHC4 Cafe Racer Fan]

Cal the Cross-Country Cylinder Courier!  Mighty nice of you.

[FridgeRaider]

I got a response from Shaun @ Slingshot cycles and he did ask a couple of questions about how I'm going to run my setup. Then plan was to run the lines directly to the caliper and bypass the standard hardline. I removed the restricting insert on the second caliper prior to rebuilding. Should I have done that on the first one as well? I'm still a little fuzzy on it's purpose in the first place.

[bill440cars]

      Do I ever like your progress with this build! You accomplished quite a bit, since I was here last. Awesome work too. Really liking your Powdercoating! That is going to be One Fine Ride, when finished! Too bad about the issues you found, but I am glad that things can be worked out. Nice of Cal to help out like he is too. Some more of the "Family" atmosphere, around here, that I enjoy so much.  You will have every right to be proud of this bike, when finished. 

[timbo750]

I got a response from Shaun @ Slingshot cycles and he did ask a couple of questions about how I'm going to run my setup. Then plan was to run the lines directly to the caliper and bypass the standard hardline. I removed the restricting insert on the second caliper prior to rebuilding. Should I have done that on the first one as well? I'm still a little fuzzy on it's purpose in the first place.

I did a twin disc conversion using the same brackets you have. I used the standard hard lines past the forks on both sides, mainly so that I didn't have to sucure a flexible line past the forks and the flexible line would most likely have to around the forks. I wouldn't worry about the size of the bit inside the caliper, its there so that the solid line will seal and I can't imagine it would affect flow too much as its more about pressure. Just upgrade the master cylinder and braided lines, also a bit cross drilling helps.

[calj737]

I got a response from Shaun @ Slingshot cycles and he did ask a couple of questions about how I'm going to run my setup. Then plan was to run the lines directly to the caliper and bypass the standard hardline.

On my 550, I had Shaun build me a custom braided line because of the custom triple. And I wanted to ditch hardline as well. But, due to the angle of caliper fitting, using braided line only (in my application on the 550, 750 may be different) would have created a kink in the line. Thus I have a short section of hardline with a rapid 90* transitioned back to braided. Allows proper alignment and flow, and is fairly discreet.

I don't know if this was discussed between Shaun and you?

[edwardmorris]

Evan runs his lines directly into the caliper on his mostly stock 750. They're probably from SSCycles too.



http://forums.sohc4.net/index.php/topic,136061.msg1803704.html#msg1803704

[calj737]

That uses a short hardline, Ed.

[FridgeRaider]

Hey guys, thanks for the responses and support. I didn't realize that if I ran the braided brake lines straight to the caliper that I would have to run the lines on the outside of the forks ......and I just don't like that look. So now I'm back tracking to running hard-lines between the forks on both calipers. Which leads me to more questions. It looks like OEM hard-lines are still available for around $7, are they easy enough to manipulate so I can bend one to work on the mirrored caliper side? SSCycles sells a mirrored one for $30 the last time I checked, but I'm trying to save some money where I can. Also for the restricting insert, I removed it from the second caliper and either tossed it or misplaced it (oops). Will I absolutely need it in that caliper? If so, does anyone have one lying around they are willing to sell me. 

[markreimer]

I'm not sure if this is the same situation as you, but I have a K4 and am running a braided line from my master cylinder directly into the caliper, running the line on the inside of the fork leg, works 100%. It's not a dual disc setup, just the standard single disc. Was very easy to setup.