Topic: My 77 CB750K Project Update

[Dyrden]

Nice! Is that an Avon Roadrider 100/90-19?

[mrjack55]

Nice! Is that an Avon Roadrider 100/90-19?

Close, it's a 3.25x19.

[lucky]

That NOS seat is gorgeous!  Nice find!

I agree - jetting for pod filters is a real bear, it can be done but it's a lot of work to get it right.  The stock air box works really well, no issues if you get caught in the rain, either!

It is not a real bear to rejet the carbs.
Just remove the carbs take out  and install the larger mainjets.

[mrjack55]

It is not a real bear to rejet the carbs.
Just remove the carbs take out  and install the larger mainjets.

Maybe, but I don't hate the stock airbox enough to go through all that.  Let's be honest, it's never that easy. 

[mrjack55]

Update: August 17, 2011
So I took her out for a ride today.  Nothing major, just 7 miles around the hood.  Figure I'd stay close to home.

She's a little shaky.  The forks are very soft, so I need to either add more fluid or air.  After the trip, I noticed that my brand new tri-bar headlight melted.  Another quality product from that English bloke in SoCal.

Here are some before and after shots.

BEFORE:


AFTER:


BEFORE:


AFTER:

[mrjack55]

Oh, and here are a few shots of the melted tri-bar. 
The black dot should be front and center.


It's a little hard to see, I know.


He's a pretty stand up guy.  Told me to send it back for a refund, then hung up on me. 

[mrjack55]

Update 8/31/11
I didn't get any pics because, well they would be pretty damn boring, but I added spacers to preload the springs.  She would nose dive pretty badly on braking and in turns.  I had four .5" composite spacers lying around, and I bolted two together to give me the two 1" slugs for each fork. The springs are pretty worn out, so I was comfortable with 1" to start.  Yes they were a complete PITA to get in, but wow what a difference.  I also bumped up the Hagon shocks one notch.  She rides pretty nice now, but I'm sure that if I took the time to truly measure and adjust the sag it would be even better.  I'm going to start saving my pennies and maybe this winter I'll be able to afford Race Tech springs and gold valve emulators.  That should help smooth things out very nicely.

While fighting with the forks and getting the caps back on I broke one of the turn signals.  They are plastic, so no real surprise there.  I rigged it back up so I can still ride, but I did order new aluminum ones from Lockhart Phillips.  I also grabbed a set of bar end mirrors off of feeBay.  Once I get everything in, and put on, I'll add a few new pics.

[Dyrden]

Nice.  Im about ready to throw my fork back together.  Im accustom to modern sport suspension so I was wondering what weight and how much oil you used.  I also preloaded the springs about 2cm but rather than install spacers ontop of the springs I installed them on the pumping rods to decrease the travel and increase the preload at the same time.

[mrjack55]

I was wondering what weight and how much oil you used?

Thanks Dryden. 
I used 5.4 Oz. of 5W fork oil.  I have no idea if this is the right set up or not yet.  I still need to experiment with the volume and the weight.  I think it rides "ok", but I think it can be better.

[mrjack55]

Update 9-13-11

So, last night I was in a pretty crappy mood thanks to a bad day at work.  The fiance was out to dinner with a friend, which left me home alone board and cranky.  Only one, well 3 cures for that.  I ordered a pizza, grabbed a few PBR's and headed out to the garage.  Next thing I know, I was stripping the whole thing down.  I did order a big bore kit, so my thought was; I have to get the motor out anyway, why not go all out.  The question now is, do I take the grinder to the frame or not?  Do I restore it, go full out cafe, or some other way?  I'm not sure yet.  I have a lot of clean up to do first.

[theofam]

I'm in your same boat on my '78 750K.  After getting it back together in April, it was leaking a bunch, so I decided to completely tear it down last week.  Everything is off to powdercoat, and I plan on diving into the motor tomorrow.

Only you can answer the stock, cafe, brat, digger, chopper question.  I've learned it depends largely on your mechanical (and tool) availability.  I tore down a CB550 nearly two years ago to cafe and it has become a garage lizard due to a need (and my inability) to weld, fabricate, fiberglass, etc. 

Keeping the 750 stock has been a much easier endeavor.  What comes off goes back on, and it fits!  Downside is finding some of the stock parts.  Your call.  Just have fun doing it!

[mrjack55]

I'm in your same boat on my '78 750K.  After getting it back together in April, it was leaking a bunch, so I decided to completely tear it down last week.  Everything is off to powdercoat, and I plan on diving into the motor tomorrow.

Only you can answer the stock, cafe, brat, digger, chopper question.  I've learned it depends largely on your mechanical (and tool) availability.  I tore down a CB550 nearly two years ago to cafe and it has become a garage lizard due to a need (and my inability) to weld, fabricate, fiberglass, etc. 

Keeping the 750 stock has been a much easier endeavor.  What comes off goes back on, and it fits!  Downside is finding some of the stock parts.  Your call.  Just have fun doing it!

It's a sickness, I'm just not happy if I'm not building.  Don't get me wrong, I love riding, but I get a bigger thrill out of the build.  When Jenn came home the night I started the tear down, I had a huge ear to ear grin on my greasy face.

At the moment I'm thinking about a streetfighter build with a mono shock swing arm set up.  Should be fun, and interesting to explore.  I thought it might be nice to do something a little different than the usual cafe or stock restore.  After all, it is a K7 and everyone seems to hate them anyway.  So if I cut it up, no big deal.  Right guys?

There are a lot of great looking bikes on this forum built by some very talented people.  I have a lot of inspirational pics to look at.  Not to mention all the professional advice.

[Dyrden]

Mines a K7 and its chopped up and in my dinning room.  BTW, I think the 'hate' stems from the fact they are just different enough to be a pain in the ass when sourcing replacement parts.  For what its worth, the front brake is stronger and the engine is a little better.

[mrjack55]

Update: 9/18/11

So today I finished the strip down.  All that is left is to remove the engine.  I need to find someone with a strong back to help me do that as the engine happens to weigh more than I do.  I also need to get a motor stand so I can work on the motor more easily.  Here are a few $@!ty cell phone pics.

[Dyrden]

Nice! Im a little ahead of you.  My engine is pulled and in a cheap harbor freight stand.  I spent about 4 hours today cleaning the engine for probably the 3rd time.  Its getting there.  I sanded down the fins on the head to even them out and then starting polishing the top of the last fin under the valve cover.  I decided to wash the dog too since at that point my dog was dirtier than my engine.

[mrjack55]

Nice! Im a little ahead of you.  My engine is pulled and in a cheap harbor freight stand.  I spent about 4 hours today cleaning the engine for probably the 3rd time.  Its getting there.  I sanded down the fins on the head to even them out and then starting polishing the top of the last fin under the valve cover.  I decided to wash the dog too since at that point my dog was dirtier than my engine.

3rd times a charm?  Probably not if you're anything like me.  I can't wait to get the into the motor.  My big bore kit should be here this week, so I have that to look forward to as well.  I plan on hitting HF tomorrow for the motor stand.

[mrjack55]

10/03/11
The engine is out of the frame and disassembling has begun.  Get ready for a lot of pictures folks.








In the next post things start to come off. 

[mrjack55]

First out, the plugs.  Hum, #3 looks a little rich.


Here's a peek into the #3 exhaust port.


Looks like someones been here before.


A little gunky in here.


Continued

[mrjack55]

The first look inside.




I think there was a bit of a gasket leak.




Continued

[mrjack55]

The underside of the head.


Number 1 and 2 chamber.


Number 3 and 4 chamber.


Quite a few miles on these guys.


Continued

[mrjack55]

So here it is as of right now.


I have the 836 big bore kit, so most of this will not be reused.  I also plan on getting the head done up with new valves, guides, port and polish.  If you guys see anything funky in there, please feel free to shout.  It looks pretty good considering her age and close to 30K on the clock.  I do plan on splitting the cases to check everything out, but I don't think I'll be doing to much in there.  I'll know more tomorrow. 

[lucky]

Just wanted to let you know that the weld shown below needs some attention.
It is incomplete. You can see where the butt joint is, and the welder must have been using one hand waving the welding gun around.

I would carefully sand the area of that weld (NOT grind), and then reweld that unfused gap. TIG would be best. Disconnect your battery terminals first.

I would check all of those tubular weld connections just to be sure.

[mrjack55]

Just wanted to let you know that the weld shown below needs some attention.
It is incomplete. You can see where the butt joint is, and the welder must have been using one hand waving the welding gun around.

I would carefully sand the area of that weld (NOT grind), and then reweld that unfused gap. TIG would be best. Disconnect your battery terminals first.

I would check all of those tubular weld connections just to be sure.

Thanks for the heads up.

[bikebitzofvt]

Boy, looks like you've got some fun ahead.  Are you replacing the cam while you're here?  I'd also reccomend new cam chain guides & rollers, 'specially with 30K on 'em.

That #3 plug looks like oil fouled, not rich, probably a valve seal.  But, you're rebuilding any possible culprit, so you'll be good there!  Looking over the pics again the #3 intake valve looks wet with oil, so the valve seal is the likely suspect.

I would get that frame redone while it's all apart.  I looked into making some gordon style frame kits (allow removal of the top end while engine is still in the frame) just couldn't come up with the capital to get started.  If you could find one of those now would be the perfect time to install one!  Still gotta wonder why the PO did that in the first place!?!

Here's an install thread of one of the kits I mentioned : http://forums.sohc4.net/index.php?topic=43997.msg457716#msg457716

Keep up the good work!

Tom

[mrjack55]

Boy, looks like you've got some fun ahead.  Are you replacing the cam while you're here?  I'd also reccomend new cam chain guides & rollers, 'specially with 30K on 'em.

That #3 plug looks like oil fouled, not rich, probably a valve seal.  But, you're rebuilding any possible culprit, so you'll be good there!  Looking over the pics again the #3 intake valve looks wet with oil, so the valve seal is the likely suspect.

I would get that frame redone while it's all apart.  I looked into making some gordon style frame kits (allow removal of the top end while engine is still in the frame) just couldn't come up with the capital to get started.  If you could find one of those now would be the perfect time to install one!  Still gotta wonder why the PO did that in the first place!?!

Here's an install thread of one of the kits I mentioned : http://forums.sohc4.net/index.php?topic=43997.msg457716#msg457716

Keep up the good work!

Tom

Thanks Tom.
Yeah you hit the nail right on the head.  It's a valve seal for sure on #3.  It is pretty easy to see in the pictures, not to mention in person.  But, I do plan on a total head rebuild so problem solved. 

I took a good look at the cam, and it's pretty worn.  So yes, I will be replacing it as well.  Not sure If I'll go with a Web or maybe a K0 cam.  I'll have to see what my budget looks like. 

I was looking into the Gordon frame kit back when I first found the welds.  Many old school chopper and race guys used to cut this section out and never replace it.  Not so sure I feel safe doing that, but I'll just touch up the existing welds and leave it be.
I'll be doing a lot of cutting and welding as I'm leaning heavily towards a streetfighter build.  Something very much like Rodan, the Brian Fuller build that pi$$ed off the SOHC4 world.  Not to mention won a world championship.  But, that's all been covered in another 10 or so threads.  Should be fun!