Topic: 1978 CB750 Restoration

[Juan1]

This is my first full tear down.  I've rebuilt top ends, carbs, brakes, master cylinders and repaired various parts before, but this will be the first time I've had the all of the aforementioned parts off the bike at the same time. 

Background: This bike was driven as a main means of transportation by the previous owner who racked up 12k miles on the bike.  3-4 years ago he purchased a car after the front brake started binding, parked it near his boat at the harbor, covered it, and it has sat there rusting ever since. 

The Plan: Restore the bike to nearly new condition.  This will be done by rebuilding the brakes, top end, carbs and master cylinder.  On the cosmetic front I will restore what I can and replace the rest.

Here Rusty is as she sits now:

[Wiggy_NZ]

Nice find..  at only 12k miles why is there a need to do a top end rebuild?  Seals on the master cylinder and while working on the front brakes replace the slave cylinder O ring also.  Fork seals ok?  If you do the fork seals polish up the bottom of the forks with a grinder and buffing wheels.  Reasonable easy but can be a bit of a messy job.  Take the side cases of and buff them up also, if you are in the mood.  I have a 750 K5 that has been a winter project for me and so far everything is sweet, except fo one carb which is coming from the US of A.  Soon my bike will make noises 

Good luck and welcome on board

[Juan1]

42k miles are on the bike, but 12k of that is from the P.O.  I'm not sure about the fork seals and fork oil, so I'm going to replace them.

Vinegar, oxalic acid, and polishing wheels are about to become my close friends.

Thanks!

[Juan1]

Taking pictures and labeling bolts transformed my teardown into a two day process.  Here she is after teardown day 1.  Day 2 will have to wait until next weekend.

[Bankerdanny]

It's your dime and your time. But personally I am in favor of getting a bike running first before I tear into the engine.

The 750 engine is a pain in the ass to do the top end since it has to come out of the frame to get the head and jugs off.

Depending on how well it was treated by prior owners, even at 42k the engine could be quite solid.

[Juan1]

I am with you Bankerdanny, but the engine is being pulled so I can powdercoat the frame anyways.  If the engine is out, I might as well rebuild the top end.  Plus the bike has that insipid head gasket leak.

[Juan1]

Here are some before and after pictures of various parts. 

Airbox before and after apply peanut oil, giving it 5 minutes, and wiping it as dry as possible.  In the before picture the box had just been washed to remove all dust.

[Juan1]

Carb Boot before and after pics surrounding my usage of the boiling water and wintergreen oil trick.  Note that the hard-as-a-bone side barely softened, while the slightly soft side became markedly improved.

[Juan1]

Here are my vinegar soak before and afters.  My process was a 2 day vinegar soak followed by a brass brush, then rinse thoroughly with water.  Finally I used some naval jelly to undo the flash rusting.  Then I rinsed with water and wd40'd everything.

In the final pic, the close up, note that the chrome on the top of the rear fender cleaned up, but still doesn't look great.  Hopefully polishing will clean up the section not hidden by the seat.  Next weekend I will spray paint the underside of the fender and the hidden topside with some of Eastwood's rust encapsulator paint to try to prevent the red cancer from returning.

[Juan1]

It is becoming clear that rust may have undone my plan for this bike. My original step 1 of cleaning everything up and getting the beast running should work.  My step 2 of then ebaying a 75-76 tank and seat, painting the tank and sidecovers, and then riding around on a clean looking bike is where the problem lies.  The rims, especially the front one, are too pitted to be called good condition.  The front fender is not in great condition due to pitting.  You can see the flawed condition of the rear fender above.     

Now the question is do I go semi-cafe or try to make her look like a stock 1976 in great shape?  If I go cafe I will paint the fenders and powdercoat the rims black, solving my chrome problem.  If I go stockish I will need to drop more coin.

[fendersrule]

I prefer to prime and undercoat the fenders.

I also prefer to prime and paint the inside of the tail light holder. Water consistently and constantly gets trapped in there.

[Juan1]

Thanks for the tip!  Attached are before and after pictures of the headlight area you are describing.  I was able to get much of the rust off, but some remained.

Some of my frustration has abated after picking up some '76 rims on ebay for relatively cheap.  If they look as good as they did in the ebay listing I'll use them.  If not I will relist them. 

[Juan1]

I have replaced the valve seals and will be replacing the engine studs, gaskets, beat-up cam chain tensioner, and rings.  In the mean time I have been cleaning up the engine in preperation for painting it Duplicolor Aluminum.

[Juan1]

I should also mention that I had my fenders rechromed.  The price was south of $250, and if anything the parts look too new.  If anyone needs a chrome guy in the San Diego area I highly recommend Sanchez Polishing in Escondido.