Survivor Chop: Repairs and upgrades everywhere

 

After a weekend trip to Gettysburg with a couple friends, I found a few things on this bike that could use some love.  On top of that, some of the equipment is just old and could use replacement so I don't have to deal with issues roadside.  This includes some electrical repairs, exhaust repairs, new oil and vent lines, new wheel bearings, new front rotor, and a tighter rear suspension. 

The last one in the list above was a bit of a surprise to me after I loaded the bike up with my gear for the weekend.  I went over a bridge and heard a screeching sound like the wheel locking up.  It turns out that the rear wheel was rubbing the fender... a lot.  To remedy this, I asked John to whip up some spacers out of scrap to preload the rear springs a bit more. I measured the spring rate to be about 185 lbs/in, so we went with 1/4" spacers to add about 90 lbs more preload (46.25 lbs on each side).  This helped quite a bit, but it still rubs slightly over heavy bumps.

I slapped some black paint on the underside of the fender to cover the raw metal from the tire rubbing over the years.  This also gives the tire a fresh canvas to scuff up later.  Overall, the bike rides about the same, but the tire scuffing is only slight.  John made up a second set of spacers to add which are 1/8".  I may add those and see if I can avoid tire contact with the fender altogether.

I hope to use this bike as my touring ride for a long time to come.  With that in mind, I want it to be as reliable as possible.  And while the original regulator and rectifier on the CB750's is quite reliable, it is already 49 years old.  So out with the old and in with the new.  A new regulator rectifier combo from Rick's Motorsports (model 27-10100).  This reg/rect combo is plug and play with the factory wiring harness, which surprisingly, this chop has.  Removing the old parts and installing the new combo unit was a huge pain only because the main wiring fixture from the original CB750 was mounted under the oil tank, making it impossible to remove the original regulator and rectifier without removing the rear fender.  This was one big reason why I did this upgrade. I would not have been able to replace the original parts roadside.

I also replaced the glass tube fuse holder with a more modern blade type fuse.  While this bike retains the factory harness, someone consolidated the fuses to just a single 20 amp fuse.  I would prefer separate fuses, but I've owned and built many bikes with just one main fuse without any trouble.

The exhaust repairs included replacing the no. 10 bolts on the exhaust sleeves at the tube joint near the footpegs with 1/4-20 bolts.  The right side exhaust came loose while up in Gettysburg and I had to use bailing wire to strap it to the frame.  I don't like the fact that the sleeves are a tad small and simply black pipe, but they will work for now. I also sealed some leaks at the spigots with aluminum borrowed from an Arizona Green Tea can.  Nothing but the finest material.

The new oil and vent lines were brought to you by Home Depot.  Reinforced clear vinyl tube for the oil lines and clear non-reinforced vinyl tube for the vent lines.  I like that the oil flow is visible.  This material gets soft as the are heated, so be sure to use reinforced tube for the oil lines.  

I have run many bikes on the original wheel bearings for years without noticing any issues, until I actually replaced a full set on a bike.  The ride was significantly smoother and handling in corners was notably better.  The bearings on this bike had their time in the spotlight and exhibited some rough spots. And while I would have just run these in the past (and did for a while this past year), bearings are cheap, replacing them is good insurance, and the difference is quite noticeable.  

The bearings for the hallcraft front hub were conversion bearings to adapt the wheel to the 5/8" axle.  The part number from NSK is 6203-625VVC3.  Simply drive the old ones out carefully with a punch, clean all the surfaces, inspect the inner sleeve for damage, and install the new bearings.  Be sure not to compress the bearings in so tight that they bind from compressing the inner sleeve.  Press the bearings in until the inner sleeve is in contact with the inner race of each bearing, but both bearings spin easily.  This goes for the rear hub too.

While doing the bearings, I cleaned and polished everything along the way.  It's easy to get to those small spots now, and not so much later.  

The rear wheel has three bearings, two in the hub, and one in the sprocket carrier.  All Balls sells a great kit that I have used many times.  The part number is 25-1362 for the CB750 rear wheel.  It comes with all three bearings and a new shaft seal for the sprocket carrier.  This shaft seal was important for the factory bearings, which were not sealed.  However, the All Balls kit comes with sealed bearings.  

The sprocket carrier has a bearing retainer on it.  When I cant find my retainer tool, I just use a set of hex keys or punches that are close to the diameter of the holes and rotate them with a pry bar.  To prevent the aluminum threads from galling, clean the retainer and spray the threads with penetrant.  Leave the sprocket carrier in the wheel while working on the retainer as it will help hold the piece steady.

Once the retainer is removed, drive the bearing out from the other side and remove the shaft seal.  Clean all the surfaces and install the new bearing and shaft seal.  When installing the new bearing, you can use the old bearing as an intermediate surface to bash on.  It's the same size as the new bearing and will distribute the force evenly. One other tip: If the shaft seal is being a pain to remove, heat the retainer with a torch and melt/soften the rubber shaft seal.  It will pull out easily.

The rear hub also has a bearing retainer and I use a similar method as above.  Instead of hex keys though, I use flathead screwdrivers to engage more of the surface of the retainer. Use penetrant to minimize/prevent thread galling.

Drive the bearings out from each side, clean, and replace.  Once again, the old bearings can be used to assist with seating the new bearings.  And once again, make sure to inspect the bearing sleeve that rests between the hub bearings and ensure that it is in contact with the inner races of the bearings and the bearings spin freely.  Reinstall the bearing retainer and you're all done.  This is also a good time to inspect your kush drive rubbers, your rear brake shoes, and your brake liner.  Ohh and clean/polish everything!  One more pro tip:  Matching the bearing seal color to the bike adds 20 horsepower at the wheel. Luckily, the All Balls kit is blue!

Last on the list for this post is the front rotor. The original one was heavily pitted.  They were made by Hurst-Airheart, now known as Airheart Brakes.  You can purchase a rotor that's similar in dimension, but will need some modification to mount to the Hallcraft hub.  The part number for this replacement is 3301-1003 (7.75" diameter, 0.119" thickness, 3.50" bolt circle diameter, 0.194" bolt hole diameter).  The bolt holes need to be counter-sinked and opened up to accept the 1/4-28 bolts that the Hallcraft hub uses.

I didn't purchase a new one and go down the route of modifying it to work because I had a few of these rotors sitting around.  I checked the potential replacement for warping, pitting, and thickness.  Then cleaned, sanded, and painted it to make it look purdy.  I installed with the original bolts because they were in good shape and used blue loctite.

So that wraps up a good bit of work to get this bike, that my friends have named "Blue Waffle", in top shape.  Better electrics, newer bearings, fresher brakes, new lines, tighter suspension.  After this, I'm going to spend some time tweaking the tuning a bit.  I feel that there's plenty of room to improve this bike's performance and reliability.  So next we'll take a look back at the carburetors and the ignition.

Freshening up a Survivor CB750 Chop

1972 CB750 survivor chop headed to the shop for some work

                             

   

After buzzing around on the CB550 for a while, I decided to make a deal with John at DCW and traded it for a survivor chop that he picked up a while ago.  I'm glad the 550 will still be around.  The kids loved working on it and we have plenty of good memories with it in the family.  But, onto new things. Adios, good buddy.

Uncle Mike's restored 1978 CB550 headed over to John's

Imaginary road trip to Arizona to visit their cousin

The bike under the microscope is a 1972 CB750 in a trailing plunger frame, equipped with a springer, mini disc, spoke wheels, 6 bend bars, factory wiring, factory controls, factory turn signals, and a bunch of other factory bits.  It was a quality build from the 70's that must have used a kit that swaps over a lot of the factory items.  The factory light cluster is even mounted between the custom risers that John made to fit the narrow 6 bends to the springer riser spacing.  My plan is to retain all of the factory items, clean the bike up, and do a few upgrades for safety and reliability.

Factory indicator dash and wiring repair in progress

The frame is conservatively molded, with a great layered paint job.  It needed a good bath, some fresh paint on the engine, a little wiring, and a few mechanical fixes.  Otherwise, it's in great shape for being nearly 50 years old.  The first thing I took care of was the bath.  It was covered in a nice layer of road grime and dust. What looked like bad chrome was really just aged chrome with a lot of dirt.  

After it was relatively clean, I fixed the wiring in the cluster that the owner John bought it from had modified.  This gentleman decided to extend the wires for the for the factory controls so he could fit some apes.  The apes didn't look right and were the first thing to go when John got the bike.  I finished properly crimping and extending the wiring, then added a fiber loom to keep it organized and tidy.  I had to rebuild a set of control housings and buttons from a couple sets because the original ones were worn out. I cut out a hole for the wiring to exit the throttle housing on the front, close to the brake perch, because the bars were not dimpled like factory bars.  The picture of the factory light cluster above shows the new looms, cables, and factory controls midway through the process of wiring.

While working on gathering a few parts, I've begun stripping items off the engine to fix the peeling top end paint.  At some point, someone painted the top end black, but seemed to have skipped surface prep altogether.  The carbs were pulled and will be cleaned/inspected and new fuel lines will be routed. The exhaust and brackets will be cleaned and the hardware will be upgraded for a tighter fit.  The long pipes have a joint just behind the mid controls that is slugged with a piece of black pipe.  It fits nicely, but the small #10 hardware allows for a little more movement in the kickup section of the pipes than I like.  No one likes to see floppy pipes on someone's bike when you're trailing behind them... just waiting for them to pop off and find their way under your tire.

Black pipe inserts for 4-4 exhaust kickups

On the first trip around the neighborhood to give the kids a little ride, I noticed that the clutch was dragging quite a bit.  With the engine off, in first gear, clutch in, rolling the bike would spin the engine.  It certainly needed an oil change, but since I'm replacing the crusty chromed covers with polished aluminum ones, I decided to inspect the clutch.  Upon disassembly, I found 2 of the 4 pressure plate bolts were snapped off and only being held in by some mysterious material, possibly galvanic corrosion.  The clutch fibers, steels, springs, and basket were in great shape.  Perhaps a little flex in the pressure plate along with a very sticky motor oil was causing the drag.  At this point I'll be installing a new clutch plate because 2 of the posts are filled with steel studs and the other two are likely damaged because the bolts were significantly over-torqued.  While the clutch center is out, I'll add "V" grooves to the oiling holes to increase film capture and aide with oiling the clutch (a la Hondaman).

Grungy engine and dis-assembled clutch

Clutch plate with damaged posts

This is a long intro for the new addition.  Eventually we might come up with some ridiculous name for the bike instead of "the blue bike," so it can join the ranks of Rock Flute, Bat Vagina, and War Bagel. Usually only the bikes that hang around for a while get a name.  I expect to hang onto this one for a long time.

To Do:

- Clutch: Finish repairing the clutch, scuff the steels, V groove the clutch center, properly torque pressure plate bolts to 6-7.5 ft. lbs and the clutch nut to 33-36 ft lbs.

- Dress Engine: Prep and repaint the top end to factory aluminum, install new polished covers.

- Brakes: Source front brake lines and fit new radial master cylinder (slim fit with the 6 bends), replace caliper stay.

- Exhaust: Upgrade hardware on exhaust pipes and add spacers to rear bracket to raise exhaust 1/2".

- Chain Guard: Replace or clean and properly secure.

- Speedo/Tach Install: Add mini speedo and tach with custom drive cables (factory speedo drive).

- General Maintenance: Clean/inspect/sync/document carbs, set valve clearance, timing, cam chain tension, oil change. 

- General bike inspection: Put a wrench on everything, check brakes, check lighting, check tires/wheels, check fuses, check all soft and hard components, etc.

- General upgrades and repairs: Weld wider plate to kickstand and a bunch of unknowns.

- Clean and Polish: shine paint and metals, treat soft components, restore rubber/plastic coloring.  Buffing wheel, polishing compounds, silicone treatments, rubber softener, etc.

- Bunch of other little things:  All those things I cant think of right now.