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  1. #1
    CB750 Enthusiast pidjones's Avatar
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    The Rocket, or pidjones winter of 18-19 rat bike project

    Here she is, picked up today. A 1979 CB750F SuperSport. The GL1000 that I last rescued will have to move to the next room for a while I guess. Had to remove the calipers and pull the bake pads out to get the wheels freed up to load/unload it. Before I took it in the shop (basement garage) the tank came off and was drained of the stinky stale gas. The I left the tank outside because it still stinks. The last time this was tagged was 1999! It actually seems to be in pretty good shape other than cosmetics. Because of that, I plan to make it a rat bike by getting it to run safely and well but not fixing appearance items. The PO had the front part of the seat cut down, but it seems to be in good shape. I'll start pulling calipers and working them while I let some oil soak in the cylinders (couldn't do that very well on the GoldWing). There is very little rust compared to my GL1000, and the electrics at least appear to be in good shape with only one splice for a broken wire (that broke again). Intact airbox with a clean filter in it along with a few hickory nut shells and leaves. A LOT of mold/green crud but that won't get cleaned off unless in has to for performance sake. If anyone can identify these air forks, I'd appreciate it as I know they aren't correct for this bike and they are presently soft as can be.
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  2. #2
    CB750 Enthusiast pidjones's Avatar
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    Pulled the stator today. Inside of the case was full of aluminum oxide powder. Small hole in the bottom of the cover from a slide. Still needs more cleaning, but the stator ohms out good as do the field coils. The slip rings look pretty bad and I may pull the field rotor to chuck in the lathe and dress the slip rings. I got the cam cover off (non-standard bolts on the outside corners) and smeared assembly lube on all of the cam lobes, then squirted oil at the cam bearings and chains. Some bright "mechanic" shoved a sheet metal screw in to hold the tach cable, and cracked that tower. I think that it can be patched up with JB, and a standard 5mm fine still screws down into it. Plugs out 1st thing this morning, and PBBlaster squirted in. That set until this afternoon, and I bared the crank over. A little scratchy sounding at first. Smoothed out nice after a couple turns. Put motor oil down each hole and will roll it again tomorrow. P.O. claimed to have replaced the reg-rec. I really like this charging system better than the GL1000, which has an alt that puts out 100% and the reg/rec shorts excess to ground.
    "Love 'em all.... Let GOD sort 'em out!"

  3. #3
    CB750 Enthusiast pidjones's Avatar
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    Don't have the tool to pull the rotor from the crankshaft and clean behind it/chuck it and polish the slip rings on the lathe. Don't have the steel to make one right now either (I probably will, later). So, went from 220 through 2000 grit cleaning corrosion and polishing the rings. Ohmed out the stator (.4 ohms each leg, 4.6 meg to ground) and rotor (4.4 ohms). I don't know where the mild continuity to ground on the stator is from. I cleaned it pretty well, even stuck it in the sink for scrubbing and after blowing it out with the compressor, baked it a little with the heat gun. There has been a lot of water in there. There was a poorly patched hole in the bottom of the stator cover from an accident. I dug their JB Weld out and replaced it with my own. I'll need to replace a lot of screws for the covers (Ace is the place). Next is to set valves and then check out the electrics, change the oil, and check compression.
    "Love 'em all.... Let GOD sort 'em out!"

  4. #4
    CB750 Enthusiast pidjones's Avatar
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    Shazbot! Measured valve clearances. They range from 0 to 12 thousandths, with four at .0025 and two at .006. I've ordered the Motion Pro tool so the shims can be plucked, measured, and new ones ordered where I can't swap. Oh well, gives me time to go through the wiring, I guess.
    --------1-------------2--------------3-----------4
    E .0025/.0025----.004/.006------.006/.012---.004/.0025
    I .0025/.004----<.0015/.003----.004/.0045--.004/.003
    (all in inches)
    Last edited by pidjones; 09-17-2018 at 11:28 AM.
    "Love 'em all.... Let GOD sort 'em out!"

  5. #5
    CB750 Enthusiast pidjones's Avatar
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    New fun!

    Pulled the front calipers off today and they are headed to the bin. Both pistons frozen SOLID (can't turn with good large channel locks). These look to be CB750F calipers on home-made adapters to the C forks. SO, why not replace with C calipers and dual pistons? Found a pair on ebay already and he will combine shipping.
    Have the headlight apart and all of the connectors separated. Don't look as bad as the Hunley did, and most are the newer, smaller connections. I'll clean all of them, clean up the handle switches, clean the ignition switch, and splice the main power wire that had a broken crappy spice near the headstock. I don't really mind working on the electrics.
    I hate brakes. At least I didn't get brake fluid everywhere, because the system was BONE DRY! All that came out was rust dust. Already have a Chinabay master and I plan to clean the splitter and buy new lines.
    "Love 'em all.... Let GOD sort 'em out!"

  6. #6
    CB750 Enthusiast pidjones's Avatar
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    Today the battery got its acid and charge. Reworked the remaining electrical connections, repaired a burnt out fuse position (#1), installed a bypass fuse holder to replace the 30 Amp dogbone. The shim removal tool came in this afternoon, so I was able to pull and measure them all and will work out swap/purchases tomorrow. Last thing was to hook up the battery and a quick test of lights on the dash and tail light with key on, and bump the starter. Tomorrow I hope to get as far as a preliminary compression test. I know clearances are off, but it should reveal major (VERY low compression) issues.
    "Love 'em all.... Let GOD sort 'em out!"

  7. #7
    CB750 Enthusiast pidjones's Avatar
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    Shims on order, oil and filter changed (photo to come), and initial compression test done. MUCH better than I had feared. Was afraid there would be some ~20 psi or even Zero. Lowest dry was 90 psi, but they all went to over 150 with a squirt of oil, which has me hopeful for rings needing loosened up. Pretty amazing considering the spread in valve clearances. Starter cranked happily with no refurb needed. The outboard valve cover bolts had been swapped for standard bolts, so new ones are on order and the inboard bolts all now have new gaskets. BTW, in case it is new to anyone, the trick to getting new gaskets on the bolts undamaged is to soak them in HOT water for about five minutes, then the bolts pop right through them.

    .
    And here is the promised photo. Anybody? Bueller?Click image for larger version. 

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    Last edited by pidjones; 09-19-2018 at 05:05 PM.
    "Love 'em all.... Let GOD sort 'em out!"

  8. #8
    CB750 Enthusiast pidjones's Avatar
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    Positive (I think) progress this morning. Got the over-tight head bearing preload nut off, and after pulling the stem was able to remove the races from the headstock fairly easily. Helps the I had the tool fromremoving the Hunley's races on hand.* It looks like someone had grabbed the stem where it goes through the upper triple with vice grips or a pipe wrench, leaving heavy ridges that scared up the inside of tbe upper triple. I've become pretty good at removing such damage with a single cut mill file, so that is all Ok now. The axle spacer that fis in the right seal was badly pitted. I chucked it in the lathe and took a light cut. If it turns out too small when the new seal comes in, I'll chuck it in the bin and get a new one. Or make one if necessary. Tonight or tomorrow I'll cut the lower bearing off of the stem. This was easy on the GL1000 using a Dremmel and cutting wheel. Hopefully the same here. I kept inner and outer races from yhe GL1000 to use as drivers for installation.

    Have settled on the forks being from a Kawasaki KZ750H LTD (probably ~1980). Seals on order.
    "Love 'em all.... Let GOD sort 'em out!"

  9. #9
    CB750 Enthusiast pidjones's Avatar
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    Think I found why they had messed with forks and added a stabilizer. Probably chasing a steering wobble that was in fact caused by the lower stem bearing inner race being seriously damaged. But, that is hard to get off (actually a 10 minute job with a Dremmel), so they did all of this other stuff. At least, that is what I'm hoping. New bearings should be in this week. The outer race looks fine.


    Last edited by pidjones; 09-27-2018 at 10:24 AM.
    "Love 'em all.... Let GOD sort 'em out!"

  10. #10
    CB750 Enthusiast pidjones's Avatar
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    All attempts to save a piston for the one remaining caliper that I need have failed - they were all deeply pitted too much to rescue (finally got them out with the grease gun). So, one is on order and that caliper is cleaned and ready for it. Fork seals came in yesterday, so I installed them in the already-cleaned forks and mounted them up, Also installed a new "GP Touring" handlebar in black. It is very similar to the Euro bar I put on the Hunley, but a tad narrower as I've had problems maneuvering the Hunley in our tight basement.


    Today I pulled the carbs (used heat gun to soften the boots). Only did a cursory disassembly by removing a couple float bowls and a couple vacuum domes. Not as good as I'd hoped, but not nearly as bad as I had feared. Fairly sure this bike was last fueled prior to alcohol mandates as rust and varnish is all that I am seeing in the bowls. That varnish however has glued the needles to their seats, so the vacuum piston will not raise. I can rattle it a bit and even move it up and down ~ 1/2 mm, but the needle won't budge. Plans is soaking in carb cleaner to soften and dissolve the varnish so that they release without damage.
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    "Love 'em all.... Let GOD sort 'em out!"

  11. #11
    CB750 Enthusiast pidjones's Avatar
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    Today I was able to make a little more progress on the carbs. One at a time pulled the float bowl off each (no ruined screws!) and sprayed the bowls with carb cleaner, pulled the drain valves and opened overflow and drain on each, cleaned the valves. Pulled secondary main jet on each (each one plugged solid with lacquer) and softened the lacquer with carb cleaner then was able to work a .008" guitar string through and finally shoot cleaner through them. Loosened the needles with carb cleaner and gently, padded with rag and tongue depressor, pried each piston up to free the needles fully. Pretty gummy, but still a LOT easier than working through the damage caused by ethanol gas.

    Looks like the accelerator pump diaphragm will need replaced, however. Just so stiff that it hangs up when pressed. I'm sure all rubber will need replaced also, and already have bowl o-rings and rubber plugs on order. Should have the other o-rings in my supplies.

    Probably at a holding point for now. Tomorrow we are showing the GL1000 at a nearby street fair, and next week we go to Barber for the museum and vintage fest.
    Last edited by pidjones; 10-12-2018 at 09:52 PM.
    "Love 'em all.... Let GOD sort 'em out!"

  12. #12
    CB750 Enthusiast pidjones's Avatar
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    Afraid I'll need to replace the entire front end on this pig. Used a geometry calculator and see that trail with uncompressed forks is only ~3.1", and at full compression is ~2.3". No wonder a steering damper had been tacked on! This is all caused by the d@mned leading-axle forks. I'm sure that if I tighten the upper clamps back on 35mm forks they will crack, so I may look for a GL1000 front or original '79-'81 CB750F. Shazbot!
    "Love 'em all.... Let GOD sort 'em out!"

  13. #13
    CB750 Enthusiast pidjones's Avatar
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    Remembered that I have a set of '78 GL1000 forks in the garage left from the Hunley project. The tubes are pitted in the upper area, but not in the seal area (well, a stone ding, but it will smooth out enough). They were too rough looking for a show bike, but should be just the ticket for the rat bike 750. I'll need to pick up a triple set and probably new head bearings (again - unless I can tap the new ones I had installed on the 750 stem back off). Then the fun of figuring out how to mount the instruments (which surprisingly seem to work Ok). I have a set of GL1000 headlight ears in a storage crate that I took out to the shed last month, so I'll have to bring that back in. They are real rusty, so should match up well!

    All of this will have to wait until after Barber, however. After church the wife and I donned gear and I hooked up the Uni-go to the GL1800 for a test ride to one of our favorite restaurants. Loaded a box of books in the trailer to simulate luggage and it tracked beautifully over twisty roads there and interstate back. This was our first ride two-up with the single-wheel trailer and I think it will be great to haul to Birmingham. This is also kind of a test for us to make multi-week trips in the near future. I like that the Uni-go can be unhooked from the bike and rolled into hotel rooms as our luggage, convenient and eliminating the issue of security for an unhooked trailer left in the parking lot.
    "Love 'em all.... Let GOD sort 'em out!"

  14. #14
    CB750 Enthusiast pidjones's Avatar
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    Getting the forks together finally. Had to turn a cap for one because the original has disappeared. They are cleaned and assembled with new seals, waiting for new dust seals for filling and installation.

    The carbs are now broken down individually and #1 is fully cleaned, new o-rings installed, and reassembled. The floats on all of them were way off - probably trying to fix leaky float valves - I'm relapping the seats with jewelers rouge.

    The tank is flopping around all over with about 1.5 gallons of Evapo-rust in it. I think it will be fine, as this is all that my paint filter caught after draining a gallon of acetone that had been left in it for a couple weeks to get the varnish out.
    "Love 'em all.... Let GOD sort 'em out!"

  15. #15
    CB750 Enthusiast pidjones's Avatar
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    Fork dust seals came today as well as some nifty-looking red brake lines from China. Front forks are mounted with 200 cc each ATF. Now with them on, I see that I'll need a GL1000 front axle. Ebay!
    "Love 'em all.... Let GOD sort 'em out!"

  16. #16
    CB750 Enthusiast pidjones's Avatar
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    Finished cleaning, assembling, adjusting and testing through #3 carb tonight. Have to change out the acetone that I run the jets and such through in the US tank because it was getting too contaminated with varnish! Presently just pressure testing the float seats to see if they will hold ~2 psi for hours. Had to make a tool for lapping the seats as some were pretty dinged. Easy to pressure check while cleaning the next carb. I'll check them all with isopropyl before ganging them back together. Had to make the little washers on the pilot screw o-ring as they were all missing. Also bypassing all of the air cuts. Setting pilots 1/2 turn more open to accomodate. New accelerator pump is on order. This one is too stiff and often hangs up
    "Love 'em all.... Let GOD sort 'em out!"

  17. #17
    CB750 Enthusiast pidjones's Avatar
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    One thing the pressure test doesn't tell you is if your overflow tubes are cracked! Dooo. #2 and #4 both cracked. So, solder? JBWeld? How about - is heat shrink tubing gasoline proof? Let's find out! At least all of my float valves are seating well. But, I had to make a drain screw for #4 because it was too far corroded to clean up. Made one out of a bolt. Didn't worry about a screwdriver slot or an o-ring groove. This IS a rat bike!
    "Love 'em all.... Let GOD sort 'em out!"

  18. #18
    Moderator dirtdigger's Avatar
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    You could try soldering the tubes but just as easy to find used bowls on ebay, heat shrink definitey not fuel proof. I would give soldering a go, just be sure not to fill the tube, if the needle doesnt shut off it will fill your engine with fuel if the overflow isnt free and open.

  19. #19
    CB750 Enthusiast pidjones's Avatar
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    Filling the tube is not a concern - it can always be drilled out. I've already ebayed more than I wanted on this bike, and haven't even gotten to the drive, rear shocks, rear wheel bearings, rear brakes yet. I'll try the solder.
    "Love 'em all.... Let GOD sort 'em out!"

  20. #20
    CB750 Enthusiast pidjones's Avatar
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    The heat shrink hot glue liner had already softened in the remaining bit of isopropyl in the carbs, so I cut it off with a razor blade, wiped the glue off with carb cleaner, scraped the crack with an Xacto blade, fluxed and soldered it up. With the powerful butane iron I have, was able to get a good flow until down near the bottom where the aluminum sucked the heat out. Hold the isopropyl well, so the carbs are finished except for the accelerator pump rebuild kit that is on a slow boat from Taiwan.

    Chain is off and in the trash - too rusted to consider. Front wheel bearings are rusted solid, but I have replacements. Made a tool to remove the bearing nut and it worked well.

    Tank is now de-rusted, flushed with pressure washer, dried, and sprayed with fogging oil. Pulled a ~1/2" thick chunk of Bondo off of it and think I'll try the inner tube trick to pop some of that big dent back out (will give more fuel space if nothing else).
    Attached Thumbnails Attached Thumbnails repair2.jpg  
    "Love 'em all.... Let GOD sort 'em out!"

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