1974 CB550 KO Restoration Project

Discussion in 'Old's Cool' started by tom c, Aug 14, 2019.

  1. KeithTurk

    KeithTurk Been here awhile

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    The box and bags make the bike useable... one of mine is set up that way and when all four of them are sitting there, it's the one I migrate to... thing can bring home 5 cases of Coke!!!
  2. Saber55

    Saber55 Adventurer Supporter

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    I have a question for you guys. I have read through the threads and I love the bikes that have been restored. I recently began a restoration on a 1971 CB350. Where is the best place to acquire the Honda parts?
  3. tom c

    tom c Teflon Tommy Supporter

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    some that I’ve used:

    4into1.com
    davidsilverspares.com
    partzilla.com
    eBay
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  4. ADVDucs33

    ADVDucs33 Been here awhile

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    All the above are great. However, I have one rather huge one to add the the list since you are in Ohio....

    Mid Ohio Vintage Motorcycle Days.
    https://americanmotorcyclist.com/2020-ama-vintage-motorcycle-days-will-be-july-10-12/

    Words can't describe the amazing. Parts will be much, much cheaper then anything you find online. From David Silver's products being sold by the man himself right there, to a $50 cb350 parts bike- you'll find what you need to make it perfect.


    (I've been attending every year for the last 8 years in a row)
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  5. Saber55

    Saber55 Adventurer Supporter

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    Awesome! Thank you for letting me know. You come all the way out here from NV?
  6. ADVDucs33

    ADVDucs33 Been here awhile

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    Its a trip I'd do on foot with crutches if I had to.
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  7. tom c

    tom c Teflon Tommy Supporter

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    Well it's been quite some time since my last update on the 550. I decided to finish up the restoration of my 69 Honda CB90:

    That little project was completed just in time to put her on the market just as coronavirus hit. Bad timing but I guess I can hold onto her for little while before she gets sold eventually.

    Well once the CT90 was finished attention was turned to the CB550 - here she is, now tagged and street legal:
    [​IMG]

    I can't disagree with those of you who commented on how the huge luggage rack and top box are not complimentary to the lines of this bike. For now they are off the bike. I would like to take some trips on this one, and when I do so I can put them back on along with the period side boxes that Goosecreek is painting - along with repainting the left side cover, which fell off the other day on a test ride around the block (totally my fault).

    Now that she's tagged I was able to take her out for a high speed ride which was a learning experience. The butcher job done by previous owners on the original exhaust pipes made them LOUD, way too loud for my liking, so I had to do something about that.

    Here's the before picture:
    [​IMG]
    I'm not sure why the ends of the top pipes were totally cut off but the bottoms only had the four holes drilled through the ends...

    I fashioned 2 1/2" discs out of 16ga steel and cut a 1" hole in the middle:
    [​IMG]

    These fit well enough into the muffler ends:
    [​IMG]

    To fix them in place temporarily before I have them tack welded into place more permanently I drilled some holes in the "inner" exhaust pipe and used a cotter pin to hold them in place thusly:
    [​IMG]
    I also used some high temp sealant around the edges to seal things up. It's a temporary fix, good enough for me to confirm that this solution will reduce the noise sufficiently. Once we are out of quarantine I'll ask Wayne to weld them up.

    So far my high temp JB Weld patch of the holes between header and muffler has held up, but it is still early times on that fix:
    [​IMG] [​IMG]
    Others in the SOHC/4 forum have tried and failed with this technique.
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  8. tom c

    tom c Teflon Tommy Supporter

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    My initial plan was to have a bunch of top end work done to the 550 this winter but there were too many other projects in the garage for me to get around to it, so I decided to ride the bike with the motor as is for this season, then get the top end work done next winter. Let's get her into riding condition and put some miles on her before that project begins.

    Still there is lots to do to the 550. Parts began to arrive:
    [​IMG]

    The parts to the right are for Goosecreek's 1986 Honda Fourtrax 250, most of the other bits are for the 550. New cables, stainless steel brake lines, new caliper piston and seal, master cylinder rebuild, clutch, fuel line, valve tappet covers (some of the old ones were cracked), rear shocks/springs as well as fork springs.

    I noticed some clutch slippage at high throttle as well as some slow clutch engagement at times when upshifting, so new clutch and springs were ordered. I got the heavy duty spring set with 10% higher spring rate than OEM. That was a mistake, it's very hard to pull in the clutch now, so I have new OEM replacement springs on the way. Interestingly, there are 6 springs included in the EBC clutch spring set although the bike only requires 4 springs. I thought perhaps that I ordered the wrong set but after checking it is correct, in other bikes all 6 springs are used.

    (note to self - next time be sure to put on the oil drain plug before filling the crankcase with oil)

    I tackled the front brake work next, which went smoothly for the most part. It did take a very long time for all the little air bubbles to work themselves out of the system. After lots and lots of bleeding it is necessary to pump the brake handle over and over to force the last bits of air out of the system. I read lots of posts on SOHC/4 about the right way to do this and I think I tried them all. But in the end it just took an hour or so (at least it seemed that long) to coax the tiny air bubbles out of the system. On other bikes I've done this a big air bubble would be forced out after a few pumps. On this bike it was a seemingly endless stream of very tiny little bubbles. But in the end the brake lever firmed up and I've got front brakes. Not the greatest of brakes but I've read that Honda engineers of the day purposefully built that brake system to underperform because disc brakes were new to production motorcycles at the time and there was concern that too many folks unused to front disc brakes would grab too much brake up front and lose control. Maybe that's true, in any case I'm seriously considering adding a second disc up front. The right fork leg has the necessary mounting hardware and the rest of the brake hardware up front is designed so that it can be used on either side of the wheel. But that project is for the future.

    Suspension - I knew at the very least she needed springs - the bike hardly leaned over on the sidestand and it was a herculean effort to pull her up onto the center stand. I didn't want to spend an arm and a leg though, so after some internet searching I settled on Progressive Suspension brand components:

    Progressive Suspension 11-1106 fork springs ($60 - found a good ebay deal)
    Progressive Suspension 12-1204B 12 Series 13in. Shocks ($167)
    Progressive Suspension 03-1394C 12 Series Springs (70-120 psi) - Chrome ($82)

    The fork springs were noticeably longer than the old springs, so much so that it was difficult to re-install the fork cap bolt.
    [​IMG]
    The owners manual calls for 10-30, but I used Maxima 10W fork oil. Apparently there were no fork specific oils available back when these bikes were being build. The spec in the owners manual only gives an oil fill volumen, no spec on oil height in the fork tube. Per the instructions that came with the fork springs, I filled the fork tubes to a height of 140mm with springs out and forks fully compressed after cycling the forks up and down a few times to remove trapped air. I had already replaced the fork seals with All Balls Racing Motorcycle Fork & Dust Seal Kit 56-137.

    The spring rates on both front and back are slightly higher than OEM, hopefully appropriate for a fat old guy. The rear shocks fully extended length is 1/2" longer than stock. I was worried that might shift the fork geometry towards instability but so far that is not a problem. I haven't put enough miles on her to give a proper evaluation of the suspension mods, but I can tell you that now there is a good lean on the side stand and she rolls right up on the centerstand.
    [​IMG]

    Next on the to do list are new Avon AM 26 Roadmasters to replace the ancient Dunlops!
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  9. Joeboblglt

    Joeboblglt Adventurer

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    Thank you, Tom! I enjoyed the CT90 but this 550 build is great! I really appreciate you taking the time to share it with us.

    Joe
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  10. tom c

    tom c Teflon Tommy Supporter

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    Ah, where are we now on this project? Plenty of housebound quarantine time now to spend on the golden 550.

    Tires have arrived. Avon AM26 Roadriders.
    [​IMG]
    Lovely. Haven't had a change to try them out very much yet though with the Covid-19 travel restrictions imposed on us all.

    While I had the tires off the rims I retrued the wheels, centered the rear rim in the hub and adjusted the front wheel offset so that the both wheels are in the same track. According to the SOHC/4 forum gurus this can be an issue with these bikes. I moved the front wheel 7mm towards the disc brake side of the hub to get things in line. I should have taken pictures, it was quite the procedure. I hope that Hondaman doesn't mind me using this illustration from his book. It gives you the general picture.
    [​IMG]
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  11. tom c

    tom c Teflon Tommy Supporter

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    With the new tires installed I took her for a short ride to see how things were going, and there was something funny going on with the motor, a bit of roughness that just felt off. I had just installed new plugs so when I got her home I took them out for a look see:
    [​IMG]
    Something going on with cylinder #3. I had just been reading the section in Hondaman's CB750 book about ignition systems and coils. In these old bikes the 45 year old spark plug caps can fail and when they do so the resistance of one or more of them changes. Cylinders 1 and 4 share one coil, 2 and 3 the other. when the coil fires it sends energy to both of the spark plugs to which it is connected. If the plug caps are significantly different in resistance the spark energy delivered to each plug is different. DAMHIK, but the lower resistance path makes a poorer spark.

    So I checked the resistances of each cap and what do you know.....
    [​IMG]

    The plug caps for cylinders 1 & 4 are quite close in resistance. Cylinders 2 & 3 are quite different, with the lower resistance going to the dirty plug. So my working hypothesis is that this is what is causing the fouling of cylinder #3. In any case new plug caps have been ordered and while I was at it new ignition coils as well, all ordered from partsnmore.com. Coils are part number #17-6823, Sakura brand I am told. NGK 5KΩ.

    In the meantime I'll test my hypothesis by switching plug caps #2 and #3 and seeing if the fouling changes cylinders.

    On to the next problem!
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  12. tom c

    tom c Teflon Tommy Supporter

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    Next up on the list of things to do - camshaft!

    A few months ago I was lucky to find a brand new Megacycle #12601 performance cam for the 550 on ebay for $125 (normally $450 and you send them the old cam) The deal of the century! This cam has around the same lift as OEM, but more overlap and duration. I was going to wait until I had the top end rebuild before I installed it but I then decided that I wanted to ride her for a season before the rebuild, and since there is plenty of time for wrenching right now, what the heck? Let's put it in!

    Here's the old one coming out:
    [​IMG]
    hmmm. Not so many pictures of this installation. Too busy trying to keep from damaging my precious disposable gloves....

    I thought that I had done a good job of keeping the cam chain and gear properly indexed, but when I checked the manual I saw that she was one tooth off. I'm not sure if it was that way when I opened her up or perhaps the chain slipped a link on the crankshaft. In the end the correct indexing was achieved.
    [​IMG]

    She started right up and idled well afterwards but it was raining yesterday so no test ride yet. Definitely will go out today for a short test ride.

    Oh yeah, one more item checked off the list yesterday - After I replaced the clutch plates and springs with new EBC components which included 10% stiffer clutch springs I realized that I'm too old and weak for %10 stronger anything, so I bought four NOS OEM clutch springs and put them in last night.
    Here's a comparison of new springs:
    [​IMG]
    OEM spring on right, EBC 10% stiffer spring on left.

    As I was torquing the clutch bolts up - snap! One of the bolts broke!
    [​IMG]
    ... and yes, I was in fact using a torque wrench!

    [​IMG]
    Fortunately it was easy to unscrew the broken bit. I replaced all the old bolts with new ones.
    [​IMG]

    Those stainless steel bolts were what I had here in the garage, but there is no need for stainless in the clutch, so I'll probably replace them with some stronger grade of bolt. Perhaps not necessary?

    There is one more upgrade that I did a few weeks ago that perhaps I haven't yet mentioned - I added Hondaman's transistorized ignition module to the bike. This module takes over the triggering of the coils from the points. It still uses the points as the trigger signal, but the hard work is done by the transistors inside the unit, thereby saving the coils from having to do the work of moving lots of electrons so once set, the points will not wear significantly - set and forget! The can be purchased at www.SOHC4shop.com. I put this in a few weeks ago and it seems to work great! Takes alot of the quesswork (for me) out of the ignition system and is much cheaper than a full blown electronic ignition system.

    Anyway, once it warms up a bit today I'll take her for a short ride to see how this recent spate of work has done. Actually lots of things accomplished, including the following:

    • Suspension upgrades
    • New tires
    • Wheel tracks centered and aligned
    • Clutch
    • Performance cam
    I won't get the new coils and plug caps until Thursday, so in the meantime on the test ride I'll see if switching plug caps #2 and #3 moves the fouling problem from cylinder 3 to cylinder 2.
  13. tom c

    tom c Teflon Tommy Supporter

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    Well I only felt comfortable with a short ride what with the nonessential travel restrictions in place (with which I agree ), but the short ride was enough for me to like the way the motor feels with the new cam. Much more midrange pull. Very nice. There are a few more recommended mods to the 550 including some work to the inlet pipes between carb and head to remove rough casting marks and matching up the inlet pipe to the contour of the intake port. I decided it was a good time to get this work started and it is something that I can do myself. So off with the carbs and inlet pipes!
    [​IMG]
    The old hard rubber tubes will be replaced as they are known to be difficult to seal as they age.

    The inside of an intake tube here, before any work is done to smooth them out:
    [​IMG]
    I'll add a washer to the screw that's poking up into the flow stream. I can't show you a picture but I could feel the mismatch between the inlet tube and intake port when I stuck a finger down the inlet tube. It's dremel time.

    Before I pulled the carbs off I did a compression test of the motor with these results:
    [​IMG]
    They are within 10% of each other. I wish they were higher but it could be due to my compression tester.
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  14. Fearless

    Fearless Brutally Honest Supporter

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    Hey Tom, Old school trick to salvage hard, dried-out rubber parts:
    Soak them in Wintergreen oil or (as I use) the less expensive synthetic, Methyl Salicylate (available on eBay). Soak them overnight at 100°~125° . You'll be amazed....
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  15. tom c

    tom c Teflon Tommy Supporter

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    Worked on the intake tubes today:
    A7A7E280-B893-4145-9A35-3E0D45E90CB0.jpeg 0DFA601D-86E8-41B0-BD65-916790678B08.jpeg C62E9779-AA23-4E37-92B1-4804BD75D710.jpeg
    that’s probably good enough.

    celebrating with a fancy beer:

    Attached Files:

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  16. MacNoob

    MacNoob piney fresh

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    I like that orange! I have a '71 CL175 that's supposed to be "Candy Topaz Orange" - did you try to match that Honda colour, or go with the Corvette paint?
  17. tom c

    tom c Teflon Tommy Supporter

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    Went with Corvette Atomic Orange:
    [​IMG]
    [​IMG]
  18. tom c

    tom c Teflon Tommy Supporter

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    Reposed from the coronavirus jokes thread.....

    [​IMG]
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  19. tom c

    tom c Teflon Tommy Supporter

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    While I have the carbs off I changed the fuel line routing. It's important for these gravity fed carbs to keep the fuel lines always running downhill towards the carbs, otherwise trapped air bubbles can reduce fuel flow, more so as the tank empties and there is less head pressure. This was a problem on my CB350, it gave me lots of trouble until I figured it out. Use the right size fuel line cut to the correct length and route it properly. I'll try to get it right this time.

    Here's how I had the lines run - it worked but it wasn't correct:
    [​IMG]

    With the carbs off the bike it's easy to see the two holes in the carb manifold through which the fuel line is supposed to run:
    [​IMG]
    ...and that's 5.5mm ID fuel line from dratv.com

    I also have the new ignition coils installed:
    [​IMG]
    [​IMG]

    ...along with the new spark plug caps.

    Now waiting on an order from partzilla that includes new carb insulators. It's taking much more time than normal to get parts these days, blaming coronavirus.
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  20. tom c

    tom c Teflon Tommy Supporter

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    I finally got my Partzilla order, put the carbs back on her and went for short ride:
    [​IMG]
    down to the C&D canal, only legal dirt roads in Delaware. After a strong start the engine started to run a bit off with a loss in power, so back to the lift she went. I pulled the plugs and again saw the same old fouling of plug #3:
    [​IMG]
    Damn. I was confident that replacing the ignition coils/wires/caps would solve the problem. Wrong again!

    I re synched the carbs, but it did not seem that the #3 cylinder was off relative to the others.

    To eliminate other potential causes of #3 cylinder problem, I went back and checked the following:
    • compression test with engine warm @WOT - values within 10%
    • valve clearances - adjusted after cam was replaced
    • new o-rings on intake pipes
    • new rubber carb boots
    • carbs cleaned
    • carb float levels adjusted
    • carbs synched
    • Ignition timing and points dwell checked
    • spark plug gaps checked
    The factory setup of these bikes are such that the bikes tend to run rich. SOHC forum gurus recommend decreasing main jet size from 100 to 90 and installing one lower heat range spark plug. Stock plug is D7EA, currently installed, as are the stock #100 main jets. I have purchased a set of four #90 main jets but they have not yet been installed.

    One way to "fix" the problem might be to install a hotter plug in #3 cylinder, so I'd swap out the stock D7EA to a hotter D6EA.

    Maybe this funky behavior of one cylinder in these old SOHC/4 bikes is not so unusual and that the use of a hotter or colder plug to compensate for differences between cylinders is just par for the course. What do you guys think?

    In the meantime as I was replacing the stock cylinder head cover hex bolts and JIS screws with hex head bolts I jostled the key switch assembly and the electric switch part of the assembly popped off. I thought I could fix it but then I took a look at what the previous owner did when he "fixed" it:

    [​IMG][​IMG]

    ...what a mess. Not worth fixing. New ignition switch and seat lock set ordered from 4into1.com.
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