Topic: Hello from Northern MN: Repairing my CB550F

[MD]

Hello,

First solo drive of a motorbike was a Honda 50.  I would guess I was about 8 years old.  Previous to that I had sat in front of my grandfather or uncle on a CB350, and ran the throttle.  About 1988 I purchased my first and only street bike a 1975 Honda CB550F.  I was the third owner.  A previous owner put on a faring and installed a wider seat.  Due to money woes and needed repairs I last licensed the bike in 1992.  I have not had it running since 1993.  This June I pushed the bike out of the raspberry vines.  It had been under a tarp but that did not last 20 years.  Time to get it running.

First order of business was to get air in the tires.  (Three weeks later there is still air in the tires, good so far.)  After pushing 500 lbs. up a uneven slope and down across the yard.  I got it parked in the drive way.  I purchased an old fashion oil can and filled it with 10w30 oil, pulled each spark plug, and squirted 6 shots into each cylinder.  Two days later, I gave the kick starter a try.  The engine turned and I could feel the compression! 

With the engine not seized up, I removed the carburetors.   The carbs were seized up.  Break cleaner, Carb cleaner, and WD40 were used to free up the throttle valves.  Then it was on to cleaning the main jets which took a few days.  The next item was the floats and float valves.  All ports cleaned with carb cleaner squirting through I was feeling encouraged.  Ordered a new float, float valve and 4 new pins.  Those arrived today and I plan to install them tomorrow.

Today I drained the old oil and changed the filter.  If things go well I might try starting the bike tomorrow.

-MD

[calj737]

Welcome! Might want to throw in some new condensers and clean the points while you prepare for a re-fire.

[Stev-o]

Welcome.  The 550F is a fine bike, I'm bringing one back to life now too.

[MD]

Thanks for the greetings.  I'll be adding to this thread as a blog of my efforts to get the bike street worthy.

Things did not work out for starting the bike on Saturday.  Cleaned and remounted the float bowls.  One will require re-threading of the drain plug soon.  I could see no threads in the bowl.  The threads on the brass plug looked good.  I put a new o-ring on it after cleaning and added Teflon tape to the threads till I get a sleeve installed in the bowl. 

I thought I had a tee to hook up to the fuel lines.   No luck at the hardware store so I ordered one on Saturday.  The tank has had pin hole leaks for years.  I have added a 1/4" peacock to a 5 gallon plastic gas can that can be mounted on the luggage rack.  This will work for fuel  till I reline the fuel tank again.  I ordered a kit for doing that, battery and chain lube as well on Saturday.

Hooked up an old car battery, jumper cables, and a charger/booster to the bike.  Tested some of the electric functions.  Horn, turn sounder worked.  I thought I had the bike in neutral but I had to play with the clutch and shifter till the neutral like came on.  The starter worked and I was able to roll the engine over several times to start spreading the new oil.  The starter button is non stock.  The original switch stopped functioning after 1991 so I repaced the internals with micro switch I got from Radio Shack. 

-MD

[MD]

Time for an update.

Using the temporary tank I discovered a leaking drain plug on one carb bowl.   HARISULUV was able to sell me a replacement bowl.  Bought a new battery online only to discover that it did not come with electrolyte.  Stopped by a local parts store today and got it filled.  Replaced both throttle cables and the tachometer cable today. 

The bike does not have a stock seat.  Wobbly was able to identify it as a 77  Honda CB750 Automatic seat.  I have received a new cover for the seat.  Three modifications were made by a previous owner to mount the seat. 

1.  The seat side of the hinge was moved towards the center of the bike.
2.  The seat portion of the latch was moved towards the center of  the bike.
3.  The U shaped chrome tubing that sits above the rear fender was bent downwards to allow the seat to sit down.

The mod that causes the most pain is the location of the seat hinge.  The seat only opens to a 45 degree angle.  I plan on extending the bike half of the hinge outward and moving seat hinge outward as well to allow the seat to open 90 degrees.  Once the bike is running I will move on to putting on the new seat cover.

-MD

[Stev-o]

Why not get the proper seat?

[MD]

Why not get the proper seat?

The wider seat does feel better on longer rides. 

-MD

[MD]

With the new battery installed,  I tried starting the bike.  No bark at all.  Tried starter fluid still no bark.  Pulled the plugs and looked for spark.  No spark so I tried cleaning the points.  Had good spark from right outside cylinder.  When I pulled the left outside I found a broken spark plug.  Twisting out the top of the spark plug removed the resistor retaining screw.  It did not fall out.  New spark plugs are on the way.

-MD

[MD]

I decided to upgrade the ignition to solid state.  Dyna ignition and new coils as well.  The ignition was pretty straight forward except for me reversing the magnet.  With the old coils installed I was getting some strange behavior with the test light while setting the timing.  I think it is set but will test again.  Installing the new coils was hampered by not being able to get the impact driver directly above the front mounting screw.  Chewed the head up a bit but got it out.  When installing the new coils, the intact heads were installed in the front of the bike.  The right side coil went in easily.  The plug attachment post on the left side were hitting the electrical connection box.  I removed the box and its bracket to mount the left coil.  This week I'll figure out how to modify the bracket to get the box remounted.

-MD

[MD]

Reset the timing today.  Tried starting the engine, it barked a few times, added some throttle and the bike started for the first time in 22 years.    The exhaust was definitely smokey from the oil I squirted into the pistons. I have a leak between the muffler and the 4 to 1 pipes, still quieter than a Harley.   I replaced the regulator and rectifier.  I am beginning to see the light at the end of the tunnel.

-MD

[MD]

This week has been busy with work and a major honey do project.  I spent this afternoon pulling the carbs replaced two float valves and seats.  I also replaced a needle valve seat.  After getting the carbs reinstalled, I turned the gas on and I no longer have gas leaking out of the air intake so the basic cleaning of the carbs is done.  Reinstalling the air box and tubing, I discovered why some guys like switching to the carb mounted air filters.  They are much easier to work with.  Got the tubing reconnected and the air box remounted.  I replaced the stock air filter with a foam replacement.  New clutch cable got installed this week as well.  Next item will be the master cylinder rebuild.

-MD

[Ravie]

Where in northern mn? I'm originally from Grand Rapids area.

Sent from my LGLS740 using Tapatalk

[MD]

Where in northern mn? I'm originally from Grand Rapids area.

Sent from my LGLS740 using Tapatalk

Ravie,

I am in the Arrowhead region.

-MD

[MD]

Rebuilding the master cylinder has been proving to be a challenge.  I watched the videos on Common Motor Collective on how to dissemble and install the rebuild kit.    The piston was frozen and so was the retaining spring.  During my first efforts to remove it, I broke off one end of the spring.  After several days of trying and WD40, I got the spring off by filling the well with oil and repeatedly tugging at the one end left.  In the video they show using a punch to loosen up the piston.  After trying to tap it with a hammer,  I remembered that I have a press.  It easily moved the piston.  One word of caution, check the length of narrow section of the punch.  I had to clean the threads for the banjo with a tap, 10x1.25.  With the guts removed I cleaned the bore with 2200 grit paper.  I then polished the bore with cotton rags. 

Reassemble was far easier.  Getting the spring in was a little tricky since my snap pliers are for the outside clips.  With a super small set of channel-locs and a socket I was able to get the spring in place.  After getting it on the bike I had to bleed out some nasty looking brake fluid.  I pumped until all I was getting was new fluid.  I'll bleed the brakes again later this week. 

I really need to get that seat cover on now.

-MD

[MD]

Replacing the seat cover revealed a pan in much worse condition than anticipated.  I had to repair parts of the side of the pan with sheet metal.  If I had not bought the cover earlier this summer, I would have bought a whole replacement seat. 

Got the bike on the road today for the first time in over 20 years.  I did not want to run at highway speeds so I took a gravel road.  Kept the RPM's about 4000.  I could smell the years of dust coming off the pipes.  I started this project in June.  I still have more to do but it does feel good the get the bike moving again. 

Next step is the repairing of the gas tank.  So far I have been using a test tank made from a 2 1/2 gal. gas can.

-MD

[70CB750]

Congratulations!

[MD]

Congratulations!

Thank you,

Took her out for a 40 mile run today.  I have to get my body in shape for riding too.

-MD