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'75 Honda CB400 Four revival

Finished her up

Excited to get the cylinder head back the next day, I spent the other evening out in the shop prepping and finishing up whatever other assembly I could do. With 35,000 miles on the clock I wanted to replace the cam chain, but did not want to split the crankcases to do it. But David Silver sells a rivet-type master link, allowing replacement by breaking the old chain and the new chain, then riveting back together. As it turns out the old chain showed less elongation than I had expected for the mileage, another testament to the value of the owner's frequent oil changes.

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I installed new countershaft and rear sprockets to go with the new chain on hand. The oil pump got tear down for inspection and all new O-rings since it was one of the major leaks.

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The ignition advance got disassembled, cleaned and lubed, and I installed and static timed new points.

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All cables got cleaned outside and lubed inside.

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Had to stop and pet the shop mascot, then stepped outside to watch the full moon behind fluffy clouds. Rain was forecast for the next day so that would make for a perfect shop day to install the head.

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My buddy brought the head over the next day, and after leak testing we installed the valves and torqued it down. Here the cam is in and we're ready to crank the starter to confirm oil pumping to the top end. Two steel tubes running parallel to the cam have small holes that squirt oil directly on each cam lobe. As well, the cam lobes dip into an oil bath with each revolution.

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Last thing for the day was bolting on the cylinder head cover and calling it a day.

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Next morning the coils went back on. The plug caps have been cleaned inside and out and a thin coat of dielectric grease applied to the insides and wire connections. Is it just me, or are cooling fins just a beautiful feature of air cooled engines?

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By the end of the day the bike was complete - valves and cam chain adjusted, carbs installed and synced, timing set, and that gorgeous exhaust system installed.

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Then of course it was test ride time! The bike is just an absolute joy to ride. It runs like a top and has rock solid handling and electric motor smoothness.

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A few more glamour shots:

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This has been a fun and very satisfying project. I will be doing a few shakedown rides and followup tuning before reluctantly handing the key back to my buddy, the bikes owner. Then we will be hitting the road for some nice rides, two old friends on our vintage bikes, just like the old days but for all the grey hair. Ride pics to follow.

-Bill
 
Absolutely beautiful! What a great job of restoration. Hats off!
 
Thanks everyone for the comments, so glad you enjoyed watching the process. Maybe I do get a bit compulsive, like when my wife walks through the shop and says, with an incredulous look on her face, "you're buffing washers??" But to me I'm just enjoying doing justice to the original designer's concept, and preserving some history. It's all fun.

-Bill
 
Thank you for buffing the washers.:thumbup

Enjoyed the build.
 
Many many thanks guys, so glad that present day moto heads can appreciate an old school bike like this. The cool thing for me is that I've encountered this exact bike many times over the past 41 years. First, I assembled it brand new out of the crate at the dealership where I worked, then instructed the (reckless) kid who bought it new, and did followup service. Then I repaired his first crash damage shortly after for the insurance company, then did the repair estimate after his second crash, upon which the insurer told the shop they were dropping the insured, so "make sure you estimate it as totaled" even though it had only superficial damage.

Then our shop sold it as-is to my buddy the present owner. I serviced it for him a couple of times, and replaced the head gasket to fix an oil leak a couple of years later, then I left the trade. But about 20 years later I did my friend a favor and fixed some wiring and carb problems on the bike. For the next 15 years or so I would see it sitting neglected in his front room, gathering dust and encrusted in oily grime. And now per this thread above I have been intimately re-connected with the bike by bringing it back to near-new condition. Sort of like re-setting the odometer on the bike, and soon my buddy and I will be going on rides together again, resetting our calendars to the old days.
-Bill
 
Finishing touches

One of the last parts of this project was rebuilding the leaky 40 year old Koni shocks. Koni still makes automotive shocks, but discontinued production of motorcycle shocks in 2000. They licensed rights to their cycle shocks to a new company in Australia named Ikon. San Francisco based Ikon Suspension USA can supply seals and other parts for later model Koni shocks, but the earlier models on this CB400F were different. Luckily I was able to get new seals from an independent Koni specialist, Robert Haag (rhaagusa [at] yahoo [dot] com), who has sourced parts that will work for these early style Koni shocks. Besides the leaky seals, the tiny orifices in the shocks were clogged with gunk, making the rebound dampening extremely stiff. So after thorough overhaul, the shocks are now working properly again.

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Besides the grime and corrosion of age, one of the major problems with this bike was its oil leaks - it had leaks from the rear shocks, front forks, brake master cylinder, and multiple engine leaks. So after replacing all gaskets and most seals and O-rings and test riding I was disheartened to see a bit of oil on the cylinder fins after the first couple of test rides. The problem turned out to be something I had never run into before, a couple of porous spots in the cylinder casting. These were very slight leaks and hard to pinpoint, but thanks to a tip from the excellent web site of Mike Nixon (http://www.motorcycleproject.com/) I was able to find and repair them. Mr. Nixon's tip was to clean the area, then spray on some aerosol athlete's foot dry spray powder, then run the bike and watch for the source of the leak. The spray goes on like white paint, allowing you to see any oil leak as a dark spot. Here is the cylinder after spraying:

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I took off on a test ride, stopping every mile or so to inspect. After about 2 miles I could see a couple of tiny dark spots between the fins. After 5 miles the spots looked bigger, but there was still no visible shiny oil. I continued to ride for about 15 miles, including several miles of 65 - 70 mph running. Back in the shop there was still no visible liquid oil on the fins, but the discolored area on the spray powder was bigger. Apparently the dry power was absorbing the oil which would have otherwise run out onto the fins. Here is how one of the leak sources looked after the extensive test ride. The arrow points to the leak, just a small discolored area:

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After applying epoxy and test riding the bike looks leak free now. I dropped the bike off to the owner, and we are planning a ride together this week. Thanks to Mike Nixon for the tip on finding oil leaks. They were such slight leaks it would have been impossible to pinpoint them otherwise.

-Bill
 
build threads like these are some of the most BA posts on teh barfs. so much fun to read through and so much knowledge/experience to soak up.

thanks for taking the time to do the rebuild and also for the extra time to share it with us, much appreciated!

enjoy the ride :ride
 
Wow, thank you so much for sharing. The finished product seems to be in "better than new" condition, especially when you consider it will likely now provide many miles of riding pleasure free from engine oil on the cooling fins :)
 
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