The CB400F

Ever since I first laid eyes on one, the CB400F has been one of my “bucket list” bikes.  They are, in my opinion, the total package.  For a few short years, Honda was able to successfully blend aesthetics, engineering and performance in one small, economical two wheeled pleasure machine.    Light enough and small enough for shorter riders, but quick enough to please anyone and cross-country capable, the 400F really had everything one could ever want.

400F Advert

Dig the gear, man.

Tony had been thinking about upgrading from his first bike, a ’65 CB160, for months.  Tipping the scales at what I’d guess to be about 130lbs, friends were just about constantly forwarding Tony links to Craigslist ads for reasonably priced, mid-displacement bikes and had been for quite some time.  I honestly don’t remember who posted the CL ad for the yellow ’76 CB400F, but when I saw it, I suggested he call the guy and give it a look.  He asked if I’d come with him.  Of course.

The bike had been sitting, but supposedly ran fine when parked.  The fuel was drained, the airbox detached (but still in place), the dynamo cover scratched and the shift lever bent.  I saw a Dyna electronic ignition mounted on the bike’s right side.  The gas tank appeared to be in near perfect condition on the outside, with zero rust on the inside.  The side covers were in tact.  There was a ding in the #4 header pipe, but it was functional.  The bike was complete, but needed a battery, the carbs rebuilt and who knew what else.  The owner was firm on the price, but it was reasonable.  We made sure the motor wasn’t seized and Tony bought it – I basically talked him into it.

Getting acquainted...

After a month or so of sitting at Tony’s while he acquired the needed parts to get her back on the road, he brought it to my place on a Sunday.  Together, we pulled the carbs and got them disassembled before Tony had to head home.   Over the next day or two, I put the carbs back together and on the bike and yup – that bastard fired right up.  My excitement, however, was quickly extinguished by a rattle coming from the top end of the motor.   An attempt to tighten the cam chain tension using the factory method failed and I was starting to feel like I had talked Tony into buying a bike that needed a new cam chain – a job that requires a top end rebuild.

Keyster jets.....we'll see......

After a bit of research and some talking with a DTT member currently rebuilding a similar bike, I found that there are two methods to releasing a seized cam chain tensioner that don’t require a top end rebuild.  As the “Hail Mary” required pulling the valve cover, I went ahead and ordered one, and tried the first of the two.  This involves removing the 10mm blanking bolt from between the front motor mounts and inserting a punch or screwdriver into the hole until it hits the tensioner push rod.  After loosening the locknut and adjustment nut, one taps down on the punch, theoretically exerting pressure on the tensioner and tightening the chain.  Well, it didn’t work, and I burned the shit out of my hand in the process.

Two weeks later.....

Once the valve cover gasket arrived, I went ahead and dove in.  In retrospect, I’m glad this was the route taken, as it gave me the opportunity to give the cam, cam lobes, and rockers a good look, and they all appeared to have little to no wear.  Tapping on a long screwdriver inserted along side the cam chain and hitting the top of the “horse shoe” unit at the bottom of the tensioner gave almost immedialy and I knew that it had come free.  Relief, but I wasn’t out of the woods yet.  I buttoned everything back up and went to bed, as it was too late to run the bike with my kids sleeping.

The next night after work, I adjusted the valves and started the bike.  What a difference.  The motor was quieter, but not where I thought it should be.  After allowing it to warm up, I did the “blanking bolt” tightening procedure.  The RPMs dropped a bit and came back as the noise went away completely.  The engine was so much quieter I thought something was wrong, but throttle response was snappy and all four cylinders were firing.  I replaced the blanking bolt, tightened up the adjustment and locknuts and took the bike for a spin around the block.  Some popping alerted me to a hole in the muffler, but other than that the bike ran great.  Lots of pep for being a 400, smooth as silk and the engine sounded great.  A post-ride check of the spark plugs shows that things are looking good thus far.

Tony came and picked up the bike yesterday.  Having not started the bike all day, I set the choke, and it fired up on the first kick.  Tony took her for a spin after warming it up and seemed happy.

This is what it’s all about.  Welcome to your single kick CB400F, Tony.

Tony and my shop helpers loading up the bike....

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