FM Bike Works

I didn’t get a super long amount of time on the bike, but wanted to see if I couldn’t figure out where the tapping was coming from.  One possible occurrence can generally be from the tension on the cam chain needing adjusting.  So, I set out to remedy this and found the front lock nut and the two rear lock nuts in charge of adjustment.  The instructions for this bike is pretty simple:

• Start the engine, let it idle
• Loosen then tighten the front lock nut and bolt
• Loosen then tighten the two rear lock nuts

Got the engine started, loosened the front lock nut and bolt, and then realized that I couldn’t tighten it.

Stripped hole for the front cam chain lock nut.

Might be a little hard to see, but hole that the lock nut came from is stripped clean.  Kind of hard to tighten it down when there are no threads to tighten it with.  Set out to get a helicoil set to fix this, but it turns out that the clearance to drill out the hole is interrupted by the frame itself.  Have some ideas to fix this, but it’s going to have to wait.

Had some time today to do some work on the bike.  After cleaning the carbs and airbox and lots of degreaser everywhere else, I put the parts back on the bike.  Like I mentioned before, I’ve learned a little bit more about DOHC engines, so putting the airbox and carbs back on was the best solution.  In addition, I decided to hook back up the emissions control run-off box (it was dangling under the battery not connected to anything).  I was worried about some of the connections the previous owners did, so this at least gets the bike back to what it used to be.

I’ve also decided to put the previous bars back on.  The drag bar was by far cooler looking, but with the air-based front suspension ran right into the controls.  Pushing the original bar back looks better than it did, but I’m keeping my eye on something to do with those bars.

Then came the surprises of the day.  After put everything back on the bike I decided to start it up and see how it goes.  Nothing.  Turns out a wire connected to the key ignition disconnected.

Broken ignition wire.

The fix was pretty quick, I just didn’t expect this issue.  After I patched the cable, the bike was able to start up.  Even took it for a ride down the road and back.  Still work to do, but good to know some parts of it are working.

The next surprise came when I decided to check the final drive and subtransmission oil.  Normally you set the bike level and check the amount via the side mounted check bolt.  Normally this doesn’t have too much of a problem.  Normally oil doesn’t come spewing out of these holes.  Todays seems to be a different day.

Draining the final drive oil.

Draining of the subtransmission.

After the initial shock, I drained them both and refilled with Hypoid Oil; this time to the correct level.

The CB900c has a subtransmission which allows you to select between Hi and Low gear.  Effectively this means that the bike has 10 gears total (though most don’t really use it this way).  One of the previous owners thought it would be cool to swap the subtransmission selector with something a little more snazzy.

Skull based selector switch

Now I’m sure some will like it, but I personally thought it was more in the way than anything else.  So, I found a standard one and did the quick swap.

Standard selector switch.

I think it looks much better (and the skull doesn’t keep bumping into my leg).

In addition, I noticed some issues with the readout on the speedometer.  So I pulled the handle bar off and the speedometer/tachometer.  I’ll disassemble it later and see what’s wrong.

Needed to remove and drain the tank to get better access to the bulk of the bike.  From the year of sitting outside, the bike’s pretty dirty–leaves, grime, etc.  I was able to clean some of it off, but this is going to be an ongoing process.

My plan is to make my way through most of this bike, and the most obvious place was to start at the carbs. After a little bit of effort, I had the airbox and the carbs off the bike.  When removing the carburetor pack, I found that the throttle push cable was snapped.  The other cables (throttle pull cable, choke cable) seem alright, but I’ll need to inspect them a bit more as well.  The airbox has a bit of oil in it, but at the moment it doesn’t seem to be too much to worry about, mostly just blow-by from the crankcase and subtransmission.  Likely the accumulation is from this bike not be able to actually get warm enough to ride.

Removed carbs and airbox

Another view of the removed airbox and glove box.

My original thought was to completely remove the airbox and replace with pod filters. Looking at some examples online, I really like the cleaner look this would give. But, as I research a little bit more, it seems that these DOHC Honda’s don’t particularly like not having their stock airbox. I’ve got the parts for the pod conversion, but I think I’ll shelve them for a later time and focus on just getting things working again.

As time was pretty limited today, I decided to also tackle that handle bar. I’m not a fan of the big handle bars, preferring the much sportier look of cafe racers. As such, I needed to get rid of the bars that came on the bike, and opted for much leaner looking drag bars. Since I needed to pull all the controls off the bars, this gave me a chance to also yank out the bad throttle cable.

Drag handlebars installed

Carbs pulled, airbox pulled, and handlebars swapped.

New bars in place, I think the bike is going to look a lot better. Storms are moving in and other errands are needed to be done; so it’s time to see what all has been pulled off so far.

Parts removed from this venture.

I recently picked up a 1981 Honda CB900 C.  It’s in pretty rough shape, having sat on a driveway for a year or so. Here’s a couple pictures:

Starting point of the bobber.

Back side view of the bobber.

The bike has troubles starting, the tank has tons of surface rust, and that’s just the beginning of the problems.  It’ll be fun to figure out what all’s going on.  In addition to the overall fix-up, the previous owners had begun turning the bike into a bobber and I’m really liking the style; so I’m going to see what it’s going to take to finish all of that up.

In the past few days of working on the bike I was able to clear up a couple issues immediately.  The wires to the solenoid weren’t doing very well, so I re-terminated a couple of the wires and made a better connection.

View of the wiring to the solenoid. Quite a mess.

I’d like to find a housing for the wire connection (without having to rewire the entire loom), so I’m on the lookout.  In the meantime, I’ll likely heat wrap what’s there just to protect it a little bit from the elements.

In addition to this, I drained the oil and replaced it and the oil filter.  The bike fired up, but there’s some noticeable tapping, as well as one of the headers being stone cold.  It’s not going to be a quick project, but once it’s done you can tell this bike is going to be fun.