Engine Tear Down and Rear Sets

Stripped Frame and Pulled Engine 

Stripping it down to the frame turned out to be the right call because a lot of the frame modifications would have been impossible without having complete access to it.  It was surprisingly easier than I thought it would be; nothing was seized or stripped.  The side of the frame even comes right off to let the motor slip out, which im sure would make my wife happy after she reads this because I would have asked her to help me.  The immediate plan is to inspect, clean, paint and rebuild the engine.  After studying the DOHC (dual overhead cam) motor bible and watching some youtube vidoes, I started disassembling the motor.

Engine Tear Down

It seems overwhelming at first but if you take your time and stay organized it really isn't a big deal.  At first I was just going to clean it and replace the gaskets, but when I told my dad (frequent engine rebuilder) this plan, it was as if I told him I murdered someone; actually I think he would have taken that better... We all thought the biggest disappointment as a son is getting a girl pregnant in high school, no; its for sure disassembling a motor and then telling him you're not going to rehone the cylinders.  After watching his eyes tell me I was dead to him I decided to properly rebuild it.  If it's worth doing, it's worth doing right.

This means removing carbon buildup, cleaning and checking gasket mating surfaces, checking cam clearances, adjusting the shim buckets, checking for leaking (and maybe replacing) valve seals, rehoning the cylinders, changing piston rings, etc.  The jury is still out on whether i'm going to be splitting the crankcase to take a look at the piston rods and bearing surfaces (I really dont want to...)  In between researching and scouring ebay for parts, i'll be scrubbing my life away trying to get the carbon build up off the piston heads and the valves; you can see the tops of the pistons are black.

European CB750F

My 1981 CB750K

To do the cafe style rear sets, which are just brackets that allow you to move the pegs and foot controls back to allow for a different seating position, I need to find the right "Honda looking" bracket.  Luckily and annoyingly, Honda makes rear sets for their european Sports Kit CB750Fs and the Australian CB750Ks, both of which are bolt on options.  I like the eurpoean sports kit brackets because they look a little more substantial.  You can see that the european bike has those aluminum brackets that pull the pegs and controls behind the engine whereas my bike has them on the back edge of the engine near the oil reso.  To make them work I needed to cut off the welded-on brackets as they would get in the way of the new bolt on rear sets.  I also needed new swing arm and engine hanger bolts because the new brackets use those bolts meaning the ones I have are too short.  I can easily get a swing arm bolt from an american CB750F which is the right length, but the engine hanger bolt is weird.  The american CB750Ks have 12mm bolts whereas the longer bolts used on the European and Aussie bikes are 10mm... I've yet to find the right solution but I will update when I do.

Modified Frame

I made friends with a new angle grinder and we chopped off those welded-on brackets, side cover brackets and built-in bike stand.  Then I grinded off the welds back down to the frame and left it rough for sanding later.  I have to be careful to leave all the original information and warning plates on there so as to appear stock.  Next for the frame is removing the tail of the bike and welding on a cafe hoop and cowl brackets.  I won't know how I want to mount it until I figure out what i'm doing for the cowl, so i'm leaving that for later.





For now i'll continue with the engine rebuild and finalizing my solution for the rear sets.  I have the rear set brackets and im waiting on the new brake lever and shifter assembly; both from the european CB750F.  The CB750F has rear disc brakes so I also have to figure out how to make the brake lever work and adjust for drum brakes, everything that made them work was cut off with the welded-on wing brackets.

Status: (telling myself) I'm not in over my head yet.