this is my old 1979, now owned by my brother:
IMG_0029Here is the laundry list of things to check:
- Starter Clutch. It isn't a matter of if it fails, but when. most are already on their last leg. If the bike is already apart replacing this is a no brainer. There is a mod to use a more modern R6 starter clutch because it uses the same splines and is the same size, it just requires some re-drilling. Research it on CB1100F.net
- Cam chains. If left unattended or un adjusted these will eventually saw the block in half. If you are taking apart the engine then might as well replace all the followers and adjusters and inspect the block for wear. I'm not kidding about it sawing the block in half, the metal is thin there and it will literally wear it away until it cracks in half. Seen it happen on more than a few.
- Electricals: they are generally poor for this era bike. Clean contacts are key. My bike in 10 years of ownership in the same family has been through 3 regulator/rectifiers, 1 set of coils, 1 stator and rotor, and 1 set of pulse controllers. It is common for these bikes to just stop charging for no reason.
- Previous owners: every one I have owned (1 cb750F, 2 900Fs, and 2 1100Fs) weeps or leaks oil from somewhere. And usually that is stemmed by some dude using a fist full of silicone sealant to stop the weep. These bikes run hot so warpage is common - if you can run an oil cooler setup on your 750 from the 900F. Also people love to hack the stock harness for aftermarket stuff so....be mindful of that.
upgrades:
You already mentioned a freddie replica so I will just mention later interceptor VF750F wheels as a good option. they are the correct 18" rear, 16" front and they look like replica dymags if you file the castings off and paint them black or gold. I am talking about the second gen interceptor which was from the late 1980's through the early 90's. Rear is a bolt on, front requires a different front end (most use a first year hurricane CBR1000 because it is a bolt on and only 1" shorter than stock). I will however advocate for the cbr600f2 wheel/fork upgrade which puts 17" wheels at both ends. I've ridden a 900F setup like this and it is much nicer and the access to sportbike rubber is better.
If you are keeping the stock forks, the 1981-82 dual piston caliper is worth it's weight in gold. esp with braided lines. I just did this to bro's 1979 bike and it stops. Also it's cheaper to service and easier to get pads for since they used these calipers on a ton of other bikes.
hondaman already mentioned the swingarm bushings so I will just mention that a cb1100F steel box arm is stronger and better looking than the stock piece. I think Calfab also makes alloy arms for these bikes.
Ohlins sells shocks for them and cb1100f does a group buy sometimes. totally worth it if you can do it. the cb900F and 1100F used remote res shocks that are ok if not worn out but most are. Stock shocks were dual damping with a switch on the bottom to change from soft to hard - most got thrown out but if you have a set and they still work - try them, they are kind of neat. I run 14" vipex shocks on mine that were setup a long time ago. They look like cheap chinese shocks because they are, but they were spec'ed by a cb1100F member who worked in china so they are better than the garbage being sold on ebay that looks like them. They are out of the box setup for a 200lbs+ rider so the number 1 complaint is that they are too stiff.
Lots of parts sharing with other bikes and there is a lot of cool bolt on stuff. Honda sold factory rearsets on all the foreign models called a sport kit. Sport kits for the cb1100F are the most coveted because they are a lattice design and not a sold stock foot plate. Otherwise it's an easy upgrade, I just paid $140 for mine shipped from england - try getting aftermarket rearsets for that. Also foreign models used 18" front wheels instead of 19", and many used the boomerang comstar in gold or silver anodizing. We only got the boomerang comstar on the cx500 turbo so we can only use the front off that bike (cx500 turbos are shaft drive), but even mexican interceptors used boomerang comstars. They are a similar design to PM chicanes and Astralight wheels so they have the race look to them more so than a stock comstar.
A little known fact is foreign cbF's had an option for a glove box/stash box in the tail section. They come up on ebay from time to time but are kind of rare. It's a nice little touch since we never got them in the states.