It’s funny that someone had recently asked me about what my dream bike list was and after the highly sought-after RC30, I had mentioned the Honda CB1100R, which was sold in very limited quantities in non-US markets. They have that cool look of the vintage endurance racers from that era and were in fact built to satisfy the homologation requirements to race as a production-based machine in world championship events. The production numbers were approximately 500 in 1981, 1500 each in 1982-83.
Unlike the svelte 400 lb RC30, which is a 750cc street bike version of their highly successful V-4 racing machine, the CB1100R is based on the 1983 CB1100F street bike which was sold in the US and is a powerful, but hefty machine, weighing in nearly 518 lbs dry. The fuel tank is almost 7 gallons, so the wet weight increases dramatically. See: https://en.wikipedia.org/wiki/Honda_CB1100R for an overview. They were produced from 1980-83 and each version (B, C, D) has unique features that do not interchange with the other models.
Various articles have been written by others, and published, on the origins of the CB1100R, as per the below links. https://www.oldbikemag.com.au/honda-cb1100r-machine-mission/ https://classic-motorbikes.net/honda-cb1100r-rare-road-racer/ https://en.wikipedia.org/wiki/Honda_CB1100R
So, surprisingly, a CB1100R popped up on Facebook Marketplace and the posting gave “San Diego” as the location of the bike. The owner was a local Motorcycle Wrangler, as I would describe him. I had looked at some of his bikes when he lived in a different location some years ago. He was always turning over new stock and seemed to be able to find some unique bikes, but I had never worked a deal with him. More surprises were revealed when he mentioned that he had TWO of them for sale!
I made an appointment to go and see him and his current stock of machines. He had a Z1-R Kawasaki sitting out in front of his garage and mentioned that there were FIVE Kawasaki 750 Turbo machines stacked inside of a storage container. He was reluctant to reveal how he got his hands on two CB1100R machines with OR titles, but he just said that he was at the right place at the right time, overhearing a conversation at a local auction house. So, he snapped them up and posted them on Facebook.
The bikes were supposedly from the UK and showed the kind of “patina” that comes on bikes that are used and ridden in a mostly humid country. The key tag for the bike was a dealer item with the name of a motorcycle dealer in South Africa, though!
The brake lever pulled right to the handlebars and the plastic master cylinder reservoir was definitely showing its age. The bike supposedly ran, the inside of the aluminum tank was clean and the bike appeared to be fairly complete but weathered. It had pod filters on the carbs, but came with the stock air box and a new windscreen. The standard 4 into 2 muffler system had been replaced by a 4 into 1 collector, which looked fairly new. The tires were worn and one supposes that the drive chain and rear wheel dampers would need replacement. It was a project, but a very rare machine to be found anywhere in the US, much less right in SoCal.
One bike had already been sold, which apparently had 90k kilometers on it. The remaining one was showing about 46k which is about 28k miles. They both looked in similar condition, but the remaining one had its price reduced by $2k. I have owned several CBX six-cylinder machines and worked on several DOHC Honda 750-1000 machines when I was working at a Honda shop in the 1980s, so the engines are not unknown to me. They do have 4 valves per cylinder and after 40 years, the valve stem seals are undoubtedly hardened causing oil consumption. When cared for, the engines have a long life, but there have been instances of broken cam chains or tensioners leading to expensive repairs.
The basic 1100 engine was tweaked with hot cams and a 10:1 compression ratio so premium fuel is required to feed the 115 horsepower powerplant. The bikes were built to compete in 6-12 hour endurance races in Europe and Australia, so were not your average EPA-tamed powerplants.
Fortunately, Matt, the owner of the moment, agreed to deliver the bike to me despite not having any front brakes and we made a deal that I hope I will not regret. Be careful of what you wish for….
Arrival and evaluation.
Arrival:
Between the two of us, we managed to wrestle the big bike off of his truck and pushed it up onto my motorcycle rack without incident. Having only a long side stand, the bike wouldn’t stay on the rack as the stand end extended past the edges of the rack. Fortunately, I did have a rear bike stand which was slid up underneath the swing arm and raised the back wheel up centering the bike on the work stand.
Years of neglect were apparent, especially with the condition of the master cylinder, which had lost much of the factory black coating and the exposed aluminum badly corroded. I was able to disassemble the master cylinder and it will get a bath in phosphoric acid to neutralize the corrosion and then give a better view of the overall condition. I had already purchased a $40 repair kit for it, plus another $25 for the plastic reservoir so I hoped that it would be repairable.
The bike had gone down on the aftermarket 4:1 muffler, which suffered a pavement grind spot along the lower edge.
The bike did come with an Oregon title that had a strange VIN number that wasn’t from Honda. As it had no VIN number up where it belongs on the steering head, the only conclusion is that it has a new frame installed and the VIN number originated from Oregon. I actually reached the owner on the title in OR, but he was a wrangler as well and had no clear memory of the bike.
The bike had a loose combination of non-OEM nuts, bolts and other fasteners. The fairing and rear tail light assemblies are all mounted on little rubber mounts which incorporate 6mm studs for mounting. Two of the rear ones were severed and the fronts were missing altogether. Removing the gas tank was a revelation in that it was a 7-gallon tank that weighed just a few pounds due to its aluminum construction.
I was able to remove the carburetors and inspect them briefly. There was fairly fresh fuel inside and no signs of contamination or corrosion, so I didn’t go further into them. The intake manifolds were rock-hard and when the aftermarket replacements arrived, it was evident that the Chinese copies for $16 a set were just 4 copies of one of the four different part number manifolds used on the 900-1100 engines. The replacement OEM manifolds were $125 a set.
When the old manifolds were removed, there were trails of crystalized gasoline/oil in the ports, so it is hard to tell if that was old carb residues from sitting for many years or something more sinister. I’m sure that the valve stem seals need replacing. I did that once on a CBX by just lowering the engine in the frame and removing the cylinder head. That’s not possible in a 1100 chassis so the whole lump would need to be extracted from the chassis. The bike is sitting on a rear swing arm stand on my bike bench, only having a side stand to prop it up with, and because of the length, it extends past the edge of the bike lift.
Repairs
I was able to extract the rear wheel and have a new tire installed. The rear brake system was empty, so will need rebuilding like most everything else on this bike. I am not sure how I can support the frame to remove the front wheel and forks. The seals are leaking of course. The tire date codes were from 2011, so everything needs attention.
A gel battery was ordered, but was much smaller than the battery box. With the CBX bikes, there was a spacer that could be used to install a smaller battery than the GL Goldwing unit that takes up the whole space. I wound up using some wooden spacers to help secure the battery in the box, but it wasn’t the greatest remedy for the situation. I jumpered the solenoid and the starter motor spun the engine over okay.
Removing the instruments from the cowling, revealed a cheesy strip of metal that was used to hold them in place. The original steel instrument bracket was not included and are NLA hen’s teeth out in the world. The speedometer was removed as the reset trip meter was cockeyed and the reset knob and shaft were missing. The meter was sent to Foreign Speedometer who observed that the speedometer was similar to the later CBX units. In a desperate search for replacement parts, I contacted Tim’s CBX parts online and he sifted through a pile of old units coming up with just one that was a match. He kindly sold the unit for $50 including shipping to the speedometer shop.
Forks were disassembled and new seals installed, but the bottoms of the fork tubes were deeply scored with no apparent reason or source of why they would have become damaged like that.
I managed to wrestle both wheels off with the bike supported on jackstands under the frame. The rear wheel had a lot of corrosion which took about a half hour to remove down to the parent metal so the tire would fit the rim securely. The front wheel was taken to a local motorcycle tire shop and they swapped out the rubber with no comments about the rim condition. The only way I could remove the front wheel safely was to remove the axle clamps, pull each fork up through the triple clamps and roll the wheel out from underneath it all.
The master cylinder was successfully rebuilt and used to push out the right-side caliper pistons. They came out all blued with signs of severe overheating, either from racing or from sticking in the calipers and dragging the rotor for a while. A lot of the brake parts were shared with other models, many of which were for the CB900-1100F bikes.
Apparently, the brake calipers came from a related model, but the rear caliper pistons were 27mm instead of the 32mm specified. Using the microfiche parts illustrations on www.cmsnl.com was helpful to a point. There is a CB1100R Facebook page and a CB1100R owner’s page that requires a $25 subscription fee, but was worth it for the additional tech information it contained. Slowly all the brake components were rebuilt and installed. Bleeding the twin-piston calipers took some time, but finally, I got a front brake that worked.
The carburetors looked correct, but the codes on the bodies didn’t match what the owners on the FB site had to say about them. The clutch and twin throttle cables were replaced. I had to create a little piece to anchor the choke cable to the handlebar bracket which was missing.
With some new OEM 8mm fuel hose and a brass T fitting I was able to feed some fuel into the carburetors using a remote reservoir and the engine fired up! There is a bit of a rattle in the clutch housing which may be like that on the CBX models which used rubber cushions on the clutch basket. After years of service and age, the rubbers shrink and the cushion effect is nullified. The part number does trace back to the CB1000C and the CB1100F models.
I have to say that it would have been wiser to “Stay in my Lane” instead of having a fantasy of riding this brute on my Sunday rides with my Jamuligan friends. The combination of a lot of one-off parts, plus the condition of what was there has led to a lot of expense and effort, just to get it running and functional. There will be no “restoration” of the bike, but hopefully, there will be some DOHC wizards who desire to bring it back to its former glory. I’ll be keeping my 420 lb NT650 Hawk GT for my Sunday rides, probably forever. But it was an interesting experience to see what Honda’s race team conjured up starting from the CB1100F model and giving it the performance to win 6-hour endurance races repeatedly.
CB1100R anyone?
Bill Silver
aka MrHonda
11/2023
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