A buddy of mine is considering a fix it upper road bike for fun and to learn (prior dirt bike rider). I still go by the rule of thumb that 600cc is iffy for beginners but a lot of used 1980s bikes are 600cc-1000c and less powerful than their modern equivalent.
Is the performance somewhat comparable to modern engines with same CC? Weight?
I don't think the engine size is as much a factor as the geometry for a new rider. Of course mentality is the most critical. Geometry is function of the type of riding. If this is in a city with congested roads I'd opt for something more upright with better visibility. Back then you could get trail bikes and ride them on the road, and they were very easy to ride unless you were on a very windy freeway. My first bike was a Honda FT500 and it was good for a learner.
You are correct in hesitation to put the new rider on a modern liter bike, or even a modern 600cc sport bike.
Until the late 90's motorcycles always had much better acceleration than cars so it was easy to get ahead of the traffic from a red light and get away from the other cars. In the late 90's cars started getting much faster off the line and motorcycles started getting ridiculously fast and light. Regular riders on their 80's bikes lost the assumed lead they had off the line and had to adjust riding style (usually this was subconscious as the learned to check their sides more)
If he is an experienced motocross rider on a 450cc, he might be comfortable on the road with a 600cc. Granted, riding on the street is a different beast than on the track. Most of the time it's not yourself that you have to worry about, but everyone else. People will make a habit of not seeing you. On top of that, you don't want the added risk of a bike that you cannot control.
I would still recommend starting on a small cc bike.
Performance all depends on the manufacturer and specific bike. Some bikes of old can still lay down the rubber compared to bikes of today.
The Honda V-engines were very powerful for their times. When the V65 Magna came out, it was the fastest street bike for its model year. IIRC, the Sabre uses the same engine. That makes the Sabre a very formidable bike, whether it's an 80's bike or what. If the rider is new to riding, it would be my suggestion they not get it because it is a lot of bike. Learn how to ride on a 600cc (or less) bike, because chances are the 1100 is going to be way too much for any beginner.
The design of the engine is going to have a lot to do with how easy the bike is to ride. Is it a V-twin, parallel twin, single, or inline 4? Different engine designs handle throttle response very differently. An inline 4 might get you into trouble if you accidentally give it too much throttle at the wrong time. V-twins tend to have a lot more low end torque. Parallel Twins and Singles are great beginner bikes, but they tend to not have very high displacement. Also the style of bike (Cruiser, Standard, Touring, etc.) will have a lot to do with it as well.
You have mentioned he's looking at a VF1100 Sabre. I am assuming you are asking about comparing it with a modern sports bike.
To answer your question directly: The short answer is that a modern 1000cc bike will have significantly better performance than 30 year old 1000cc bike. In fact a modern 600 will probably have better power to weight ratio.
Rough comparison a 1980 GS1000 made about 100hp. A modern 1000cc sports bike will make nearly twice that.
A modern CBR600 makes about 100hp. However it's probably about 50kg lighter.
However your post and other people's replies raise a few issues. Yes modern bikes are lighter, faster and more reliable, they also handle better and stop faster. But they're also more expensive and not everyone wants a modern sports bike.
Maybe you should be asking your friend what type of bike he wants to ride. What does he want to do with it? If that's what he wants.. well that's what he wants.
A VF1100 was and still is a capable bike. But by today's standards it will be considered heavy, and it's handling and braking will be considered poor. Also as it's now 30 years old it's probably in need of significant maintenance.
Think: 589lb/100hp+ bike capable of >120mph with soggy suspension and crappy brakes.
My other thought is that if your friend hasn't ridden for a long time and his last experience was on a dirt bike he might be in for a nasty surprise. Big heavy 30 year old road bikes don't turn or stop like a dirt bike or sports bike. He'll learn that the hard way the first day he tries riding fast on a windy road or wants to stop in a hurry.
However... Provided your friend is realistic about this bike, maintains it, and rides it within both his and the bikes limits he'll be fine.
If he really is a novice. There are a lot of other bikes out there that are more learner friendly that will help him gain confidence and proficiency faster.
