Built for speed

JSharpPhoto · Post by **JSharpPhoto** » Wed Oct 17, 2012 11:48 pm

I am in the process of planning my rebuild on my newly acquired CB77. I know it's going to be difficult, but I want to be able to do "the Ton", even if I need a few miles of straight highway to get there.

I'm going to (attempt) to accomplish this through minimizing the bike's weight, bigger or upjetted carbs, velocity stacks or less restrictive air filters, more open exhausts and some different sprockets.

I have 2 questions.

1. Am I high? Is this goal unattainable?
2. Will "crossing the gears" in the tranny be enough to offset the low end lag created by the larger sprockets?

I'm new to hondas, but not new to bikes. I've spent a few weeks poking around on dotheton, but there doesn't seem to be many CB77's over there.

G-Man · Post by **G-Man** » Thu Oct 18, 2012 2:02 am

It's not impossible but it is a stretch for these bikes if you want to do it regularly.

A big bore conversion will help. 337 (+3mmm over) or 350 (new liners and pistons)

Reducing weight and crossing gears will help acceleration but not top speed. How much do you weigh? What will you be wearing?

Speed is about power and aerodynamic drag. Velocity stacks and re-jetting may help a little but porting the head professionally will make a bigger difference. As you up the power / reduce drag you will be able to gear up accordingly by reducing the size of the rear sprocket.

The engine will need to be in good condition with good valves / seats, good piston ring sealing etc.

There are some good articles here on improving these bikes. See Vince Lupo's recent work in his thread "Japan Meets Britain"

Take Care

G

JSharpPhoto · Post by **JSharpPhoto** » Thu Oct 18, 2012 9:07 am

That's very reassuring. At the point where I do this, I will weigh 175. I wear normal riding gear.

I don't need to do this often, or for long. But if I have a ton up patch on my jacket, I need there to be truth behind it.

Snakeoil · Post by **Snakeoil** » Thu Oct 18, 2012 9:53 am

Put a racing fairing on the bike. That will help you a lot. You probably want to find a long downhill stretch as well. After all the ton is a ton whether you do it on the flat or downhill, right? I had my little S90 approaching 70 mph indicated going downhill in a full tuck.

Run your tires hard.

Just make sure that the hill does not end at a Tee intersection at the bottom.

If all else fails, you could always strap a surplus JATO rocket to the frame. Don't forget to hang on.

Good luck,
Rob

JSharpPhoto · Post by **JSharpPhoto** » Thu Oct 18, 2012 10:52 am

I know just the hill!

In all this planning, I kind of forgot about gravity.

So I know, how accurate are these speedometers?

G-Man · Post by **G-Man** » Thu Oct 18, 2012 11:21 am

You could always haul it up to 24 miles high and throw it and yourself off a balloon. I hear that's good for at least 800mph!!

G

bonjour · Post by **bonjour** » Thu Oct 18, 2012 12:01 pm

I don't think you have to do alot to get the ton.

My CB77 is all original and ive driven mine to 140km/h (what that ? 85mph?)
Plenty of power left but I thought is was 'enough' I don't want to put mine to the test, im not a wild rider. I was convinced it could have reached 180km/h it sounded and functioned very healthy, not a single moment while accelerating I felt it got slower, or reaching it's peak. It keeps on going !

Best way to get more top-rpm performance is probably an electronic ignition and get rid of the advancer in the cam (because it's sloppy due to the cam-chain, it bounces around so to speak)

And maybe a 'faster' chain drive ratio.

That should be it in my opinion.

I shouldn't be a big deal.

Just make sure the engine is in good shape.