When I first got my '79 CB650 it had barely enough power to go past 70mph. That had to change! I replaced the stock 90 main jets with 102.5's which made the bike run a hair rich. I removed the stock airbox cover and that helped a ton, but was still running a bit on the wet side. I drilled out my exhaust a little and that did the trick. The next couple of days I drove it to work, putted around town going anywhere from 30 to 55. Gave it plenty of thrashing through the gears. It'd bring up the front tire in 1st and 2nd! Finally today I deemed it healthy enough for the highway.
Going east on I-435 keeping up with traffic I was running a healthy 75mph. Running smooth, not so much of a miss, backfire, stutter, or anything that would make me want to slow down. After about 10 minutes of cruising I-435 E curved and turned into I-435 N on the Missouri side of town. A decent-looking Ford Probe pulled up next to me with an even better-looking female driver. She looked over at my old, raggedy-looking bike (dent tank, bad paint, old oil on the engine, etc.) laughed and passed me. Not to be one to be laughed at, I let her have it. Opened up the throttle (not yet WOT) and sped off to about 95mph. I was amazed!! I still had plenty of throttle left, so I gave her all she had. At about 105 the controlls get kind of touchy. At 115 it got downright scarry. THE DAMN THING WAS STILL ACCELERATING! At around 120 mph I'd finally had enough and slowed it down. There was still plenty of horsepower left in this old 650. Just not enough confidence in the suspension, transmission, tires, chain, sprocket, and most of all me. Besides, I couldn't imagine getting a 120 mph ticket on my bike (probably be arrested). Also, it was getting precariously close to redline and I didn't want to push the engine to its (or my) death.
Just typing about it speeds up my heart. What a rush!
A lot of people would question my speedometer's accuracy. Normally I would, also, but the specs match my RPM to my speed pretty accurately. I can imane one could be off (either speedo or tach), but both being off, and to the same degree, is a lot less likely.
On a side note, according to some documents I've found, the 627cc motor is rated at around 49hp at 8100rpm, weighs 365 lbs, and obviously has a top-end up and above 120mph. That's 0.134 hp per pound.
The mighty 750's 736cc motor produces 67hp at 8000rpm while carrying 517lbs of weight. That divides out to 0.129hp per pound.
CB650=.134hp/lb
CB750=.129hp/lb
Hmmmmm........
