top speed rpm relationship

What is the stock kz650 rpm top speed based off of. Like in the manual the top speed is like 110 or something. What gear rpms is it based off of? Redline rpms in each gear?.

Generally top speed will be top gear pinned in the redline, and flat on the tank to reduce wind resistance.

Gearing it up to reduce your rpms won't give you a higher top speed, although it will give you less buzz at cruising speeds...but unlikely beter mpg. These bikes, even though old school dinosaurs, have a lot of overlap on the cams :
the motor is actually more efficient at higher rpms. Valve overlap wastes fuel at smaller throttle openings.

look in the front of your Kawasaki Service Manual. There are charts there that show all the info you request. The top speed for a stock kz650 is right around 120 mph at 9000 rpm in 5th gear. Ed

I have a KZ650 79 C3 model, and my top speed ever recorded was 153mph. RPM from what I can remember was around 10,750rpm. I'm not bragging, but just to let you know. I don't rightly remember what the tooth numbers were on both chain sprockets. She was slow in getting after 130mph, maybe 2-3 more miles to totally top out, and I was awaiting for a rod to come loose, or drive chain fly off, but they didn't and I slowed her down. Never did that again, but routinely ran here at redline for many miles.

Mine you, I was stationed in Germany in 1983 when I did this, and on the autobahn between Trier and Wittlich. I was running Z rated tires, and no wind screen. I love my bike, and still have her. She does get to oscillating if you are not careful beginning at 105mpg, and you must bear with much weight on the front handle bars.

I found in 1998 when I went to Morocco (Africa) from Frankfurt Germany, that the front oscillating is caused by the bike having too much weight on the front end. Thought I was going to die that day.

As for economy, normally ran 95MPH fully loaded, and obtained 53mpg constantly. If you are always full throttle, you might well expect about 20-25mpg.

Ride smart and be safe.

WOW!!! I've never seen a late 70's KZ650 true out at over about 125mph!

A remarkable machine indeed! How do you know the bike was going 153 mph; what did you use to measure the speed? Ed

Yah I could probably hit 125 at just under9,500 but that's about it and that would take a little tale wind...... any head wind and forget that. Hit 9,700 one day but that was with about a 20 mile per hour tale wind and a slight angle on the road for about a mile. A factory manual has the chart like Ed says that shows speed in each gear........ hoping the slightly bigger 750 cam will help a little but not expecting much more...... would need a wilder GPZ cam to get in the mid 10,500 range.

Maybe he was looking at the kph scale.

TexasKZ wrote: Maybe he was looking at the kph scale.

Agree! That's why I asked how he measured 153 mph. The highest speed marked on the KZ650 speedometer is 140 mph and gps units were not yet available. Also, I don't understand how he was running Z rated tires in 1983. I believe they were first made available for bikes in the early 1990's. :whistle: Ed

I used to run the autobahn and the cars where geared differant. VW of mine in the 70s 220 k

Hello All!
Let's keep all civil!

Points... I ditched them when the Dyna Mark III came out and have ran it ever since. If the Dyna ever "misses" then one should immediately check the charging system to ensure it is not OVER charging.

The tires were available at least in Germany at the time. They ran me around 180 dollars each, at the time. Expensive, but the way I rode the roads over there, I considered the safety factor to be worth it. I was 140 lbs then too, and 150 today.

The speed was obtained by an optical sensing circuit going through the front spokes, thus counting the times per second the light is broken, then convert that by circumference of the tire, gives you inches or feet per second. Most accurate. Being mount on the front, eliminated any wheel skip on the back tire if that was being used. There are many other ways the same can be accomplished. I've been in electronics since 1978, an today, the same can be done with fewer parts, time and cost. Today, I'll either get my GPS out or my radar gun. No need to create anything.

Other notes, to get the best breathing to the engine, use the stock airbox. Pods, just look cool, give a pleasing sound from the carbs sucking in air, but are worthless in the performance arena.The Mikuni slidebores were VERY sensitive with airflow, thus if running pods, you could feel the motor surging as the air around the bike would flow at different speeds around each pod. After exhausting testing with the K&N pods I took them off and settled for a K&N replacement for the factory airfilter. Never looked back.

To get the most out of the 650 motor, valves and carb must be exactly adjusted. I learned early on, if it takes less than 3 hours to tweak the carbs, I was going to pull them off and do it again, until I got it right. A quickie on the carbs, then one has not adjusted them properly. Precision takes time and effort, and if one is anal about it, then they will reap the rewards of their patience.

Jetting and needle position is absolutely critical to proper performance on the KZ if ones excepts maximum power. In Germany I had the luxury to run the autobahns testing top end performance, and spent any a mile doing so. In the early 80's, the traffic was "light" compared today, much less 10 years ago.

I personally know of no roads in the states where one can run the bike WOT / max speed (legally) for 30 minutes or more. German roads back then were awesome, the one ones better would be in Switzerland, but not straight!

Also as stated above, an like wise, I had a BMW 320 6 cylinder, she had 240KM on the speedo, and she would bury the peg, and would do it while the peddle was to the floor. Again tuning is a critical part of the whole. I can give great advice on BMWers from that era, because I dit it. But the forum is not about BMW's but KZ's, so I'll stick to that.

I consider my 650, my trusty stead and plan never to part with her. A fine piece of workman ship and a thrill to ride.

Be safe out there!!

I'll be civil and simply state a fact that can be easily verified.

Goodyear introduced the world's first Z speed rated tire in 1987. The tire was made for high speed cars and was named the Goodyear ZR-S. It was designed to operate at speeds exceeding 149 mph. Z rated motorcycle tires were not available until later. There were no Z rated motorcycle or car tires available in 1983. Ed

books.google.com/books?id=LjTIkcprsCQC&p...0ZR-S%201984&f=false