Engine RPM's at freeway speed?

Hi All, My 81 KZ1000m runs at about 5000 rpm at 70 mph. I know the redline for this bike is 8500 but it feels like the bike is really revving and speed control is jerky.I keep grabbing for another gear but there isn't one... Were these bikes purposely geared low for a reason? Can I drop the RPM's by going to another sprocket setup? If so--what will work, and what are the benefits/drawbacks?
Thanks in advance.
Grant.

Grant:
My 900 is stock with a 15/35 front/rear sprocket setup. With those sprockets, I'm seeing about 4000 rpm at 65 mph, and about 5000 rpm at 75 mph. Note: My tach is FAR from steady at these speeds, so my rpm is more like an estimate.
Don't know what your sprocket ratio is, but it sounds close to mine.
I just ordered a new front sprocket, and I decided to stay with the 15T. It was good enough for Big K, so it's good enough for me.

Here's a link to an Excel spreadsheet that will let you play with different front/rear combinations:

kzrider.com/component/option,com_joomlab...id,2/id,24312/#24312

Click on the link in the first post, then copy the spreadsheet to your computer.
If you go with a 16T front sprocket, then your accelation my suffer a tad, but you've go tons of power, so, unless you're drag racing, I don't think you'll care.

One other thing: The 16T is a bigger sprocket. Just a little, but you need to make sure you have clearance around the front sprocket 'fender' that is under the sprocket cover.

you can change your gearing,but remember it is going to affect performance at other speeds as well.you can also try a little taller rear tire.

Thanks for the advice. Unfortunately I can't go with a taller tire as I'm quite vertically challenged. I will however follow up with the drive ratio worksheet.

I surmise that you guys are saying that 5000 rpm's at 70 to 75 mph is normal for this type of bike and I shouldn't be alarmed that the engine will wear out prematurely?
Grant.

By vertically challanged do you mean to say you are short, or do you just not stand up straight...?

As for your gearing: 5K is about what I see on the open road (unless I'm speeding as I often do...)

If you spend a lot of time cruising, you'll like the taller gearing. But if you spend a lot of time in town, the taller gearing will cause you to slip your clutch more at each and every light. It will wear out sooner.

P.S. ...I'm 5'6" and I'm in the process of lowering my bike an inch.

I don't remember the RPM's or the tooth count after 23 years but on my 80 KZ1000 I changed to the biggest front sproket that would fit without grinding the case and the smallest rear sproket and I could still smoke the tire or bring the front end up with ease depending on where I sat. Droped the Hiway RPM's and made for a much smoother ride.I saw only benefits and NO draw backs. The 1000 has plenty of power. If it were a smaller bike/less power then you might get in trouble changing the ratio.

By vertically challenged, I meant short--5'6". I can touch with both feet but barely. :woohoo:

I'm running a Z900. I had a 15/35 combo on but found I was often sitting on that 5000rpm mark, which is a pain, as it's around there that the vibes set in. Currently I have a 16/35 set on, and although a few people suggested it may be too high, I've found it just right for touring speeds. In fact I can't really fault it at all (Unless you want to drag race your bike)

With stock 15/39 (2.6) gearing, my 1981 KZ1000M1 CSR revs about a comfortable 4250 or ½ of redline at an indicated 70 mph. I know my speedometer reads higher than actual. A previous owner may have changed the sprocket ratio on yours.

Post edited by: oldcoldankles, at: 2006/08/28 09:50

I remember reading something from the KZ900 Owner's Manual about breaking in the new engine.
It has a table that shows max speeds/rpms during the first few hundred miles.
Then it has a note that says running the engine at these low engine speeds may foul the plugs, so check the plugs after break-in and change them if necessary.
I think my bike runs better at 4000 than 5000 rpm. It's definitely smoother. I wonder if that's low enough to cause plug fouling?