Is 9000 rpm too much at 70?

[austexjg]

2009 - 1800 miles - I'm 150 lbs.

I think I may have a tach or ignition problem (from pass post) - I went for a ride today and keep a mental note of the RPMs - 55 mph about 6200 rpm -
70 mph about 9000 rpm - does this seem high? Doing some research on the forum - I found posts about the tach and the IC ignitor - could I have one of these issues? Bike is still under warranty.

[NickH]

I usually hit 8000 rpms at 70. I'm around 225lbs......weight will make a difference.

-Nick-
Posted via Mobile Device

[CZroe]

Originally Posted by NickH

I usually hit 8000 rpms at 70. I'm around 225lbs......weight will make a difference.

-Nick-
Posted via Mobile Device

In the same gear, it's not supposed to. If it works harder/burns more fuel/gets hotter and has the CDI issue, yeah.

[bob706]

70mph @ around 9k rpm doesn't sound like a problem. I wouldn't worry too much.

[andrewexd]

im at the same. you might want to check your clutch freeplay

[backinthesaddleagain]

I find in top gear, stock gearing, stock tires, my revs are about 1,000 more than my speed. 7000 rpm at 60, 8000 rpm at 70.

[nate-bama]

put a 15 tooth up front...run at 9k in 6th..smile

[Cedilla]

I think the tach is just about worthless on these bikes, mine shows anywhere from 7500 to 10k at 70. Seems like ambient temp and bike temp have a role in the different readouts.

[LazinCajun]

Cedilla, that sounds like the infamous CDI problem.

[sombo]

Not sure how much of a difference there is in rpms between the pre-gen and the new-gen. However, on my 1994 ninjette in 6th I run between 1k to 1.5k higher in rpms then mph. So for me at 70 I'm usually around 8500 or so. Since mine is modded for more power it could be you don't have a real problem. But I'm not an expert.

[Alex]

Probably normal, wouldn't worry about it.

[noche_caliente]

Sounds about right to me

[Angel-be-Good]

After my speeding ticket, I stick strictly to indicated 70 mph on the freeway and the tacho is consistently showing 9,000 rpm.

[killerkay3]

im also 150lbs and at 70mph im at 9000rpms too, so i dont think theres a problem

[kkim]

Originally Posted by killerkay3

im also 150lbs and at 70mph im at 9000rpms too, so i dont think theres a problem

rider weight has no effect on engine rpm at a particular road speed. it is a set mechanical function between the engine, f/r sprockets and tire diameter.

[paterick4o8]

70mph in 6th = 9K really?



I am almost certain that at exactly 70mph I'm never @ 9K... usually below whenever I'm at that speed in that gear and I have not made any sprocket changes either

[SteveL]

I am not saying that mine was correct but I had 8500 at 75 mph, what is important is that it reads the same every time.

Steve

[ScorpionNinja]

rider weight ...(the More you weigh, the less your Top Speed will be from a 100 lbs rider off the 100MPH mark)

When i ride 2-UP with dawn on back, my Top end is cut to 90 MPH, solo riding i hit 100 MPH. "IDC about the speedo 10% off thing, blah blah. "

[backinthesaddleagain]

Originally Posted by ScorpionNinja

rider weight ...(the More you weigh, the less your Top Speed will be from a 100 lbs rider off the 100MPH mark)

When i ride 2-UP with dawn on back, my Top end is cut to 90 MPH, solo riding i hit 100 MPH. "IDC about the speedo 10% off thing, blah blah. "

Does the tach show less revs as well with a passenger. My thought would be the added weight reduces mph as you stated, and then rpm would also be less.

[Alex]

Weight doesn't affect what revs show up on the bike at a particular speed. In fact, nothing affects what revs the engine is turning at a particular speed, other than gearing changes. If the passenger causes you to go slower, then sure, the revs would be lower, but only because the speed was lower the same corresponding amount.

[CZroe]

Originally Posted by Alex

...nothing affects what revs the engine is turning at a particular speed, other than gearing changes...

Well worded. We all know that heat can affect what the tach shows with a faulty CDI, but not what speed the engine really is.

[g21-30]

The biggest problem with the faulty CDI is the rev limiter will cut in sooner, before you're truly at the engine's rev limit!!!!

[Midnightrider]

Originally Posted by g21-30

The biggest problem with the faulty CDI is the rev limiter will cut in sooner, before you're truly at the engine's rev limit!!!!

I have run my Ninja up to 14000rpm and the rev limiter has not cut in. I too believe my tach is reading high. Does the rev limiter work off the tach or the cdi unit? Is it possible the cdi unit could be sending a faulty signal to the tach but the signal could be correct going to the rev limiter?

[g21-30]

Mike,

Off hand, I don't remember what the rev limit is; however, a search will probably reveal same. I thought it was like 12,500 RPM. It may be the tach is receiving a bogus signal and the RPMs are really less than the rev limit. When the CDI is bad, the displayed RPMs are higher than the actual RPMs!

[tjkamper]

Weight doesn't effect the actual speed your engine is running. 9k at 70 is about a grand too much. That means the tach is reading wrong. This problem is common with a CDI Malfunction.

[austexjg]

Good thing it still under warranty - I'm considering the GTPP now - should I have this issue repaired ASAP, or wait until the first major service (with GTPP)? How do I convince the dealer that there is indeed an issue?

[Alex]

Just checked out the www.gearingcommander.com site. With stock gearing and stock tires on a 2008+ ninjette, at 9000 RPM in 6th gear the expected road speed is 73.1 mph. Our tachs have a fudge factor, and our speedos certainly have a fudge factor, so I wouldn't be immediately alarmed. It may be reading a little higher (or a little lower) than other bikes, but it doesn't mean there is anything particularly wrong with the bike. There very well may be. , but this data point alone isn't enough to come to that conclusion.

[austexjg]

What other things should I keep an eye out for to help add info. to determine if I have a true problem, or am I just wishing for a 7th gear?

[Alex]

The only likely problem is the CDI issue that seems to affect a number of our bikes. Check the wiki in the troubleshooting section for more detail than you'd ever ask for on the issue. In a nutshell, an overheating CDI causes the tach to do screwy things. Read higher when warm. In some bikes, that is accompanied by running problems as well, while on some bikes the problem seems to be exclusively a display problem on the tach. So if you see different engine speeds on the tach at different times of day, even though you're going the exact same speed on the speedo and are in the same gear, then perhaps you're experiencing the CDI issue.

But it's not likely. The ninjette runs high revs on the highway. With only a small handful of torque, it has to in order to have nearly enough horsepower to push us down the road at highway speeds. It's just the nature of the machine. Some folks do put on a larger sprocket in front to gear the bike a little taller, and lower revs somewhat on the highway, but it's not going to be a night and day difference.

[austexjg]

It does seem to read different RPMs as the heat goes up (guessing without a temp gauge), but the RPMs do seem to differ as the ride progresses. I will check out the wiki, thanks.

[Cedilla]

Ill have to look into this as well, I just figured the tachs were garbage. Can the faulty CDI mess anything else up? My tach as not been reading right since day one, and it otherwise runs fine, the tach being off does not bother me much though.

[Reswob]

Originally Posted by backinthesaddleagain

I find in top gear, stock gearing, stock tires, my revs are about 1,000 more than my speed. 7000 rpm at 60, 8000 rpm at 70.

Same here. For 60, 70, 80, and 90 my tach reads almost exactly 10,000rpm over the speedo.

Originally Posted by Midnightrider

I have run my Ninja up to 14000rpm and the rev limiter has not cut in. I too believe my tach is reading high. Does the rev limiter work off the tach or the cdi unit? Is it possible the cdi unit could be sending a faulty signal to the tach but the signal could be correct going to the rev limiter?

The rev limiter should be between 13.5 and 14 if I remember right.

[CZroe]

I can't believe no one has done this yet...

Link to original page on YouTube.

I hate DBZ so much.

[g21-30]

Originally Posted by austexjg

What other things should I keep an eye out for to help add info. to determine if I have a true problem, or am I just wishing for a 7th gear?

Before I converted my CDI to the '88-94 version, my tach red 7000 RPM at 50, 7500 RPM at 55, ..... when warm. When cold, it read 6000 RPM at 50.

Converted, it ALWAYS reads 6000 RPM at 50, whether hot or cold! The rev limiter is set higher than I want to take it!

Check out the DIY CDI conversion:

http://www.ninjette.org/forums/showthread.php?t=26765

[backinthesaddleagain]

Originally Posted by Alex

Weight doesn't affect what revs show up on the bike at a particular speed. In fact, nothing affects what revs the engine is turning at a particular speed, other than gearing changes. If the passenger causes you to go slower, then sure, the revs would be lower, but only because the speed was lower the same corresponding amount.

My question was mainly the added weight of a passenger would reduce the top end mph, therefore revs would also reduce. So if at 10K rpm solo I am doing 90 mph (speedo indicated), and I add a passenger I would expect to hit 80 mph for example, and revs would be around 9K.

Another way to think of it is riding a single speed bicycle. If my legs spin the crank at 60 rpm and I can go 20 mph, then a passenger gets on the bicycle, the added weight reduces my crank rpm to 30 rpm and my speed drops to 10 mph. Not real numbers but just to make a point.

[CZroe]

Originally Posted by backinthesaddleagain

My question was mainly the added weight of a passenger would reduce the top end mph, therefore revs would also reduce. So if at 10K rpm solo I am doing 90 mph (speedo indicated), and I add a passenger I would expect to hit 80 mph for example, and revs would be around 9K.

Another way to think of it is riding a single speed bicycle. If my legs spin the crank at 60 rpm and I can go 20 mph, then a passenger gets on the bicycle, the added weight reduces my crank rpm to 30 rpm and my speed drops to 10 mph. Not real numbers but just to make a point.

Regardless, the passenger is just a distracting detail. The RPM relates to the speed. Of course the top speed relates to the added load but that doesn't change that relationship any more than manually backing down you speed using the throtlle in the same gear. Not only that, top speed isn't as relevant as RPMs at a given speed.

[backinthesaddleagain]

That is what I am saying revs and mph (assuming same gear) move together. Adding a passenger (weight) puts more load on the engine thus reducing revs and mph. The same is true climbing a hill - revs and mph increase more slowly. Going down a hill revs and mph increase quicker.

[CZroe]

No one's saying you're wrong. It's just clouding things up. Going up hill, you slow down. Going down hill, you speed up. Speed is what is relevant to RPMs... not the hills causing it. That means that they are a distracting/irrelevant detail. Lots of things other than weight or grade can slow you down by sapping power (or speed you up by reducing strain), including headwinds/tailwinds, elevation, etc.

[Reswob]

Originally Posted by backinthesaddleagain

That is what I am saying revs and mph (assuming same gear) move together. Adding a passenger (weight) puts more load on the engine thus reducing revs and mph. The same is true climbing a hill - revs and mph increase more slowly. Going down a hill revs and mph increase quicker.

You answered your own question. Climbing a hill, if you don't downshift, the revs slow, and so does your speed. Engine speed and rear wheel speed are mechanically locked together. 8,000rpm in 6th gear will always be 70mph, etc.

[backinthesaddleagain]

A corner can also cause a change in rpm. As the bike is leaned and the tire is put on edge, the effective diameter changes, thereby changing the effective ratio. Probably not noticeable on the road, unless fully tapped before and through the corner.