Redline

[bleys]

Some various musings about CVT scooters and tachometers.  My Xciting 250 has a tach and it redlines at 7500 rpm.  This limits my upper speed to around 72 mph.  I do not exceed redline, yet on the interstate, I could use a little more speed.  The scoot still has plenty of throttle at redline and I also know many scooters have no tach and are ridden WOT all the time with little seeming harm to the scooter.  So why a tach on a CVT? Is the redline for real?  Am I just being stupid about this?  I know it is a different engine but the Ninja 250 revs about 10,000 consistently, with a upper limit of 14000.  So any feedback on this would be welcome guys.  Thanks.

[bleys]

To add....I don't expect anyone to recommend going over the redline limit...just wondering why it is there and why 7500 rpm....I know earlier models of the Xciting 250 redlined at 8000 rpm for instance.  And again why put a tach on some scooters and not others?

[MotoRandy123]

On very high revving bikes the motor can be damaged if you overrev too much.
Most have a limiter in the ignition circuit to stop you from damaging the motor.

Some bikes will limit themselves via valve float. Above a certain rpm the valves
won't close so the power will fall off. I believe most scooters are in this category.
My Yager redlines at 8000 but I've seen 9000 when it was accidentally tuned wrong.

On an interference motor the valves will hit the piston if they float. The force imparted
to the rod goes up fast with higher RPM's. You usually figure piston speed and there is
a limit to how much force the rod can handle before it lets go (and parts come out the side
of the motor.

We don't have much info on our scoots as to the RPM at which damage will occur so if you
exceed the redline you do so at your own risk. I would assume there is some buffer built in.
My tach shows 8000 - 10000 as red. Whether there is or isn't a tach is based on cost or looks
mostly so is at the whim of the manufacturer...
 

[streido]

The CDI on my A50 was limited to around 7500rpm too before i cut it, now revs to 9000rpm or just over downhills at WOT, been running it like this for over 2 years now with no damage to the engine at all. I didnt have a tach but fitted one to help with tuning a while back. I ride WOT all the time when i ride it, normally never drops less than 6500-7000rpm, only minor issue is that running it at higher rpm's is the belt and rollers wear out a lot quicker so need replaced more often.

[ophelia]

Are you banging off a real rev limiter at 7500 rpm?

I thought my Bet and Win 250 redlines higher. I forget what it is (8200-9000 rpm?), but I thought I have gone past 7500 rpm on the indicator. Check your roller weights and belt for wear, in case they aren't allowing you to hit the top gear ratio on the freeway.

Or maybe your Xciting is quite a bit heavier and harder to bring up to top speed.

[bleys]

Thanks for the feedback guys...along the lines that I was thinking as well.  And to Surgeon...no it is not a rev limiter at 7500...I've had it over 8000 -rpms on a couple of occasions when accelerating and it still has throttle left.  The Xciting is heavier than the Bet & Win (407 lbs - dry wt.)  but still responds well to throttle at redline.  I just try to not go over for concern of causing damage to the engine. 

[ophelia]

If you keep up your oil changes, you should be just fine at high rpm.

[Vivo]

A Tachometer looks good on any vehicle... that's the reason it's there... my two cents...