Engine RPM redline?

[sailorcolin]

I have a Trail Tech and I want to set up the shift point light and red line light. What should be a good red line RPM to set it at?

[rbates9]

I wouldn't bother with the shift point light because it will all depend on what and how your riding. If your coming up to a steep hill your shift point will probably be much different then cruising down the access roads.

And the red line will be when the engine stops revving up any more. You could probably set the shift light at that point also.

[KDXohio]

you can set your redline a hundred rpm or so before it completely tops out

[sailorcolin]

you can set your redline a hundred rpm or so before it completely tops out

around what numbers are those? i am a lil afraid of taking it all the way but ive never really had a powerfull 2smoker just lil mopeds

[Thrahl]

For the E series bikes the manual says they make max horsepower at 7500 rpm and max torque at 7000 rpm.
I don't know at what RPM they stop revving generally, but I would probably set my shift light to around 7500.

[Jaguar]

The absolute max RPM mostly depends on piston speed which can be calculated at http://www.csgnetwork.com/pistonspeedcalc.html
The idea is to not let that speed go more than 4000fpm for sustained periods.
The KDX 200 has a 58mm stroke which is needed to know to use that calculator which sets the RPM limit for the KDX at 10,500.
I know all of you are saying that no KDX goes up that high. That is because the CDI sets the limit by retarding the ignition timing too much past 9000 (I think that RPM is right but don't quote me). If you port the engine for high RPM it still won't get up to 10,000 because of the CDI. The KDX CDI I make has an adjustable timing curve that allows more RPM. This of course should be of great interest to anyone wanting the maximum performance from their ride. Keep in mind that expansion chamber dimensions also set the maximum RPM. If the CDI is changed to allow more RPM, and the cylinder porting is right for higher RPM, then the only limiting factor is the pipe. In that case you need to shorten the header. Shortening it by 3.5" allows 1000 more RPM.

But the main idea of reline is to alert the rider of when the engine is turning so fast that it may be damaged if that RPM is sustained. Normal KDXs don't need a redline because the pipe and the CDI keep the engine from dangerous RPM.