My 2008 250r goes 30 MPH at 4000 RPM in top gear, I hear 35 is the typical speed....?

Question

I have noticed when i first start and get going that at 4000 RPM in sixth its around 35 MPH, but then it seems when i keep going it levels out at 30 MPH at 4000 RPM in sixth.

Is something wrong, I am worried i may have power loss to a small degree that could manifest later into something more serious.

Answer 1

the compretion is realy low in your bike to be going that slow.

Answer 2

First your posting does not have enough info.  There are a couple of different bikes that use 250R in their model name.  

Second, the speed of the engine is in a fixed ratio to the  speed of the rear wheel.  If your bike travels at 35 mph at 4000 RPM, when it is cold, then it will always travel at 35 MPH at 4000 RPM.  The only way this could change is if your clutch is slipping and you'd be able to feel that in all gears, not just 6th.

Third, how are you measuring your speed and engine revs?  If you bike has both instruments it sounds like you are riding an EX 250R and that bike runs best at 9000 RPM and higher.  You needn't worry about performance at 4000 RPM because it will be inconsistent at that low of an engine speed.  The slightess hill or wind will effect your speed at that RPM.

If your bike doesn't have both instruments, then how can you tell how it is performing?

Answer 3

My 1972 CT 175 does 60mph at 4500rpm.

If it slows down at 4000 rpm, you have a compression leak in your cylinder head. Get it checked out.