2009 kx250f rev limiter bog

my bike starts first kick, every time, runs great until i hop on the track and hit the limiter. it only bogs while I'm on the limiter. it started when put a new oem complete head on it. maybe my jetting could be off, but i dont know what it is. i changed the spark plug, thats about it. maybe yall know what it is. help me out please.

You do know that it's supposed to stop making power when it hits the rev limiter, right?

 

If you are hitting the rev limiter more than once a day, you are going to need to replace your valve train every 25 hours or less.

There is no power up there anyway.

Edited by Krannie

yes, i know, but the bike bogs on the limiter, it sounds weird, it doesn't sound like the regular limiter. 

I have the same problem, it's like the motor Cuts out.

??

The rev limiter is there so that your engine stops before it throws itself out of time and blows up. Since you have taken the engine apart before it is safe to assume that your engine is not keep timed as well as it did when it was new. The tolerance between internals just aren't going to be that good anymore....The engine is cutting out at the rev limiter because it is getting revved to the point that the engine is not in time anymore.   

 

If the bike is "cutting out" power wise at the rev limiter you are revving it to high (past the redline) your lucky it hasn't blown up. 

The rev limiter is there so that your engine stops before it throws itself out of time and blows up. Since you have taken the engine apart before it is safe to assume that your engine is not keep timed as well as it did when it was new. The tolerance between internals just aren't going to be that good anymore....The engine is cutting out at the rev limiter because it is getting revved to the point that the engine is not in time anymore.   

 

If the bike is "cutting out" power wise at the rev limiter you are revving it to high (past the redline) your lucky it hasn't blown up. 

So maybe a new timing chain would fix that? i have a new timing chain that i havent put in yet with the head, so maybe thats it? 

It has nothing to do with the timing chain. The rev limiter simply cuts power to the ignition coil when a certain RPM is reached. Since the spark plug will not spark the engine stops making power until the RPM's drop below the limit and then the spark plug will fire again. When you hold the throttle at that RPM the limiter will cycle on and off keeping the RPM's steady and producing the typical rev limiter sound.

Is the "problem" that you are hitting the limiter sooner than before? If so, that could be a neutral switch problem. If the bike thinks it's in neutral, the limiter is set lower.

KJ's description of what the limiter does is right, of course, and I will add that the limiter is set well after useable power is available and well before you can hurt your bike by over reving it. Hitting the limiter does not damage the motor in any way. That's what it's for. You are most likely to hit it on the starting gate or panic reving over a jump to get the front wheel up. If you are constantly hitting it, you need to shift sooner, because as you have seen, the power drops off considerably just before the limiter kicks in.

What gearing do you have right now?

Is the "problem" that you are hitting the limiter sooner than before? If so, that could be a neutral switch problem. If the bike thinks it's in neutral, the limiter is set lower.

KJ's description of what the limiter does is right, of course, and I will add that the limiter is set well after useable power is available and well before you can hurt your bike by over reving it. Hitting the limiter does not damage the motor in any way. That's what it's for. You are most likely to hit it on the starting gate or panic reving over a jump to get the front wheel up. If you are constantly hitting it, you need to shift sooner, because as you have seen, the power drops off considerably just before the limiter kicks in.

What gearing do you have right now?

it does sound like it is hitting the limiter sooner than before, but there is a bog when i hit it. it doesnt sound normal at all. and im running 13 in the front and 48 in the back

it does sound like it is hitting the limiter sooner than before, but there is a bog when i hit it. it doesnt sound normal at all. and im running 13 in the front and 48 in the back

Can you post a video?

Yes vid please. Also, have you confirmed correct time? Also, what kind of valves do you have and, if SS did you put stiffer springs in?

Your gearing is not the problem. Just the opposite.

Lmfao "if you hit the rev limiter more than once a day you will have to replace valve train in 25 hours or less"

Yeah okay good one lol!!!!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now