Exhaust valve?

[smasheromalley]

This weekend was my first trail ride on this 85 kx125 I just got.
It seems to be a pretty good bike. VERY light and super easy to throw around. It does lack some power tho especially in sand. Luckily it is also super easy to kick and wants to start readily...

My question I think is going to be on the operation of the exhaust valve. There is a point in the high rmp range where the engine suddenly changes tone and screams to its peak. I find this light switch change to be really annoying. My last bike was a 98 cr125 and remember it being much smoother at delivering hi rpm power.

Ill be on the trail 3rd gear doing berm after berm and right where I want the engine to be then allasudden the engine changes pitch and then Im having to back off the throttle. Is there a way to change the way this valve works? Like I know Im not going to be winning any races with this bike cause I ride with 3 other cr250's, so I dont think I need this type of peaking.

Just looking for ideas, is this phenomenon Im describing the exhaust valve? does it sound like its working properly? If so is there a way to change the way it works?

thanks

-J

[John]

-J,

There are a lot of threads in this forum describing how to change the power band (look in the 500 forums). The engine is slightly different but the technology / fixes are the same. Moose spacer, tweaking the exhaust, change the ignition timing, lower the compression etc.

I found that the Wiseco piston really changed the character of my 125. I suddenly had some power in the lower RPM's.

Alternativly, change to a bigger size machine...

//John

[smasheromalley]

Sure, long term goal is a bigger bike for sure...

Spacer/exhaust mods etc. are in the works. After this past ride I need to get the rear brake right before I start ordering good stuff tho.

I guess its possible I just need some more time on the bike to get used to it. But I was getting around just fine on the bike without that hi rpm snap Im trying to describe.

I like really tight trails and the lightswitch peaking of the engine rpm was annoying. I want it to go away.


*edit* hmm after rereading your post it sounds like you are understanding exactly what I am talking about - I thought you werent. That what I am describing IS just the power band of this engine and that changing/lowering the powerband IS the fix.

Point taken. Ill try to remember to follow up after some changes are made.