more trail friendly crf250r

Hey guys, this is my first post. So I just picked up a 2005 crf 250r and I absolutely love it. The only problem I have with it is that it is not trail friendly at all. First gear no throttle it is pretty fast. And on top of that it stalls if I turn the idle down and. So I checked my sprocket set up and I have 13 teath on the front and 52 in the back. I just wanted to ask if anyone has done any good mods to make a race bike more trail friendly. Also those rekluse Z starts are way to expensive.
 

SRAD97750

Moderator
Staff member
I think you would do well to change the sprockets to match the trail type you wish to ride.
In your case, I would try a 12t front sprocket and see if the top speed is too restricted for what you're after. If it is, you may want to try smaller changes by increasing teeth on the rear.
-BIG DAN:thumb:

Changes in sprocket size can do many wonderful things and fine tune how the bike puts the power to the ground.
Changing the rear sprocket more directly affects top speed in each gear.
Changing the front sprocket is more dramatic and actually changes the characteristics of how the bike makes power, due to inertia.

You can get nearly the same final drive ratio by changing the front OR rear sprocket, but how you want it to "change" determines which sprocket to alter.

Example.
15X50 is 3.33
and
16X53 is 3.31
They are very similar ratios, but have dramatically different effects on the bike.

The 15 tooth front sprocket will be easier to turn because it has fewer teeth (distance) per revolution.
The 16 tooth must pull the extra distance in the same revolution. (Mathematically requiring more power to do the "work.")

Even though these "distances" are nearly equaled by the rear sprocket size, the inertial effects are greater at the engine sprocket.

I would expect a 15x50 to "rev" faster than the 16x53 setup.
Alternatively, this 16X53 can be used to smooth the hit of the engine, just like a flywheel weight. But the weight is at the counter shaft.

Trial and error for every bike is different.
-BIG DAN:thumb:
 
Hey guys, this is my first post. So I just picked up a 2005 crf 250r and I absolutely love it. The only problem I have with it is that it is not trail friendly at all. First gear no throttle it is pretty fast. And on top of that it stalls if I turn the idle down and. So I checked my sprocket set up and I have 13 teath on the front and 52 in the back. I just wanted to ask if anyone has done any good mods to make a race bike more trail friendly. Also those rekluse Z starts are way to expensive.

A cheap mod would be to add a flywheel weight, this may allow you to run a lower idle speed and not stall the motor, it will also make the power a little more manageable in the slow tight trails.
 
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