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32mm carb

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Have anyone fitted a 32mm FCR carb of a CRF 150, onto a 250X ?
thinking of trying this to create a trail/trial beast.
11t front and 53 rear gearing,
thinking of a flywheel weight as well.

comments please.

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A heavy flywheel makes a very notable difference, 

over winter I switched from a steep 13/53 to 13/51 but added a +12oz Steahly 

despite the gearing change the engine is much more tractable at low rpms and now pretty much stall proof.


* went to 13/51 only to make 1st gear a bit more usable


14/53 :   3.79:1  (stock)

13/51 :   3.92:1

13/53 :   4.08:1


Anything under a 13T front will put extra stress on the chain but something you'll have to live with to get the wanted final drive ratio.

I've also seen 54T rear sprockets advertised, maybe even a 55, but have read that even the stock 53 is pushing the limits of the chain guide.

Edited by mlatour
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First off you'll never make a CRF250X a trail/trial beast because it is too big and heavy, however it can be modded to better suit your riding terrain.  I've done some mods to my X to make it better suited for some of the trails that I ride, and your needs may be completely different. For the really gnary stuff I ride a different bike.  My X is plated for road so it is geared higher than others (14/51 = 3.643), and I've used (14/48 = 3.428). I usually  trail ride mostly in second, and I modded the clutch for less lever pull and use it a lot when in 1st gear. 

  • Get the heaviest flywheel you can find, it will transform the engine for slow work.
  • Keep stock jetting for a softer low speed throttle response, CCC mods and jetting for more aggressive throttle response
  • Unplug the Throttle Position Sensor (TPS) for low traction situations, keep for more aggressive throttle response.
  • Keep the stock muffler and header, R header for slightly less bottom end torque.
  • Consider using the milder CA camshaft for more bottom end, or R cam for less bottom end torque.
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