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What's the best 2004 CR250R mods?

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Depends on what you're using the bike for. MX, woods etc

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Start with a PWK from a YZ, or RM, with a TPS adapter harness.  There are many jetting options.  Then maybe consider some Cylinder and head work.  There are some pretty good tuning options as well.

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There are enough topics in the Honda 2stroke section which will give you an answer to that question...

But:

PWK38 Keihin carb with nr 7 slide and a N3CW Yamaha needle (jetting depends on place you ride), OEM exhaust, 05-07 basegasket or shave bottom cylinder 0.03 and mod head accordingly do not exceed 220 psi head pressure, some CF reeds to keep things crisp and safe, check if the power valve operates correctly.

Done ;)

Or did I forgot something....

Edited by Daniello
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What about suspension valving anyone had any luck getting them plush without bottoming.

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What about suspension valving anyone had any luck getting them plush without bottoming.

Suspension would be my #1 option on mods.  We are fortunate to have some good tuners here in CA that can get you those results like FC. 

Tuning the carb or swapping to the popular Keihin PWK mod would be 2nd on the list.  The rest is icing on the cake with engine mods (port work / head mod) on the 3rd gen 02-07 models.     

Edited by H4L
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There are enough topics in the Honda 2stroke section which will give you an answer to that question...

But:

PWK38 Keihin carb with nr 7 slide and a N3CW Yamaha needle (jetting depends on place you ride), OEM exhaust, 05-07 basegasket or shave bottom cylinder 0.03 and mod head accordingly do not exceed 220 psi head pressure, some CF reeds to keep things crisp and safe, check if the power valve operates correctly.

Done ;)

Or did I forgot something....

 

I'm having better results with a #8 notched slide from a 2000 KX pwk.  Jetted with the N3CW 3rd clip, 45, 175.  

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Yes I agree. I did the MxBonz air box fix to both my CR's (05 144, 06 250).

is it a bigger air box? Where do I find one?

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I'm having better results with a #8 notched slide from a 2000 KX pwk. Jetted with the N3CW 3rd clip, 45, 175.

I had a nr8 slide in as well, thought the 7 was better (meant that I read that somewhere here on the forum).

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I had a nr8 slide in as well, thought the 7 was better (meant that I read that somewhere here on the forum).

 

I think the #7 is the most common slide used in the pwk, so it would be the starting point for most pwk conversions.  For 125's the #5.5 slide from 99 CR250 works better.  I use a #6 for my 144 in conjunction with alternate 2000 CR250 needle A685/294R.  For 250's the #7 is good, and the #8 is probably better for cleaner low end woods applications.

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First thing air box mod.

Good call.  I guess it's still possible 10 years later there are some 04 models that haven't had it done.

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Good call.  I guess it's still possible 10 years later there are some 04 models that haven't had it done.

 

Haha yeah I still see quite a few 3rd gen CRs on CL that don't have this mod. Blinged out to the T but most likely sucking in dirt. Thank goodness for forums like Thumpertalk to spread the info. With out this site my bike wouldn't be half as awesome as it rides now. 

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The air box mod is good, but it isn't really necessary. As long as you seal the boot/box junction with super weatherstrip adhesive and grease the rim of the filter, you won't have a problem.

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