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03 cr250 performance gains?

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What can anyone recommend to help my bike(03 CR250r) climb like a KTM 300 XC?  I know what most of you will probably say and that would be to go buy a 300 but that is not in the cards right now as I can't afford another payment right now.  The mods that are currently on my bike are FMF gnarly pipe and VF3 reeds, a JD jet kit in it and 13/50 sprockets. It runs good but it won't climb some of the hills the 300 will and I have ridden the 300 and it makes climbing a breeze.  I was tempted to try a flywheel weight but I have never tried one so any help I would appreciate.  I'm 220lb rider by the way.

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How's your suspension setup?

(14 year old bike, have the forks/shock ever been refurbished?)

 

Stiff MX suspension settings simply don't work for trail / off-roading,

if the chassis can't put the power to the ground without breaking traction / wheelspin, having even more power on tap is useless.

 

Just like motocross and any other off-road bike discipline, having the correct spring rates &

valving for your: weight, riding skills and specific application, will net you more gains than adding yet more engine mods.

 

Making sure your engine is fresh (compression) and tuned / jetted to perform it's best

you already seem to have the best pipe for added low end grunt.

No doubt a heavier flywheel helps quite a lot for better tractability.

Edited by mlatour
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2 hours ago, mlatour said:

How's your suspension setup?

(14 year old bike, have the forks/shock ever been refurbished?)

 

Stiff MX suspension settings simply don't work for trail / off-roading,

if the chassis can't put the power to the ground without breaking traction / wheelspin, having even more power on tap is useless.

 

Just like motocross and any other off-road bike discipline, having the correct spring rates &

valving for your: weight, riding skills and specific application, will net you more gains than adding yet more engine mods.

 

Making sure your engine is fresh (compression) and tuned / jetted to perform it's best

you already seem to have the best pipe for added low end grunt.

No doubt a heavier flywheel helps quite a lot for better tractability.

I just put new rings in the top end on Friday.  I had the front forks and rear shock revalved and respringed for my weight and riding style.  It is just a fun bike in general but getting my butt handed to me on a 400 ft climb where the rest of the fellers are making it up kind of sucks.  I would hate to give up on this bike since it is just an all out blast its just those damn hills LOL

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Even on a engine that's already pretty tame, a 12oz heavier complete flywheel assy. really transformed my CRF250X,

it increased tractability quite a bit in difficult situations.  No doubt it would help in your application as well.

 

Comparatively, an added-on flywheel weight (7oz) is barely noticeable on my track ridden YZ125.

 

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A Boyesen Rad valve has modest gains in the low-mid vs. the V-Force that helps the mid-top.   Shaving the head .010" to increase comp. will also help in the low-mid part of the powerband.  A heavier flywheel will help with traction if your riding steep hills.    

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6 hours ago, H4L said:

A Boyesen Rad valve has modest gains in the low-mid vs. the V-Force that helps the mid-top.   Shaving the head .010" to increase comp. will also help in the low-mid part of the powerband.  A heavier flywheel will help with traction if your riding steep hills.    

I did put a thinner cometic base gasket in.  If I have the head shaved will that be too much with with base gasket I'm using?

Edited by cerialsledder

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1 hour ago, cerialsledder said:

I did put a thinner cometic base gasket in.  If I have the head shaved will that be too much with with base gasket I'm using?

You can measure the squishband to see where your at.   http://www.rb-designs.com/rb_designs_llc_017.htm

I'd also suggest contacting Ron at RB Designs & discussing with him what your trying to accomplish with the engine.  He has a very good reputation on this site with good mods to the head.

Check your comp. to see where the engine is at with the thinner base gasket.  That will also give you a good indicator & can safely run premium pump fuel into about the 205-210 psi range.  

Edited by H4L

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11 minutes ago, H4L said:

You can measure the squishband to see where your at.   http://www.rb-designs.com/rb_designs_llc_017.htm

I'd also suggest contacting Ron at RB Designs & discussing with him what your trying to accomplish with the engine.  He has a very good reputation on this site with good mods to the head.

Check your comp. to see where the engine is at with the thinner base gasket.  That will also give you a good indicator & can safely run premium pump fuel into about the 205-210 psi range.  

Engine compression is at 205psi right now.  I am mixing 50/50 of 110 and 91 non eth premium now.  Rather be safe than sorry with the high grade of gas we buy at the pumps anymore 

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8 minutes ago, cerialsledder said:

Engine compression is at 205psi right now.  I am mixing 50/50 of 110 and 91 non eth premium now.  Rather be safe than sorry with the high grade of gas we buy at the pumps anymore 

True.  If your running a 50/50 mix already you should be good.  I'm running about a .035" squishband on an 03 engine, but running VP C12.  Most tuners will run a safe # between .045" - .050" for a weekend rider. 

Locally to me I have a 76 gas station that I can still buy premium 100 octane at the pump that would safely run on an engine with a 210 psi range. 

Edited by H4L
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22 hours ago, cerialsledder said:

What can anyone recommend to help my bike(03 CR250r) climb like a KTM 300 XC?  I know what most of you will probably say and that would be to go buy a 300 but that is not in the cards right now as I can't afford another payment right now.  The mods that are currently on my bike are FMF gnarly pipe and VF3 reeds, a JD jet kit in it and 13/50 sprockets. It runs good but it won't climb some of the hills the 300 will and I have ridden the 300 and it makes climbing a breeze.  I was tempted to try a flywheel weight but I have never tried one so any help I would appreciate.  I'm 220lb rider by the way.

What problems are you having with climbing?  In the bottom part of the power?  Wheel spin?  Is the engine bogging?  If you give more info about what type of climbing you are doing I could probably help more.

I don't feel I'm missing anything to a 300 right now but I have extensive modifications to my 03.  The biggest power changers for me have been the STIC metering block in a Keihin PWK carb and a full Varner built engine.  Every other mod pales in comparison.  I also run the stock pipe with a PC silencer, 8oz FWW and VForce reeds.  I am running stock 13/48 gearing and I can pull any hill that my buddy's 300 can pull.   

I previously went the big bore route and even tried the gnarly pipe.  I didn't like the power delivery at all with that setup.

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8 minutes ago, c-slak said:

What problems are you having with climbing?  In the bottom part of the power?  Wheel spin?  Is the engine bogging?  If you give more info about what type of climbing you are doing I could probably help more.

I don't feel I'm missing anything to a 300 right now but I have extensive modifications to my 03.  The biggest power changers for me have been the STIC metering block in a Keihin PWK carb and a full Varner built engine.  Every other mod pales in comparison.  I also run the stock pipe with a PC silencer, 8oz FWW and VForce reeds.  I am running stock 13/48 gearing and I can pull any hill that my buddy's 300 can pull.   

I previously went the big bore route and even tried the gnarly pipe.  I didn't like the power delivery at all with that setup.

The one climb I am having a hard time doing right now is a 400 foot long climb in a bit of sand.  I get 80% up and she just runs out of motor is all and by the time I down shift to 2nd I really have to work at it to get it moving again.  I can post a link to a youtube video of me  climbing it if you want.  Give me a few 

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At some point a 250 is a 250 no matter the tune. 400ft with sand is a real test, maybe you bought the wrong bike for that particular need. Physics is real.

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Just now, YHGEORGE said:

At some point a 250 is a 250 no matter the tune. 400ft with sand is a real test, maybe you bought the wrong bike for that particular need. Physics is real.

when I bought the bike I originally was going to just do single tracks and do an enduro or two but then I got into doing some of these climbs and it really gets my heart going when I'm doing it

 

 

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29 minutes ago, YHGEORGE said:

At some point a 250 is a 250 no matter the tune. 400ft with sand is a real test, maybe you bought the wrong bike for that particular need. Physics is real.

Here is a link to the video of the hill I was trying to climb.  

 

 

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47 minutes ago, cerialsledder said:

Here is a link to the video of the hill I was trying to climb.  

 

 

Instead of trying to grab second at the end I would say feather the clutch to keep it up in the power.  Not sure if that would work though since you are dealing with what looks to be the steepest part of the climb at the very end.  Consider yourself lucky, In AZ all of our hill climbs either have rocks everywhere, or are dunes/volcanic cinders.  

If you really want to throw money at the bike the first thing I would recommend is ditching the Gnarly.  Either go back to stock or go with a HGS pipe.  That is a max HP type of hill climb and the Gnarly neuters the peak HP on any bike.  

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4 minutes ago, c-slak said:

Instead of trying to grab second at the end I would say feather the clutch to keep it up in the power.  Not sure if that would work though since you are dealing with what looks to be the steepest part of the climb at the very end.  Consider yourself lucky, In AZ all of our hill climbs either have rocks everywhere, or are dunes/volcanic cinders.  

If you really want to throw money at the bike the first thing I would recommend is ditching the Gnarly.  Either go back to stock or go with a HGS pipe.  That is a max HP type of hill climb and the Gnarly neuters the peak HP on any bike.  

That's why I was wondering if a flywheel weight would help that?  I no longer have the stock pipe as I sold it to get some parts for my sled :)

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