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06 CR250R advice


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Hey all, so it looks like I am going to be purchasing a 2006 CR250 this coming weekend. I am pretty excited because the bike is really clean, all stock and a good price.

After reading a lot of TT posts on the 05-07 CR250's it seems the biggest complaint about these year bikes was the bottom end power.

I would like to get some input from you CR250 experts out there on what I can do to get a little better bottom end power out of this bike without performing any major engine work.

Most of my riding will be in the woods with the occasional trip to the sand dunes at the coast. I thought I would throw that out there.

All comments are appreciated

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I don't feel the stock 05-07's lack lowend power.  IMHO they need the cyl. head squish reshaped to achieve better jetting & think that is the only flaw.  With the squish band corrected & optimal jetting you can achieve a smoother low-mid transition that won't feel as abrupt.  Look into RB designs if you plan on going this route as I've seen very good feedback on his work.   Installing a Keihin PWK carb would also be a good option, but don't feel it's necessary.         

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My 06 in stock form had little to no bottom end, a monster mid range hit that hit unpredictably at times and a quick sign off on the top end.  If you were an expert MX rider and could keep the bike in the mid range all the time, it would probably be perfect.  I took the advice of CamP on this site and had the base of the cylinder shaved by .030, and had the head cut for pump premium fuel and along with a keihin PWK from a 00 and up YZ250, IMO the bike is perfect now, no need for reeds, pipes or anything else.  The bike is perfect, has TONS of low end now and never seems to sign off on the top end.  I recently let my cousin who rides a "legendary" 08 CRF450r ride it and he could not stop raving about how much power it had.  Here is the link to CamPs build thread on his 07 cr250:

 

https://thumpertalk.com/topic/941288-new-07-cr250/

 

That thread is a long read but worth it.  The machine work from Eric Gorr cost me $119 shipped and was worth every penny. 

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I know I'm a broken record with this, but have .030" milled off the base of the cylinder. If you run race gas, leave the head stock. If you run pump gas, have the head milled to lower the compression.

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Ride the bike first before doing anything, if the jetting is good on it then maybe an FMF Gnarly pipe for the woods but other than that you will probably find I more than adequate.  I have the "slouch/worst year" 2002 and It has plenty of bottom for the woods even for my fat a$$

I have ridden an 07 with a Gnarly & it does smooth out the mid range hit.  The pipe is better suited for woods type of riding & does give the motor a torque feel from low-mid, but will sacrifice some topend.  For money well spent the head work would be more cost effective vs. the pipe unless you can find a good deal on a decent used one.   

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My 05 was a stock motor and I put the Vforce 3's and a fatty pipe. It did help to massage the hit and wake up the low end, but it still always required 50/50 with race fuel. I just picked up my 07, and Eric has the cylinder for the cut and head squish mods even before I rode the bike. It came with a gnarly pipe and a boyesen rad valve, so I will try it that way and see how it goes. It will be studded up for some ice riding before next season, which will draw every bit of torque it will make..

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Thank you all for the advice! It sounds like the consensus is... head work is the best way to go for the money to get better low end. I am not much of a mechanic so maybe this is a dumb question, but if I got the head work done, would I need to change anything else on the bike when putting it back together? Like a new piston or other engine components?

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Thank you all for the advice! It sounds like the consensus is... head work is the best way to go for the money to get better low end. I am not much of a mechanic so maybe this is a dumb question, but if I got the head work done, would I need to change anything else on the bike when putting it back together? Like a new piston or other engine components?

 

Best bang for the buck is getting cylinder and head work done.  getting the cylinder shaved changes port timing and adds a ton of low end but does not take away from the top end at all.  Like I posted above, getting the cylinder shaved and head cut for whatever fuel you want to run cost $100 plus shipping if you have Eric Gorr do it.  Not sure how much RB Designs would charge for the same work.

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Thank you all for the advice! It sounds like the consensus is... head work is the best way to go for the money to get better low end. I am not much of a mechanic so maybe this is a dumb question, but if I got the head work done, would I need to change anything else on the bike when putting it back together? Like a new piston or other engine components?

I'd suggest calling this guy to discuss head modification options.  http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&sqi=2&ved=0CB4QFjAA&url=http%3A%2F%2Fwww.rb-designs.com%2F&ei=5DSuVJe3OYnVoAS6tYCQAQ&usg=AFQjCNEUV8Y3grL8bhrLR7BC8K99cNz0UA&bvm=bv.83339334,d.cGU

As far as changing components the piston would be a good idea to swap since it will be a used bike & you can start off with a fresh topend.  I'd highly recommend getting a Honda service manual & read up on it.

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I'd suggest calling this guy to discuss head modification options.  http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&sqi=2&ved=0CB4QFjAA&url=http%3A%2F%2Fwww.rb-designs.com%2F&ei=5DSuVJe3OYnVoAS6tYCQAQ&usg=AFQjCNEUV8Y3grL8bhrLR7BC8K99cNz0UA&bvm=bv.83339334,d.cGU

As far as changing components the piston would be a good idea to swap since it will be a used bike & you can start off with a fresh topend.  I'd highly recommend getting a Honda service manual & read up on it.

 

Thanks H4L, I will check R&B out.

Best bang for the buck is getting cylinder and head work done.  getting the cylinder shaved changes port timing and adds a ton of low end but does not take away from the top end at all.  Like I posted above, getting the cylinder shaved and head cut for whatever fuel you want to run cost $100 plus shipping if you have Eric Gorr do it.  Not sure how much RB Designs would charge for the same work.

 

Thanks FRDBTR, I am going to call both Eric Gore and R&B and compare prices.  I appreciate the help and advice from you and everyone!

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