Honda Dirt Bikes Forum

i just purchased a 2001 CR 125,its completely stock and im wondering what i can do to improve its performance? what aftermarket pipe adds the most hp? are aftermarket reeds worth the money? any info would be great.  

well no pipes or reeds will add hp. all they do is move the powerband and how and where the power is delivery. i dont think either are worth it. after market reeds will mostly give you better throttle responce, but it might not even notice it, but they will wear quicker. now aftermarket pipes i suggest keep the stock one, unless its dinged up or you just want a more factory look. because aftermarket pipes look way better.

if you really want to get more out of it, then spend money on getting the suspension rebuilt and set up for you, with either a revalving or spring change. a good suspension will do way more for you then engine mods.

but if the engine is feeling weak then its probably time for a rebuild. but if the top end is good then it probably needs jetted correctly, it is a honda which are known for bad jetting, correct jetting will also give you better throttle responce. or some other stuff you can do if both of them are good is a big bore kit, or port and polish.  
______________________________
Ride 2 strokes, buy 2 strokes, save the 2 stroke.

1998 cr125
2002 cr80

yeah the pipe is dinged up a bit and i will be doing a topend rebuild this winter.i may sharpen the transfer ports while its apart.i do mostly woods riding so i'd probley want alittle more torque in the lower rpm range.the pro circut pipe looks pretty sharp. My buddy has a 94 KDX 200 so i am hoping to be ahead of him.  

you need to worry about him. your bike stock will blow him away. but it is 95% rider and 5% bike so if he beats you then its you and not the bikes fault. but the pc platinum pipe is really nice, i have the works pipe with the 304 silencer.  
______________________________
Ride 2 strokes, buy 2 strokes, save the 2 stroke.

1998 cr125
2002 cr80

did you have to re-jet for the pipe? my bike seems alittle Fat at high RPMs i was going to adjust the air screw to see if it made it a bit better.  

yes. i bought my bike last year with stock jetting and had to completely redo the jetting. it took me a whole year to get the jetting right on it, i just got it dialed in a few weeks ago. i doubt you will have as much trouble as i did. its not really about the rpm's, it matters on the throttle position. the air screw only adjusts from idle to 1/4 thottle. if your bogging at full throttle then your main jet is rich. if you get an aftermarket pipe then you will almost certainly have to put a leaner main jet in.  
______________________________
Ride 2 strokes, buy 2 strokes, save the 2 stroke.

1998 cr125
2002 cr80

so a aftermaket pipe will make it richer? i would have thought otherwise..but thats no problem.i guess it all comes down to plug colour in the end.what did you settle on for a main jet in the end? i know mine may be different i am at sea level as far as alttitude goes.  

well i changed the stock plug from a br9eg to a br8eg, which is hotter. because i kept fouling plugs on trails but it ran fine on the track. stock main jet is a 172 and in the summer in pittsurgh, so about 90's degree and around 1000 feet i ended up at a 168. in the winter, about 30 degrees i will have to run probably a 172. stock pilot jet is a 52 and in the summers i have to use a 48. and in the winter i will probably run a 52 or 55.

after all this work with my carb, i have become pretty good with jetting and can help you get yours fixed. you can even ask some of the other jetting masters on the site. aka skip, and woods.

your jetting will be completely different. i have a keihin carb and you have a mikuni carb. your main jet should be like 320 or something like that.  
______________________________
Ride 2 strokes, buy 2 strokes, save the 2 stroke.

1998 cr125
2002 cr80

ahh i wondering about the 172..lol
im gonna do a wide open run and check plug colour that should tell me more as far as jetting goes.
Thanks for the help its been 10 years sence i've run a motorcross bike.  

You could buy the Eric Gorr performance book for 01 CR125. It will tell you how to modify the transfer port.  
+++++++++++++++++++++

I love the Turtle Posse!