For you cr125 guys or just 125 guys

My friend owned one from brand new best mod ever did was the pwk swap.

Owned it for 15 years 

Pipes didn't do a whole lot rad over vforce. 

Eric gorr did his 139/140 big bore on it with more mid top style porting. Higher compression head. Really ripped after that lot easier to ride. 

My friend who owned it raced it in 50+ and 60+ expert. Sometime in 14 put the engine into a 2010 crf250r chassis. 

A few years back put it back to the stock 125 top end. After one ride back to the 140. To bad Eric gorr is retiring from doing big bores this year. Best $600 spent on it. 

If it were me I would spend my time dialing in the suspension with basic oil, springs and clickers, and spend my budget on the motor.

You can do fat boy mountain bike tubes and Hoosier tires to shed some weight over stock tubes and heavier tires.

PWK, JD jet kit and a Rad Valve along with a pipe and silencer. 
I added a tooth to the rear as well to help pull my 190# ass around. Was a shit ton of fun and can honestly say I miss it. Sold it a couple months ago. 

Have Fun!

Good find and congrats on the new to you scoot. I did something similar a bit ago with an 07'. Went Vforce3 as it was more available at the time, threw the PC jetting specs in it, run 50/50 Sunoco 110 Leaded/pump at 32:1, and went with a 53T rear sprocket...Great bike that's extremely well-built, quality wise, and FUN to ride. 2005-2007's were much improved over the 2002-2004 iterations and parts are still available. Only real handicap against 125's of the era was the 5-speed transmission; simply takes some getting used to and first gear is a necessity at many tracks. In addition to your current plans, a 270mm front rotor kit is also a wise investment - Stops on a dime and much improved over the 240mm stocker. The Twin Air filters are also a good buy as they have a thicker sealing lip (replacing the airbox gasket should also be towards the top of your to-do list: PN 17219-KZ3-J51).

https://www.dirtrider.com/tests/motocross-bikes/141_0502_2005_honda_cr1…

https://motocrossactionmag.com/on-the-record-complete-test-of-the-2005-…

Please don’t restyle it. Keep the plastics stock, looks way better. Suspension and a top end plus the bars of your choice and let it rip

These bikes are a lot better out of the box than most people would have you believe, it's not going to be a YZ or a KTM motor-wise no matter what you do but they handle great and the suspension is really good right out of the box.  

I haven't seen it mentioned but the filter sealing surface of the airbox on these bikes leaks and will let dust in, before you ride it I would highly recommend getting the MX Bonz kit or just making your own like I did.  I also did the Keihin carb swap and that really made a massive difference on this bike, I would recommend that over a pipe and silencer if a choice had to be made.  Running 50/50 race gas may not be a bad idea either, my 04 tends to detonate a bit on 91 so if I can bump it up to around 94/95 octane it seems to help.  Aside from that rip it an have fun, they're great bikes if you're looking to have fun and don't care about trying to compete with the Austrian machines.  

i had an 07 a while ago that was an awesome bike. Suspension and bars and a few little cheap mods and you got a great bike.

Boysen Power wing is such a cheap and effective after market part id highly suggest. makes a huge difference with the CR's Power feel and a billet throttle tube is another great part that you'll surprising notice.

i had full works PC exhaust and end up switching back to the stock pipe with a PC shorty on the rear. More top end made it feel a little easier to keep momentum i felt. 

I sent you a bunch of bolt on tips in your other thread. I mentioned the 03 kx125 pipe the cone is massive. On the 06 it had great snap off idle then a quick hit with a lot more mid & torque with 1 ,200 + rpm it still pulled up there. That pipe on the 04 was Really slow to hit but when it did it was Very strong mid to 1,500 + rpm kept pulling.  Twin air power flow alum cage improves throttle response & gets on the pipe quicker, mid-top is improved a little.the filter is smaller stock ta filter won’t work.  Bike runs cleaner. V force the bike runs great but you don’t feel a torque improvement like the rad valve.  IKat improves throttle response will chatter the rear wheel threw the mid. IKat is not made anymore so there difficult to find. A toggle switch ignition is available in Europe. Grind the mounts to bare alum for the coil. Or buy a new coil the cr is noticeable snapperier. Boyeseen carbon reeds with stock cage r in my 04 practice bike with stock pipe & pc shorty. Pc reg silencer isn’t as quick getting on the pipe. it runs stronger than my 05. Boyeseen sells carbon tech reeds . I haven’t tested them in my cr,s but they worked great on rm,s.  I went to stiffer for& shock springs ,added fork oil comp on 1 out. I used mxa updated clicker spec except for comp. Still play with clickers a little.  Very plush suspension .  3+ ft clay whoops the forks where too soft. FC revalve for 3.5 ft whoops was much stiffer.  I had 2 06,s & a mod 04 stroker stolen. I hv 2 04,s & a 05 I,m probably gonna sell.  No pc alum throttle tube is avail but answer t tube is pretty good.  A little stab of the clutch & it hits 06 is equal to a 06 yz except for finicky jetting. But they handle soo good, super fun to ride. Plz don’t upgrade the plastic that looks horrible & make the bike feel weird.  05-07 rear hub is lighter & a work of art like the whole bike. Shaft for the pv flaps scotch bright  a little & Polish the round part that touches the cylinder. Pv will operate easier& smoother. I would like to try a hgs or Messico pipe you can run a pc silencer with them also. Stock piston is really cheap 59.00 . Racer choice is the best . The gp is very durable. 03 kx pipe I had to pound a dent to clear the kick starter & a radiator hose on a 04 that a 05-07 doesn’t hv. Bend the stinger cut a little off & cut some off the silencer& make a bracket for pipe- silencer connection. It was pretty easy to do. 

The biggest thing with these is getting more air to the airbox. I would think about cutting holes and opening up that area.

3 holes made a difference.  Any small change you feel a difference.  You could jet twice a day in a humid state.  But once you figure out morning to late afternoon jetting. I think the stock reeds flutter . 

https://youtu.be/4iEdDytXj4shttps://youtu.be/4iEdDytXj4s

Not me, my son Shaun 

04 FMF pipe and bud racing silencer  boyesen pro reeds VP T2

 Pipe, muffler, vforce and a 53t rear sprocket and they’re decent 🤌

I’m just cracking up at this guy calling FC and saying he needs a revalve for 3.5 ft whoops instead of 3 😂😂😂

It sounds like a 04 only 1 bike has that mid sound. But what is a fifth pipe ? Great riding & shifting on the mid.  I,m so happy & shocked by how great my practice 04 runs. I switched cdi,s to the stock 5 hr bike to see if the cdi,s where diff. After 12 yrs off a bike I had no trouble pulling 23 yz& Ktm out of corners into a steep hills. Time the hit perfectly & the bike is hard to beat. Same corner & speed you get a diff hit& pull. It makes riding so fun. Watch - old video LTM 2004 cr125 great example.   My JM racing engine is not together it’s still winter here.  If you want a quick & reliable strong running cr125   John is the man he probably did 5,000 of them. 

Fmf reg silencer is the worst. Best is the short pc. Reg pc is good but doesn’t hit as quick.  I tested those. Bud shorty might be good. Hgs pipes are always good . Messico I,m sure is great to. 

I'm a 30+ vet guy and this is my first time owning a 125. This is an 03 wrench rabbit bike with PC exhaust, Vforce, and pump/race gas mix. Fun bike but coming off of 450s and 250 two strokes, I couldn't believe how dead the low end is on these bikes lol. The race gas helped and I've since drilled 3 one-inch holes on each side of the airbox. That woke it up a bit too. Just trying to fine tune the jetting on the Mikuni now. Also will be going from a 52 to a 53 rear sprocket.

Try the 05-07 air boot b4 gearing.  It improves the low to mid then breaths better mid to top . Power flow cage was the next thing I tried more of the same improvement. I,m 172 lbs stock gearing is good . I might drop a tooth. 02-03 is a mid range bike.  Cases where stuffed to race the 125 gp,s. 04 case stuffing was not needed. 05-07 totally diff engine. I installed a 04 pc pipe on a 06. Off idle snap & quickness was crazy good but it stopped reving at 9k. 

Power flow air filter is smaller. Holes in the box helps more then. 

New coil, power flow cage, pc shorty, reeds boyeseen pro or carbon tech mid to high tension.  Carbon tech has 3 diff tensions. Low to mid gives up ovr rev. Mid to high still has good low end .  Holes in air box& jetting . Run the stock pipe with that. Quicker, snappier runs cleaner. If you need more power get a pipe.  Rad valve improves low & mid you can feel a torque difference. A little pricey tho. 

Actually I think the stock suspension pretty good, even at  my 190lbs. 

FMF Fatty Pipe/Shorty Silencer

V-Force Reed Cage

VP U4.4 32:1

Main Jet 390-400

Pilot 40

1.25 out air screw

(PWK is one of the best mods if you want to spend the money)

53T Rear.

This won't be popular....but thats Varner's stock set-up. 

1 step further is his mild port and polish and the bike screams. Proceed with caution on that one.

what elevation you at with that setup?

Oops FMF