05 cr125 frankenmotor

So after 9 four stokes and countless valve jobs and overpriced parts I've thrown in the towel,

Picked up a 2005 cr125 and have been doin alot of research to build a reliable yet powerful motor, I've been away from 2smokers for a long time and need some advice, here's some of my options

1, double stacking base gaskets

2, double stacking reeds

3, running a 96 cr125 jug with a 98 powevalve..

Possibly depending what year bolts up running a whole mid 90s motor for the 6 speed tranny and power gains.(not sure on fitting of the pipe now having a aluminum frame and the motor mounts.

I'm looking for a all around power but pump gas and still a 2 ring piston for rideable woods and motocross power, anyone with knowladge of interchanging jugs and powevalves and piston I would love to here usable combinations and also opinions on staying stock and just porting...

So many choices don't know what to do but winter is almost here in Michigan and that motor is coming out

Oh an for kicks I swapped the forks out for some off a crf450 I had sitting around, worked great bolted right into the 125s trees had to swap front brakes as well but huge improvement!

As far as I know Honda hasn't had a 2 ring piston for the 125 since the 80's.  You can do a tranny swap and put a 6 speed in the 05 case, there is a writeup on how to do it somewhere, I would bet a google search would find it.  No need to swap cylinders, if you want great power have it ported for the power you want, if you are just using it for a play bike have Eric Gorr do a 144cc big bore kit. 

when i had a 93' CR125 i put two base gaskets and a double set of boyesen reeds. read about it in one of the old motocross magazines and figured i'd try it. now that i know what i know about squish i probably would have not done 2 base gaskets. but buying 2 sets of reeds and installing both made the bike sound like a 250 and turned it into an animal. i crashed the first day i got on it after that rebuild, and i never crash on 125's.


i dont know if the 05' cr125 uses a dual stage reed like the 250, but the best thing to do would be to install 1 set of carbon fiber and get the other set the standard fiberglass, put the carbon fiber reeds on top of the glass ones.


stiffer reeds helps the top end by getting rid of some of the flutter inherent in reed valves and 125 are all top end anyway so it works great for them. by putting a carbon fiber reed at the top will add some spring like tension. so 1 set of boyesen superstock fiberglass reeds and 1 set of the superstock carbon fiber.

Will adding a extra set of reeds affect the low end?

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