2002 kx125 modded or get a 250?

binthedirtnow · Mar 29, 2005

Hi guys, I really need your advice. I have a 2002 kx 125. Now it already has an FMF fatty, boyesen dual stage reeds, and a new top end, otherwise stock. I am a novice rider, but learning pretty fast. So far I like to ride intermediate trails, fire/logging roads, and beginner and vintage mx tracks. I weigh about 165 without gear. But I will eventually want to ride normal mx tracks when I learn to jump better. I like the 125 - it's light, stops well, quick reacting, easy to maintain, and seems fairly powerful. These are all the traits I want in an off-road motorcycle. But I am starting to want more low-mid power so I can really roost!! So, I've been thinking, should I mod the 125 to get more roost power or do should I get a bigger bike?? Please give me your honest opinions... I would also like your opinions or experiences with the following mods I am considering for the 125 to give it more roost boost:
DSP powernow; Boyesen RAD valve; Gearing change(currently 12/49); smaller carb(currently TMX38); Flywheel weight(how many ounces?); Cylinder porting and head mods from Eric Gorr.
I am thinking I might want to mod the 125 because if I bought a bigger bike it would be used, and I don't know if I want to go through the thing fixing all the busted/worn-out stuff like I had to do with the 125 already. But if that is the best direction, to go with a bigger bike, then I will. Nevertheless, if the 125 could keep me smiling and roosting, I'd rather keep it! However, I'm not sure I want to do any big-bore/stroker mods.
B.

marcusgunby · Mar 29, 2005

A 144 kit would give more power and cost less.

bedell99 · Mar 29, 2005

I would leave the bike alone except for getting a port job by Eric Gorr and either a vforce or rad valve.

Erik

binthedirtnow · Mar 30, 2005

But how often would I need to replace the topend with a 144cc kit in this motor? Are there any reliability problems with such a modification to this motor?
B.

Canadian_Racer#120 · Apr 1, 2005

You're in the same boat as me, my plan is to buy a pipe and a port job from Eric Gorr. With more power always comes loss of reliability but nothing major. I think porting is included with a bore kit from Eric so I'd go with that if I were you.

bclapham · Apr 1, 2005

marcus is right, a 144 kit will make more power (and fun) than all of those mods put together.

as for reliability, i would put a new ring on every 5-7 hours and a new piston every 15-20 hours. you can get the rings cheap, and all i would do is pull the top end, new ring, base gasket and bolt it up. The best part is Erics piston and spare rings are the same price or maybe a bit cheaper than stock!!!

bikepilot · Apr 2, 2005

Frankly, IMHO you are not going to get enough low end power out of a 125 or 144 to be very useable. For example it doesn't really matter if it makes 1/8th or 1/4 of the power you need at low rpm to crest a particular hill or clear a specific jump. A flywheel weight will make the power come on more smoothly and will lessen wheelspin but will not increase bottom end power. I would recommed that you just work on getting more accostomed to the 125 untill you get good at keeping it in rpm band where it makes good power. do not be afraid to slip the clutch a bit if necessary to get the rpm's where they need to be comming out of a corner. for tight woods work it may help to gear down a bit (i.e. a larger rear sprocket). Starting out with a 125 typicaly makes you a good rider, switching to a 250 will make you lazy IMHO.

good luck and enjoy:)

thek · Apr 2, 2005

When you are even thinking of asking the questions you have just asked binthedirtnow, there is only one answer;

2 5 0

binthedirtnow · Apr 2, 2005

OK guys thanks for the input. In the future I'll have money for a 250, but for now I'm gonna stick with the 125 and add a few hopups like a good reed valve and maybe a port job. I already ordereda 51t for the rear srocket(stock is 12-49t). This should run it in a better power band better.
B.

2002 kx125 modded or get a 250?

Similar Topics

Privacy & Transparency

Privacy & Transparency