Jump to content
Sign in to follow this  

125 Power Issue

Recommended Posts

Hey everyone.

 

I was able to take my '92 kx125 down to briarcliff to ride. I'm having some issues with power. It seems like my 1st, 2nd, and 3rd(could be better but not THAT much of an issue) work just fine as far as revving through the RPM range. Once i get into 4th gear, even if i hit the limiter in 3rd, it just takes a long time to rev into the powerband area. 3rd gear is kindof like this but its not that bad, its manageable if i just grow a pair in corners and hang it out. Below are some specs on my bike. 

 

Jetting:

Floats - 16mm(stock)

Pilot - 45(stock is 48)

Main - 158(stock)

Needle - middle position(stock)

 

Aftermarket parts:

Boyesen Rad Valves

FMF Fatty header

Pro circuit 304 silencer

 

Rider weight - 295lbs

Ignition timing is advanced for a harder powerband hit. 

Usually i have to clutch the bike to hell to get any power out of corners which i am assuming is completely expected for a rider of my weight and such a small engine size. But i dont think i should have to ride the clutch in 4th gear to get up to speed. My brother who weighs 140lbs is having the same issue in high gear as i am. It just takes a long time to rev out. Once it does get there it hits nice and hard. My dad has been telling me that 92's were kindof slow bikes to begin with, so maybe thats it too. Would a gearing change fix this? The exhaust has a lot of black soot where the header and silencer meet. Not sure if thats normal for a 2 stroke. I've been reading a lot about jetting and i dont really know the audible difference between a bog and sputter when people describe rich and lean situations. Any help would be appreciated! 

Share this post


Link to post
Share on other sites

300 pounder riding a 125 ?>????

 

First off....^^ dont' do that. You clutch will be fried in a week. They are made for 165lb riders on a track.

 

Second; until you rebuild the top end and the crank seals, there is no way to know what kind of power you actually can have from this old motor.

 

Third: Yes, you will absolutely have to slip the clutch to reach top speed at your weight, especially if the dirt is loose or sandy.

Share this post


Link to post
Share on other sites

Haha yeah im working on shedding weight. The 125 is just what i've had. Im getting a 250f soon. But back on topic, the engine was completely rebuilt with all new seals and things of that nature. the top end hasnt been done for a little bit. Maybe 30 hours ago and since then i was mostly putting around the yard and trails. 

Edited by Acidreamer

Share this post


Link to post
Share on other sites

Haha yeah im working on shedding weight. The 125 is just what i've had. Im getting a 250f soon. But back on topic, the engine was completely rebuilt with all new seals and things of that nature. the top end hasnt been done for a little bit. Maybe 30 hours ago and since then i was mostly putting around the yard and trails. 

 

30 hours is a long long long time on a 125c  track motor.

 

You know that the two strokes have to have the piston and rings replaced TWICE as often as a fourstroke motor, right ?

 

Racers build their 125cc motors between motos.....just to keep the power up .

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...