YZ 125, How to get more bottom end power?


44 replies to this topic
  • Azmatikz

Posted October 28, 2007 - 06:21 AM

#1

I finally got a chance take out my 03 yz125 today and felt a bit dissapointed, its got a load of top end power but it takes so long to reach the power band, and on the short tracks im racing on the power comes in to late for any good, any ways i can get the power to come alot sooner?

I have fmf full exhaust and Vforce reeds so i dont no what i can buy to help this out.

  • minibikedad

Posted October 28, 2007 - 06:25 AM

#2

I'd be sure that the jetting is right on. it could be too lean on the needle, and then it transitions onto the main circuit and everything starts pulling hard. Best way I've found to get more power off the bottom and mid is to go w/ a straight taper needle. $5 mod.

  • dtkiko

Posted October 28, 2007 - 06:35 AM

#3

I finally got a chance take out my 03 yz125 today and felt a bit dissapointed, its got a load of top end power but it takes so long to reach the power band, and on the short tracks im racing on the power comes in to late for any good, any ways i can get the power to come alot sooner?

I have fmf full exhaust and Vforce reeds so i dont no what i can buy to help this out.



[COLOR="Blue"]does your handle pertains to the performance of your YZ, as in azmatik (asthmatic)? :worthy:

proper or spot on jetting is the key to get that thing in best running condition :worthy: [/COLOR]

  • Azmatikz

Posted October 28, 2007 - 06:39 AM

#4

[COLOR="Blue"]does your handle pertains to the performance of your YZ, as in azmatik (asthmatic)? :worthy:

proper or spot on jetting is the key to get that thing in best running condition :worthy: [/COLOR]


Yer i was thinking the jetting aswell, because the person i bought the bike on put on a new carb without tuning it right with the exhaust.

  • mark dude99

Posted October 28, 2007 - 04:04 PM

#5

add a few teeth to the rear sprocket

  • SpDyKen

Posted October 28, 2007 - 04:23 PM

#6

1st, Jet.

2nd, Re-jet some more.

3rd, Repeat step 1 & 2 until it runs GREAT!

4th, Consider what other modifications you want to make your YZ perform better in the riding conditions you experience.

I promise you'll be happy, IF, you carefully study and follow the recommendations in your owner's manual, Section #7, as well as the jetting threads located at the top of this forum.

Good luck!:worthy: :worthy: :worthy: KW

  • KillerHiller

Posted October 28, 2007 - 05:12 PM

#7

add a few teeth to the rear sprocket


Ditto!

  • georgeforeman

Posted October 28, 2007 - 05:20 PM

#8

add a few teeth to the rear sprocket


:worthy:

  • SpDyKen

Posted October 28, 2007 - 06:28 PM

#9

add a few teeth to the rear sprocket

Yea, so you have a poor running, slower, YZ. :worthy: :eek:

Do you want to fix the problem, or not?

I am not saying that you should not change the gearing, in the future. But "adding a few teeth" will NOT cause your bike to run correctly, or make any change, at all, in the way it runs. It will simply allw you to ride your poor running bike around a bit, until you foul a spark plug.

My '03 YZ125 has GREAT low-end, now that I've re-jetted; My '06 YZ125 has unbelievable low-end. You can too, but not with a sprocket.

Learn to jet now. (It takes some time.) Many rewards; not much money!:worthy: :worthy:

  • CRF250dude26

Posted October 29, 2007 - 03:10 AM

#10

The clutch is your low end on a 125.

  • SpDyKen

Posted October 29, 2007 - 08:06 AM

#11

The clutch is your low end on a 125.

True, if you are not interested in jetting it properly.

My '06 YZ125 has as much low end as my late '70's & early '80's 250cc CR, KX, & YZ's had, now that I've rejetted it.

  • Azmatikz

Posted October 29, 2007 - 08:11 AM

#12

Thanks, im going check some stuff on jetting.

  • Denn10

Posted October 29, 2007 - 08:12 AM

#13

Yea, so you have a poor running, slower, YZ. :worthy: :eek:

Do you want to fix the problem, or not?

I am not saying that you should not change the gearing, in the future. But "adding a few teeth" will NOT cause your bike to run correctly, or make any change, at all, in the way it runs. It will simply allw you to ride your poor running bike around a bit, until you foul a spark plug.

My '03 YZ125 has GREAT low-end, now that I've re-jetted; My '06 YZ125 has unbelievable low-end. You can too, but not with a sprocket.

Learn to jet now. (It takes some time.) Many rewards; not much money!:worthy: :worthy:



DUDE chill out with your jet the bike 10 times stuff!!! I think they got the point when you said to jet originally. Get off the jetting drugs your on.

ONCE you have your jetting correct then if your not satisfied i would add 2 teeth to the rear and see how you like it

  • SpDyKen

Posted October 29, 2007 - 09:51 AM

#14

ONCE you have your jetting correct then if your not satisfied i would add 2 teeth to the rear and see how you like it

I think you said the same thing as me, when I said, "I am not saying that you should not change the gearing, in the future.":prof:

Azmatikz said that the carb. had been changed. I was pointing out that changing the gearing will not help his bike run correctly.

Many people believe that 125's cannot have low end. Those people need some "Jetting Drugs!":applause: :worthy:

BTW, Denn10, I fully intend on staying on the "Jetting Drugs" I'm on! :worthy: Cool phrase you came up with, IMHO.:worthy: (I only found 4 "Jet your bike" comments, not 10.):eek:

  • Yamaha4lyfe

Posted October 29, 2007 - 12:44 PM

#15

i think we have had enough people say your jetting needs to be spot on. first, buy a pipe for it. a FATTY, Get V force Reeds, then Send you Cylender off to Procircuit and have them port it!!!!!!!! or you can buy a dremil at Canadian Tire or Homedepot and Port it yourself. Port both Ports, Polish The Exaust port and leave the Intake with 320 after you open it up. add a tooth to your rear sprocket. run a twin air filter. it will make it alot better, if not? bore it to a 150 or a 175. then you will have better bottom!@ ooo and if you port it, you should have a noticeable amount of hp gain

  • Markopolo400

Posted October 29, 2007 - 01:04 PM

#16

or you can buy a dremil at Canadian Tire or Homedepot and Port it yourself. Port both Ports, Polish The Exaust port and leave the Intake with 320 after you open it up.


Yeah, ummm. No. He could do that if he wanted to ruin a cylinder.

You forget to take into account the port size, shape, spray angle, location...The list goes on.

  • Denn10

Posted October 29, 2007 - 01:28 PM

#17

Yeah i agree MARK that guy went a bit overboard LOL good stuff to do but not port yourself unless youve done a few succesfully, AND if i was gonna do all that work id just buy a 250 LOL

  • Pothole

Posted October 29, 2007 - 01:48 PM

#18

So, I'm really confused after reading all this. Can proper jetting help the low end on a YZ125? :worthy:

  • Denn10

Posted October 29, 2007 - 02:48 PM

#19

yes, improper jetting in the 3 major areas has to be on pretty well and it changes from summer to winter. You CAN and i HAVE noticed it cuz one time i was changing jetting and got to the track and said "hell ill go moto a bit then do it while im resting" went back and felt the snap out of the corners. From that day on about 10 years ago i have known how important jetting can be. You dont have to change it every month but using a summer and winter is more than most people do since they leave it be all year the same.

  • Pothole

Posted October 29, 2007 - 02:52 PM

#20

Thanks Denn..although I was trying to be sarcastic :worthy:





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