Procircuit jetting - Motorcycle-Journal Forums

MikeFry · 02-25-2006, 03:42 PM

hi i want to get a Procircuit works pipe and shotry silencer for my 1997 rm 125. does anyone have any idea what kind of re-jetting i would have to do? does the pipe come with a new jet?

ALLEYCAT50 · 02-27-2006, 09:26 AM

Here is a place to start. Make sure that you read the paragraph above the specs. Use this as a guide only. Jetting on a 2-stroke is never set and leave. Usually you only have to turn the air screw, unless the season changes. If you are not using race fuel like they are or if your altitude is different you will have to make changes. Good luck!
http://www.fmfracing.com/jetting_center.aspx

MikeFry · 02-27-2006, 01:53 PM

thanks for that! the 32:1 will not really matter right? because i run 40:1 i've read here that 40:1 is o.k. with stock. will there be some kind of indicator, with the new exhaust, that i need to make adjustments?

ALLEYCAT50 · 02-27-2006, 02:07 PM

40:1 is fine, as long as you mix 40:1 all of the time, if you change ratios you will probably have to rejet.

As for the pipe, depends on where the pipe is designed to make power, you should see a difference, but if you ride in the low to mid range most of the time don't buy a pipe that designed to make top end power, you could actually lose low end power.
There is a section here on pipes and how they are designed to change performance.
Hope this helps.
http://www.lukesracing.com/luksr/tips.html

Also your indicator will be the how the bike runs and the plug color.
Search here for Spanky's jetting guide.

MikeFry · 02-27-2006, 08:58 PM

thanks for the advice. i pulled out my spark plug and it was black, it was not wet with oil, according to my manual it was carbon fouled but it is not fouled, i haven't had any probs,whatso ever scence i bought the bike in november, but i haven't done much riding. hopefully it will warm up soon in CT so i can re-jet my bike. i'm suspecting that my bike is just a little rich because the plug is not fouled, but it is still black.

ALLEYCAT50 · 02-28-2006, 09:34 AM

Sounds like you have a pretty good idea of what you are doing. good idea to wait for the warmer weather.
Good luck.

Dave2122 · 03-01-2006, 08:26 PM

Ideal conditions for jetting a bike are 50% Humidity at 70 Degrees.

digipoi · 03-01-2006, 08:55 PM

Bought an FMF Gnarly pipe and could not use their specs. Jetting is bike specific, too darn hard to have a universal configuration.

ALLEYCAT50 · 03-02-2006, 06:08 AM

Good point. I made sure that I mentioned earlier to use it as a starting point only.

02-25-2006, 03:42 PM	#1 (permalink)
MikeFry Where Am I ? Joined: Feb 2006 Posts: 34	Procircuit jetting hi i want to get a Procircuit works pipe and shotry silencer for my 1997 rm 125. does anyone have any idea what kind of re-jetting i would have to do? does the pipe come with a new jet?

02-27-2006, 01:53 PM	#3 (permalink)
MikeFry Where Am I ? Joined: Feb 2006 Posts: 34	thanks for that! the 32:1 will not really matter right? because i run 40:1 i've read here that 40:1 is o.k. with stock. will there be some kind of indicator, with the new exhaust, that i need to make adjustments? Last edited by MikeFry; 02-27-2006 at 01:59 PM.

02-27-2006, 02:07 PM	#4 (permalink)
ALLEYCAT50 Seat Tester Joined: Jun 2005 Bike: 2008 YZ450 Location: NOVA SCOTIA Posts: 70	40:1 is fine, as long as you mix 40:1 all of the time, if you change ratios you will probably have to rejet. As for the pipe, depends on where the pipe is designed to make power, you should see a difference, but if you ride in the low to mid range most of the time don't buy a pipe that designed to make top end power, you could actually lose low end power. There is a section here on pipes and how they are designed to change performance. Hope this helps. http://www.lukesracing.com/luksr/tips.html Also your indicator will be the how the bike runs and the plug color. Search here for Spanky's jetting guide. Last edited by ALLEYCAT50; 02-27-2006 at 02:10 PM.

03-01-2006, 08:55 PM	#8 (permalink)
digipoi Seat Tester Joined: Sep 2004 Location: Honolulu Posts: 84	Bought an FMF Gnarly pipe and could not use their specs. Jetting is bike specific, too darn hard to have a universal configuration. __________________ 2004 RM250 2004 DRZ125L 2006 TTR-90E 2004 JR50 1993 RM250 1990 KDX200

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02-27-2006, 09:26 AM	#2 (permalink)
ALLEYCAT50 Seat Tester Joined: Jun 2005 Bike: 2008 YZ450 Location: NOVA SCOTIA Posts: 70	Here is a place to start. Make sure that you read the paragraph above the specs. Use this as a guide only. Jetting on a 2-stroke is never set and leave. Usually you only have to turn the air screw, unless the season changes. If you are not using race fuel like they are or if your altitude is different you will have to make changes. Good luck! http://www.fmfracing.com/jetting_center.aspx

02-27-2006, 08:58 PM	#5 (permalink)
MikeFry Where Am I ? Joined: Feb 2006 Posts: 34	thanks for the advice. i pulled out my spark plug and it was black, it was not wet with oil, according to my manual it was carbon fouled but it is not fouled, i haven't had any probs,whatso ever scence i bought the bike in november, but i haven't done much riding. hopefully it will warm up soon in CT so i can re-jet my bike. i'm suspecting that my bike is just a little rich because the plug is not fouled, but it is still black.

02-28-2006, 09:34 AM	#6 (permalink)
ALLEYCAT50 Seat Tester Joined: Jun 2005 Bike: 2008 YZ450 Location: NOVA SCOTIA Posts: 70	Sounds like you have a pretty good idea of what you are doing. good idea to wait for the warmer weather. Good luck.

03-01-2006, 08:26 PM	#7 (permalink)
Dave2122 Sprocket Pilot Joined: Sep 2004 Bike: Which one of the 9? Location: USA Posts: 887	Ideal conditions for jetting a bike are 50% Humidity at 70 Degrees.

03-02-2006, 06:08 AM	#9 (permalink)
ALLEYCAT50 Seat Tester Joined: Jun 2005 Bike: 2008 YZ450 Location: NOVA SCOTIA Posts: 70	Good point. I made sure that I mentioned earlier to use it as a starting point only.

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