TRX250R.ORG

Workshop => Engine and Bottom End => Topic started by: 2k1lvr on October 21, 2013, 07:45:56 AM

Title: jetting?
Post by: 2k1lvr on October 21, 2013, 07:45:56 AM

88 motor stock stroke stock port 67.20 bore, cr ignition,v force3 reed cage,38as carb, trx5 pipe cool head with 18cc dome vp110 gas live in indiana. What jetting do you think I need? Thanks

Title: jetting?
Post by: PORTED R on October 21, 2013, 12:05:39 PM

I would start at a 170 main and drop down
50 or 52 pilot
2 turns on air screw ,work in and out
Needle I would start on the 4th clip from bottom
That's pretty general for a starting point
For the cr ignition ,not sure on plug gap,I think around,.26,.25 or .24
See if anyone else chimes in

Title: jetting?
Post by: Jerry Hall on October 22, 2013, 11:10:36 AM

Quote from: 2k1lvr;15329

88 motor stock stroke stock port 67.20 bore, cr ignition,v force3 reed cage,38as carb, trx5 pipe cool head with 18cc dome vp110 gas live in indiana. What jetting do you think I need? Thanks

You omitted two of the most important things that will affect your jetting!!!



We need to know what your intake set up looks like ( the type and size of air filter and the shape/length of the connection between the carb and air filter)

We need to know if your TRX5 pipe is center mount or out of frame silencer.



The bore size, reeds and ignition has very little effect on the main jet size.

Reeds can affect the  pilot jet, needle and clip position.

The dome shape or volume has little effect on the main jet.

Different brands of race fuel can sometimes affect the main jet as much as 3 sizes to get the same power.  

The needle taper/desiginator and clip position will often affect the optimum main jet size.

I assume your altitude is about 1000 to 2000 feet elevation temperature average is around 80 deg. F and humidity is around 50 %.

Title: jetting?
Post by: Jerry Hall on October 22, 2013, 11:18:06 AM

Quote from: PORTED R;15338

I would start at a 170 main and drop down
50 or 52 pilot
2 turns on air screw ,work in and out
Needle I would start on the 4th clip from bottom
That's pretty general for a starting point
For the cr ignition ,not sure on plug gap,I think around,.26,.25 or .24
See if anyone else chimes in

You did not state the needle designator.  Different needles will affect which pilot, slide and main jet will be an optimum combination.

Title: jetting?
Post by: 2k1lvr on October 22, 2013, 04:01:28 PM

it has a uni foam filter dgh needle stock intake boot and stock airbox and boot with no lid and std mount trx5 with power core 2 muffler

Title: jetting?
Post by: rk88r on October 22, 2013, 05:54:57 PM

I would start with the needle in the middle or fourth clip from the top if it's cool out. If you experience a lean spot at 1/2-5/8 throttle ditch the dgh for a dej.