Need input from guys w highly mod 250r's

[250rmanfmf]

Hey guys,

A few a you may remember me. I am the guy with the Yellow 85 250r. I havent been around the site in a while because of other things happening but now I am back. my 250r has changed a little and now I am trying to get it in good perfect shape but need some help.

Heres what I need input on. I need to know what main jet and piliot jets *Edited* guys are running with Highly modified 250r's. I need a starting point to work with. Here are my mods

250r;
Cylinder Port and Polish for racing
Shaved Head
Modified Stock reed cage with Boyseen Reeds
40.5mm Kelhin Flat Slide Carb
K & N custom open intake
38mm-42mm Intake Boot
MSD Adjustable timing Ignition
Full FMF Fatty pipe and silencer
BR9es plug
.60 Over Wiesco Piston
Im running a 13/39 gearing
110 octane

I was running a 37mm carb but upgraded to a 40.5. It came with a 185 main and a 58 piliot.

I just am interested in what you guys are running

Thanks for any info

Tyler

[ChrisD]

That's probably pretty close. In my 270R I run a 195-200 main in the winter. In the summer, it's a 185-190 (depending on how cold or warm it is). I do run a 60 pilot jet. (39 PWK)

I run a 175 main in my 330R in the winter and a 60 pilot (40.5 PWK). The bigger motor has lower velocity than the 270, thus the smaller main jet.

[TeamGeek6]

250r;
MSD Adjustable timing Ignition
BR9es plug
Tyler



Kudos, someone finally did it right. There is no hopping a 250R that much on a stock ignition and expecting it to do anything but overheat. That 9 heat range should go, itll cause misfire. Run a 6 gapped at 0.050" then monkey with the timing a little, should find more grunt.:beer

Im using a "5" with extended tip and a 132 main jet down from 145 on a stock PJ bored out and modified out the ying yang.

If that isnt enough spark for your arc, I can build a GM HEI system for it. High compression takes more spark power, y'no.

[250rmanfmf]

On the MSD Ignition it says that you need a BR9 To run the best with the ignition. Thus the only reason why I did a 9.

Thanks
Tyler

[TeamGeek6]

take a spare head, screw that 9 in and look at where the gap is considering the angle the plug enters the head, at most degree angles its shooting right into the side of the head. Its shielded way too much. The spark gap must be exposed to the air/fuel charge and thats tough to do when its recessed up inside the head. I use a 5 with extended nose and even it barely sticks inside the chamber. Never had any overheating problems with a 5 although ya gotta watch for carbon buildup on the threads.

[ChrisD]

mmmmmm....I don't know about any of that...but I think you're fine. I would take it out for a ride, do a "hot lap" on it, then shut it down (don't idle). Pull the plug and see if it's a brown color. If it isn't white and dry, you're all set.

Good Luck!