[locky86]

Hi

Just installed a FMF Ti Powercore 4 with a Titanium powerbomb header pipe on my CRF450X. Have got alot of conflicting information regarding the jetting. I have been told it will be fine with standard jetting, but the header pipe glows red hot when it is warming up on the choke, seems to be alright when I ride it though. Has anyone put this system on before?? Do I need to rejet the carby?

[crfsonly]

for most locations the stock jetting is lean. we've had excellent results with the JD Jetting kit we offer. you can also check the jetting database to see what others are using at similar altitudes/weather.

ken

[locky86]

yeah I've heard about the JD jetting kits. Riding in WA around Perth. Not usually far above sea level. From past research the consensus seemed to be to go up a size on the main jet. will have a look at the other thread. cheers

[crazybrother]

If your jetting is stock, you will need to re-jet:
165 main
JD Red needle/4th clip or
NCVS needle (Honda OEM part# 16233MEN671)/4th clip
50 leak jet
R&D flex-jet fuel screw

That should get you started, then work from there to get it dialed in.

Setting the fuel screw mixture-
Try adjusting with the motor fully hot, and turning the fuel screw inwards until the idle slows or runs rough, then turn outwards 1 1/4 turns from this position. For example, if the idle slows or runs rough at 1/2 turn, then set the fuel screw to 1 3/4 turns out (1/2 + 1 1/4 = 1 3/4).
See- http://www.pbase.com/jdjetting1/image/82894252 to understand how the fuel screw can affect the idle speed and air/fuel mixture at idle. The target range for the air/fuel mixture is near 12.5 to 13:1 at idle.

[gal8x]

I also highly recommend the R&D fuel screw. I found it does not back out like the OEM screw was doing at 2 ¼ turns out.
http://www.crfsonly.com/catalog/product ... ts_id/2792

[Tiger094]

If your head pipe is glowing red, you have a real lean pilot jet. Go to a 45 pilot and an adjustable fuel screw to fix your lean condition at idle and 1/8th throttle. When you install the adjustable fuel screw, screw it in all the way and gently seat it, then back it off about 1 full turn. Start the bike and let it warm up completely. Step1: Then slowly back the fuel screw out and listen for a slight rise in rpm. When the rpm stops rising, stop and take note of where the screw location is. Step 2:Now slowly turn the screw back in until the the engine starts stumbling and stop. Turn it back out 1/2 of the amount of the turns it took from step 1 to step 2, that will put you where you need to be. If you are more than 2 1/2 turns out from fully seated with the fuel screw then you need to go up to the next size larger pilot jet. Im going with a JD kit also. Look at adding the quickshot 3 from Boyesen to dial in the leak jet.