Jetting 00 WR400 with YZ timing?
Posted May 26, 2000 - 06:47 AM
Posted May 26, 2000 - 10:59 AM
**** Side note - The stock clip position DRQ#4 looks VERY rich (like DVP#6) and could be a source of plug fouling at 1/4 throttle. You may want to experiment with a leaner clip position.***
My needle taper evaluation is in progress for the '00WR and there will be more power at 3/4 throttle when the best one is found....
[This message has been edited by James Dean (edited 05-26-2000).]
[This message has been edited by James Dean (edited 05-28-2000).]
Posted May 26, 2000 - 09:01 PM
Don't turn the fuel screw out more than 2 turns as you risk decreasing spring pressure on it amd loosing it, if you need to go more then you should be increasing the pilot jet.
RodH Canberra, Australia<A HREF="http://www.400thumpers.oz-au.com" TARGET=_blank>
400 Thumpers Australia</A>
2000 WR400F See Photo's and Modifications
Posted May 27, 2000 - 07:58 AM
Thanks for adding your comments. The exhaust is an unknown factor.
I've been trying to get the most performance out of my US '00WR with stock exhaust, no baffle, airbox lid off, shortened throttle stop. Extensive testing is in progress.(500' elev and 60F)
-Pilot jets run have been 42, 45, 48, and 50. (45 looks best, 48 is rich past 1 turn)
-Main jets run have been 168, 172, 175, and no main jet at all! (rode 20 miles with no main jet, it accelerates good but doesn't rev and never fouled out) The 168 ran about the same with or without the airbox lid and snorkel, 172 and 175 ran best with no airbox lid.(the 180 was speculation from feedback on the forum)
-Needles, 6 needles are being tested with 3 tapers and 4 straight diameters. The increased taper needles give more power at 1/2 to 3/4 throttle(no airbox lid). The YZ426 uses more taper on the needle. The YZ/WR400 needles don't have enough taper, they are too fat at 1/2 to full throttle and run lean, less responsive in this range. Thus the main jet becomes less important. There is more power left untapped here. If someone was used to an open class 2-stroke they would be disappointed!(read me).
-Any feedback will help everyone. I know there is not one perfect combination for every configuration (exhaust, intake, altitude, temp, rider...), but there will be an improved setup that will fit most. With some basic guidelines, we could post it as a starting point. Clark has the '99 dialed for everything (except taper) and that is an important reference.
- I'm Power Hungry...
- Any more feedback? Anybody? (add your setup to the jetting section on the forum)
- pilot, needle, clip, main
Posted May 28, 2000 - 04:17 PM
Posted May 28, 2000 - 07:16 PM
Sounds like you are trying to get me into a EVP needle?? After I get through with my pipe testing and bumping up to a 420 I will give it a try but not for a while too many projects at the moment and major stess at work for a month or so.
Posted May 31, 2000 - 09:03 PM
Yes you should try the EVP carb needle. (P/N 5BE-14916-EP) The profile matches the YZ426 jetting and it uses your best choice for straight diameter. Start 2 clips richer because the taper starts 4mm lower. This will have a cross-over effect.(lean/rich) The gain is at 1/2 to 3/4 throttle. Hopefully the clutch will handle the extra torque. (The 426 got a beefier clutch...)
At low altitudes and cool temps an FMP will have more boost yet. I expect that a multi-taper needle mixing DVP#4 and FMP#3 will cover a broad range with more torque. I will make one from a brass needle from Sudco and you can try it along with the EVP.
More will follow via e-mail