WR jetting with mods: What is your's?
Posted May 10, 2003 - 02:14 PM
My '99 WR400 had a 172 main and a 48 pilot and fuel screw 1 1/2 turns out with just the throttle stop and airbox-lid mods. It always left the plug black and sooty but started reasonably well and made more power than I can handle (but when did that ever stop us from tinkering? Too much is never enough! ). I live in Iowa, so not much elevation and our temps this time of year vary greatly on a day to day basis from low 40's to high 80's. Soon, it will be just plain hot and muggy.
It now sports: custom YZ450 exhaust cam (Thanks cw !), grey wire unplugged, Big Gun exhaust (tapered headpipe and Race Core), a P-38, a YZ OBEJP needle (middle 4th position), and the JamesNow mod. I have not fired it up yet since doing these.
I am working on trying to do a version of Garret's fuel screw mod right now, too, before I put it all back together. I would like to jet to run easily obtained Amoco Ultimate 92 octane gas. I have read many posts where the jetting and plug condition changes with the type of gas, so I thought I had better mention that.
The book I have says stock main was a 168 and the stock pilot was the 45. These bikes were reputed to be rich from the factory, so I don't know why the previous owner went even richer . I figure the much better flowing BG exhaust will lean things a bit by itself, and the YZ needle should, too. I don't want to toast the motor by going too lean right off the bat, but I don't want anymore black sooty plugs either.
I was going to return to that stock jetting (168 main/ 45 pilot) unless one of you experts advises differently? I have a few other jet sizes on hand that I can play with: 172, 170, 168, 165, 162 mains and 40, 45, and 48 pilots.
I trust Yamahadude's advice to start from stock using a YZ needle. So now that I have found out what "stock" actually IS, that is my current plan. I am curious to see what some of you guys with similar mods are running, though...
Posted May 12, 2003 - 05:11 AM
Posted May 13, 2003 - 12:21 AM
Posted May 13, 2003 - 12:55 AM
Oh, and is that #2 position from the top or the bottom of the needle?