Taff, a question for you...


I was wondering how your spec'ed out timing sprockets would affect your jet specs relative to my jet specs?

Also David, I am unsure as to how my Stroker setup affects my jetting. I must assume it is freer flowing than your Euro exhaust, but nowhere near an E-series w/ 12 discs. Does freer flowing mean to go richer...???

I rode my bike for the first time w/ the following:

- 99 WR

- YZ timed

- MAJ passage drilled out to 2.8mm (7/64"

for us yanks)

- MAJ drilled out to 2.3mm (#43 bit)

- PAS @ .75 turns out

- EMN #2

- 172MJ

- 45 pilot

- 1.5 turns out on fuel screw

- de-octopussed

- stock airbox

- grey/gray wire cut

The first thing I noticed was when nailing the throttle, the bike would die. This is the first time I have experienced this. The bike was slow to come down in RPM after chopping the throttle. I played w/ the fuel screw until I reached 1.5 turns out. The bike is still slightly slow in coming down.

I believe the bike has better midrange. I could almost pull the front wheel off the ground, at speed, in 3rd...

I plan on doing extensive carb shooting today. I am off to a local OHRV park where I can work away from home, for a change.

Would the larger pilot jet require more turns out on the PAS?


'99 WZ/YR (you choose!) with ALL YZ mods, de-octopused, DSP Doug Henry airbox w/ velocity stack, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, OEM YZ tank, IMS YZ seat, Mobil 1 15W-50.

[This message has been edited by NH Kevin (edited October 22, 2001).]

well, it's always a guess but i expect the difference between stroker and euro to be about 10 on the MJ.

the MJ would normally seem about right but i think it may be lean given that you have the 235MAJ.

a 170MJ would probably do a std MAJ at #200MAJ. can't you buy a 160+200MAJ and try them?

have you ever thought of disconnecting the APJ just to see what would happen, or at least shorten it's stroke by putting a block connector on the silver rod.

you could abandon the rubber gaiter for a day while you tested. that way the APJ can only pump until the block connector hits the entrance. never tried it but it would shorten the stroke even though you can't make it start later in order to miss the slide.

you could try turing the PAS in to 5/8 (#75) to cure the cough but it's more likely that a RICH mixture is putting out the spark. you're running APJ and a 45PJ to my non APJ and 35PJ so are you lean?-no! you're flooding it!!!

so the answer is probably that you need the 42PJ and the PAS at 3/4 (#85).

and don't worry about all this crap about if you turn the PS right in it should stall the bike! that only applies when the bike has an inbalance of PAJ/PJ.

i see that you've gone a long way toward the jetting settings i offered but you sre running a higher PJ and a lower PAJ than offered and that's where you're having trouble so...


[This message has been edited by Taffy (edited October 22, 2001).]


I replied to this yesterday, but clicked on your "edit" vice reply. I lost the entire reply.

I went to test as planned. Things that went wrong:

Started out my testing w/ the Hot start valve unknowingly opened. The bike ran...DUH lean. After screwing w/ the fuel screw and idle to no avail, found the valve operned. I had to find my happy medium AGAIN, 1.5 turns out.

A local resident came running up to me to discuss my exhaust system. I was told that removing a stock exhaust to replace with a louder one is ILLEGAL. At my response of "Where did you hear that?", he told me the Fish and Game Department. I then told him a forester guy meticulously checked my bike over and found NOTHING ILLEGAL. He then wanted me to implicate the Fish and Game guys for NOT doing their job. Then the resident wanted to know where else I ride, where I live, how I found out about this riding area. I asked him what he did for a living (other than harrass motorcyclists). He told me he runs a crane for construction. I should have asked about all the homeless animals that use to live in the areas him and his buddies are destroying...

I lowered my clip to #4 just to check out system response. When I popped the clip...Murphy's Law. Yupper, shot right out and landed in the weeds. After spending 30 minutes cutting the grass with a pair of scissors, I found it 15 inches from where I was looking. Put the bike back together and test rode. The area is deep sand so any power changes could not be felt, although I noticed no glitches in carburation. My day ended there.

For our AP, I have quite successfully altered the pump stroke timing w/ slide valve position. By trimming mm by mm off the bottom of the rod (where it enter the AP diaphragm), I have altered the timing. I now will be tapping the AP cover to install a set screw to mimic the P38. Juist hope I can seal the hole against fuel leaks...


'99 WZ/YR (you choose!) with ALL YZ mods, de-octopused, DSP Doug Henry airbox w/ velocity stack, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, OEM YZ tank, IMS YZ seat, Mobil 1 15W-50.


Get some thin fiber washers from the hardware store of the right diameter (Lowe's had them locally). Stack 4-6 of them together on the bolt/plug and measure how far the bolt comes through. File the end smooth where the rod hits it. By removing washers 1 at a time you will have an adjustment range on the pump stroke. Set the duration of pump flow just like the newer bikes using the BK Mod. Don't forget the pump needs some operation to refill and prime, to get the air out.

Be very careful tapping the cover and tightening the plug bolt. It's not very thick and only about 3 threads will be holding it in. Mine worked perfectly and never leaked. This was before BK adjustment screw was public knowledge on the '00 WR.

Good luck.



where was your rabbits foot, still in the locker?


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now