V force jetting??? YZ 250

Rcannon

Subscriber
Joined
Nov 17, 2001
Messages
1,886
Likes
0
#1
I recently added one of these to my 1997 YZ 250. The bike allready had an FMF Gnarly torque pipe and shorty silencer. It is otherwise stock.

The bike was jetted pretty well with the stock reeds. Due to the altitude I am at, one step leaner was all the bike needed with the stock reeds and cage.

With the v force added, the plug went black...very black. I have leaned th emain down several more sizes (from the stock 168 to a 160), but that formerly coffee and cream colored plug is still very black. I also went with a needle that is one step leaner than stock.

I like the way the bike responds with the v force in it. Do these things cause the bikes to run much richer???

Am I wasting my time trying to get the plug back to the origional color? I would appreciate any and all help with this...thanks!
 

jmics19067

Lifetime Sponsor
Joined
Jan 22, 2002
Messages
2,097
Likes
0
#2
yeah things will recquire leaner settings with the vforce . I cant give you much of a direction to go but I can state that I followed Eric Gorrs book for a homemade port job, Vforce block and c12 fuel on a 94 yz 250 and ended up with a pilot jet that was 5 steps leaner and a needle that was 2 sizes leaner.

If you happened to have read Bclapham's thread on his jetting woes I also had similar issues with that 1/4 throttle area that I chose to live with that bike's mikuni.

Not much for you to go on but your findings of being too rich all of a sudden is not uncommon.
 

Studboy

Thinks he can ride
Joined
Dec 2, 2001
Messages
1,818
Likes
0
#3
The V-Forces do typically make the bikes run rich.
I am running a lot leaner on my bike than stock (I am in Utah also.)

Is it worth trying to lean out? YES!!! I don't think that you have too far to go though, because when I rode your bike it ran good.
 

bclapham

Lifetime Sponsor
Joined
Nov 5, 2001
Messages
4,340
Likes
0
#4
smaller pilot!:)

btw. still jetting woes, got a brand new PWK carb and cant get the bike to run properly no matter what jets or needles i try- i am having to run the mikuni carb still if i want to ride at the tracks.
 

Rcannon

Subscriber
Joined
Nov 17, 2001
Messages
1,886
Likes
0
#5
Thanks! I will continue after it. The leaner needle helped, but I may need the next leaner as well.

I tried a leaner pilot and was not very happy with it.
 

fuzzy

Subscriber
Joined
Jul 26, 2002
Messages
447
Likes
0
#6
btw. still jetting woes, got a brand new PWK carb and cant get the bike to run properly no matter what jets or needles i try- i am having to run the mikuni carb still if i want to ride at the tracks
Move for the better on the carb (IMHO). Might want to try a different slide. rbdesigns.com will cut it for you to get it leaner, and he's a very good resource for PWK questions in general(mainly does KDX work, and these have PWK's stock). I'm also in the process of getting a PWK working correctly on my WR250, but things seem to be going good for me(used OEM KDX 35mm PWK/slide).