Jump to content
Sign in to follow this  

RB Designs Head Mod Jetting in CA

Recommended Posts

I recently had my stock '05 YZ250 head done by RB Designs. He lowered the squish band to run on premium pump fuel. The mod was a great improvement in the way the engine ran. It sings now like a super clean running 125. The mod also reduced the spooge factor by about 90%. This alone was worth the price of the mod.

Since the mod, the spark plug is showing even richer than the "normal" wet YZ plug (??). I feel I need to lean the jetting out somewhere but the bike runs great and I cannot figure out where the motor is running rich. I will admit I am too lazy to spend half a day (a whole day for me) running the bike and pulling plugs on the trail, blah, blah.

If anyone has a similar set up, and has some jetting advice, I would surely appreciate it.

Senior A Rider

Single track to wide open fire trails at Hollister Hills and other parts of CA.

Stock cylinder, carb, pipe, with filter skins on stock and Uni air filter

FMF Turbine 2

91 Pump gas, Golden Spectro at 40:1, 1/2 ounce of octane boost per gallon

Share this post


Link to post
Share on other sites

Just my 2cents, if it runs better now with less spooge, I would let it ride.

Otherwise check the pilot circuit. That's the easy one to verify.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

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

Reply with:

Sign in to follow this  

×
×
  • Create New...