Xr650l jetting with fmfq4 slip on

I have a 2012 xr650l in stock trim. I have a fmfq4 slip on to put on it , just wondering what size pilot jet and main to use. I dont want to get into drilling slides and de- snorkleing id just like to change the getting and maby the air filter. Is there anyone running anything along these lines.


Probably leave it alone.

Probably leave it alone.



^ do that ^

There has to be someone running just a slip on with jetting, would fmf themselves point me in the right direction for jetting? I really want to git rid of that stock exhaust.



It's a system


If you change one, you have made the others worse

There is a reason the bike is delivered quiet/choked up/ lean jetted.


If you change the pipe, you will be making it leaner, so you HAVE to change the jetting.

Once you do, there will be a big flat spot in the power band, because you have not opened the air box.

Once you open it up, it will be even leaner, and need ever richer jetting....

The carb is a CV type, so you will start to notice the throttle lag even more, after that, and they you will want a new pumper carb....


Do not use FMF or Dyna jets, as they are not flow tested.


There are probably 150 articles on how to 'uncork' the XR/XL 650's.............do a google search.

What do u mean by flow tested?

I Am not up to speed on all this stuff. I contacted fmf directly and they told me to bump up the main and pilot jets one size and i may have to adjust needle or fuel screw for finer tuning. I am at sea level to maby 1500 or 2000 '

I googled fmfq4 slip on installation instructions and it says at sea level/70 deg use 52pilot and 158-160 main.

Any suggestions?

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