Beta Riders Club Discussion Forum

New member and first dirt bike. Been reading a lot of the carburetor threads and have a question. When I turn the air adjustment screw all the way in till it seats, my engine still runs. From what I've read, this means the pilot jet is too big. Is that right?

This is after the engine has been warmed up.

you have that backwards.

thanks. The packet of extra jets from the Beta Dealership had a 35pilot, 168 main, and N2ZJ needle. Not sure what it has in there now.

Its a little weird that, according to the manual, the 250RR has a #38 pilot jet and the 300RR has a #35 pilot.

It should have the 35 in it stock but one never knows.

My 17' came with 38p, n2zw in 2nd pos. And 165 main in it.

I'm new to riding, so I'm betting its just two stroke noobs. But the air screw not making the engine die needs corrected, and I'm having a weird "ping" or "knock" whenever I'm running hot and let the bike coast after acceleration. But she sounds normal when giving her throttle.

From Beta USA:

The jetting for your bike is a 38 pilot, 165 main and a N2ZW needle. Depending on the temperature this is a good combo unless you’re riding in hi temps then I would swap the pilot to the 35 and lower the needle 1 position. The N2ZJ and 168 main might work well if you install a FMF Factory Fatty pipe as this is a richer combo. Please let me know if you have any other questions.

Most threads are concentrated on attaining as close to stochiometric cumbustion as possible. Does this take away from some of the 300RR best traits: best lug down low and ability to not boil over while doing it?

Without knowing where you are located and what altitude, it's hard to recommend jetting or air screw settings(not that you asked for it)

This is what I suggest: Set the bike air screw according to the Beta owner's manual. It will list settings based on altitude. Assume jets are the default stock jets, but check them if you want to be sure. If the bike runs well, don't touch a thing. This is your first dirt bike. Try not to get hung up on jetting, a clicker here and there, or if you're 1-2psi off on tire pressure. You have way more important things to worry about before those become something that holds you back.

I'm running bone stock jetting on my 300 and I run it from sea level to about 7k feet without changing the jetting. Does it run a little rich when I go to high altitude? Of course. But not enough for me to want to tinker with it. It still hauls ass and runs well.