Low End Carb Sputter

[BETAGAR]

I have a new 300rr race edition and I'm dealing with a 1/8 to 1/4 throttle sputter (blubber is another word). I put in a JD jet kit and was back and forth with them with settings, to no avail. Today I spoke with them again and they told me to take the carb from KTM 250 and install it on my 300, NO CHANGE. That means it's not a jetting issue. He thought it might be an ignition problem. Has anyone dealt with this issue and is there an easy resolution or shall I take the bike back (just kidding).

[ricoyam]

Was it blubbering before you did the jet kit?

[GMP]

Yes, did it sputter stock? My 300 has been fine jetted by the chart in NJ. Problem with JD needles is there is no option for fine adjustment. No half clip different needle and Blue, Red diameters are several sizes apart. They either work good or they don't. I'd look toward the NEDJ/NECJ to clean up a low end rich spot.

[BETAGAR]

Yes, out of the crate sputter. So I ordered the JD kit, used all needles and clip settings, mains and pilots and still no change. That's what prompted the carb change from my KTM 250 and the bike still had the same low end sputter. The guys at JD are pretty negligible with this and came to the conclusion it must be an ignition issue or something related to it.

[GMP]

Easy enough to troubleshoot, swap the KTM CDI in, same Kokusan hardware. Coil too. Before that though, I'd eyeball the reeds. Classic symptom of bad/broken reeds. Not likely either but what is on a new bike?

[Hyde]

Make sure your spark plug cap is all the way down.

[BETAGAR]

Talked with Beta today, they told me to unplug and clean all electrical connections, check the reeds and put the carb back to factory settings. So I did all that, didn't really notice anything unusual but got it back together and the bike started right up and had good throttle response. The real test will be tomorrow, I'll take it for a ride. I'll keep you guys posted.

[DaddyTJ]

Talked with Beta today, they told me to unplug and clean all electrical connections, check the reeds and put the carb back to factory settings. So I did all that, didn't really notice anything unusual but got it back together and the bike started right up and had good throttle response. The real test will be tomorrow, I'll take it for a ride. I'll keep you guys posted.

What all items did you unplug and clean? Just the CDI box?

[Hammer]

NECJ best money spent IMHO

[BETAGAR]

All wiring connections right down to the battery. I did not remove the side cover, I'll do that today if there is no improvement.