Jetting help please!
 

Hi All, I am the proud new owner of a 2013 XC300, but am having trouble getting it to run properly. It didn't run too well on my short test ride before purchase, but bike seemed solid. I took it for a longer ride and it ran strong on the pipe at wider throttle positions, but burbled down low, I also heard some detonation on a light throttle. I pulled the jets to check everything, original 42 pilot was partially blocked, I swapped in a new 40, main was ok. I put in a new BR8EG, new air filter, new 94 octane 50:1. I am at 3000', temp was 15c (60f) it now runs worse. I have a N1EF on 4, 40 pilot and a 168 main. Any suggestions on which way I should go would be gratefully accepted, thanks.

Review the jetting threads. N1EF is a very poor needle. Almost anything else will be much better.

N3CH, N3CJ, NEDW are all good needles. Pitch the N1EF in the garbage. Also really surprised you were hearing detonation out of this motor. That is just something they don't do. Sure you weren't hearing the power valve rattle? They are pretty notorious for that.


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As others have said, ditch that needle. I have a 13 300 also and am running a N3CJ (yz250) 2nd clip, 42 pilot and 178 main. This is perfection:D

Thanks guys, I am not very familiar with this motor, it could be power valve rattle, I have been a long time 4 stroke guy so not a noise I'm used to hearing. I have ordered a NEDW, as no one around here had a N3CJ. Hope that sorts it out. Thanks again for the replies.

Update_ Got a NEDW needle and that has really helped things out. I am now running the NEDW needle on the second clip, 168 main and 40 pilot, air screw at 2.5 turns out. I suspect that I am still a bit rich on the pilot as it starts from cold without the choke. Think I may try a 38 pilot to clean up the last little burble. I'm at 3500' and temp was about 12 C during testing. My riding area is higher and its finally getting warmer in the frozen North so a bit leaner should help. If anyone has any suggestions I'm happy to hear them, thanks,

Did you back off the idle and reset your air screw when you swapped to the new needle? if you didn't reset these after swapping needles it will be "off" - you will still be "pulling over"... Where is your idle screw at now - is it still nearly "coil bound" (all the way in)?


It might also help to know which slide your bike has...

jeff

Thanks Jeff, I have a 38 mm AS II carb with a 7 slide. I did adjust the idle screw, had to back it out 2 or so turns, my air screw was at 1 1/2, now 2 1/2.