So I took my SF off road today for the first real time for some pretty technical trails and I have nobbies on not the street tires before any bashing starts. Well my question is how can I change my jetting/ tuning for good "all around use". I primarily ride my bike on the road and my jetting seemed to be spot on both while at idle and low throttle as well as the high throttle with the main jet and needle settings. But today however while on these tight technical trails I was on and off the gas alot and clutching rarely going anything more than 3rd gear and with all the on and off the gas there seemed to be alot of popping no real backfires but just popping when I would let off the get back on the gas hard there wasnt any bogging or lack of power but it just didnt sound right and when im riding on the road its pretty steady on steady off so I didnt really expirence this until today..

So how can I fix this or is it normal and I shouldnt worry about it. I use to ride alot of trails as a teenager on my RM125 and am just now getting back in my comfort zone with off road riding so I will be hitting the trails more and more and dont want to burn up my motor in the process. Should I up the pilot jet or mess with the a/f screw its at about 2-3/4 turns now and my clip is in the middle on the needle. and I have a 128 Main but it is fine at higher speeds and throttle it seemed to be when I was quick on and off the gas...

Sorry for the long post just trying to provide as much info as possible to get this fixed.

 

It doesn't sound like a problem. My experience has been when I'm trail riding that if I'm too rich in the pilot jet circuit, or if my fuel screw is turned out too many turns, I get hesitation and bogging when I crack the throttle. This when I haven't been opening the throttle much past quarter throttle, or when I'm on the pilot circuit. In other words when I'm riding technical trails. I pop my plug and it confirms it - black and sooty. I think I have the smallest pilot jet there is, a Keihin 35 (yes? no?) but I ride at high altitude so rich running is a fact of life. What I do is screw in the fuel screw to compensate. Since you don't have bogging and hesitation when you crack the throttle you probably aren't running rich like me. And your popping on deceleration sound like what a whole bunch of other people experience and I believe it to be caused by running a bit lean. Easy way to check: pull your spark plug after running around at 1/4 throttle or so. Does it look lean? My guess is it will. Edit: Maybe it will - I'm not certain about that.) But since your bike responds well at low throttle and still performs at WOT I wouldn't worry about it. From what I understand these engines are pretty sturdy and not prone to burning up. Maybe change the pilot jet to one size bigger and if you get bogging go back to the original size. Fine tune with the fuel screw. Hope this helps (or even makes sense!). Good luck!


PS - Maybe it sounds different because you're on dirt instead of pavement?

 

I wouldn't turn your screw out any further you run the risk of it coming loose and falling out when you're riding. Sounds normal to me my bike pops a little bit during off the throttle in 2nd gear, I have the #40 pilot jet in. I wouldn't do anything maybe check your spark plug see if you are running rich as Guido said. If you aren't then maybe up the pilot jet size. Do you have any other mods done which might affect it? Also changing your gearing may put you at higher RPMs in the trails and avoid what you're seeing. Its pretty simple to swap from a 14T to a 13T and vice versa, should only take you about 15 minutes max.