New xr650 owner, check out my jetting situation

Just got a 2001 650. It was backfiring on deceleratiion. Former owner said it was jetted. Learned from rejetting a crf230 that things are not always as they seem.

I took the XR650 carb apart and heres what I got: A 172 main, a 68 (not S) pilot, needle clip on the second position(1 from top). The spark plug was a NGK BKR5E. The bike has a FMF titanium exhaust with powerbomb and the air box mod. I'm riding at sea level always.

What are your recommendations?? I'm thinking 175 main, 68s or 70s pilot(??) Middle position on the clip and BKR7E plug..

Open for any and all suggetions


is this an "L" or "R"? my thoughts if its an L like mine, remove the smog with the baja desings block off kit, is it the cv carb? that is a good start to fixing the"L" model poping. for an "R" go one more step fatter, needle position is prob. ok.

It's an R. Should have mentioned that first

Ambient temp info would help us help you, but the typical 'uncorked' setup is a 175 main at the third clip position.

Try here for more info:

Make sure the needle is the B53E needle. That is the needle that is used in the 3rd/middle position. A larger main jet than a 175 just might be in order with the FMF full exhaust and holes in the side cover. The 'S' pilot jets are obtained by ordering from the Honda XR650R carb parts menu. The part numbers don't list an 'S' in them but they are in fact 's' versions.

That site Porterdog gave the link to, does have a good jetting guide to get you in the ballpark.

Thats a good chart. I'm in NC, average year round temp about 65 and FLAT where I ride. I checked the needle and there is no marks on the needle. I guess thats stock and I need a B53E replacement? I'm reading some people are using a 70s pilot and less turns out on the mixture screw. I hate to throw this in the mix, but the bikes got Wiseco stickers on it. So maybe it got a different piston as well. I'll tell you one thing, even without tweaking, the bike rips! I want to eliminate the backfire on decel and I know it can be easier to start. The plug was not as "cocoa" brown as it could be

a general rule of thumb is that popping on deceleration is a lean condition. i would definately think you needle position is the most off circuit from what you gave us. i would try to third groove and maybe even the fourth. is this bike uncorked it is it completely stock.

See first post

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