Alright, picked up an F3 about a month ago, and just took it into a shop for a full look-over before I take it on a trip later this month.

I have a Vance and Hines ss2r slip-on and a K&N filter, and the shop told me it's running lean. This explains the hesitation around 2,500 rpm, irregular idle, popping on deceleration (as far as I've read around this killer forum).

So my question is: If I rejet with a FactoryPro Stage One kit, will that be enough? I've heard that a slip on and K&N don't require rejetting, but it's definitely running lean.

Will I need to sync the carbs after changing the jets? Would a carb sync remedy the idle problem without rejetting?


Oh, also, the carbs are clean, so there's not an issue of anything being plugged.

 

All my research leads to say exhaust requires jetting, and a k&n filter is useless

 

Alright- that's mostly what I've been finding, too.

Wouldn't hurt to do an idle drop and see if that fixes the idle problem. I'll probably switch back to the stock filter and see if it improves.

 

I have a (presumably) stock filter, as well as a yoshi pipe and the bike runs horribly (bought it two weeks ago, said it had a fresh set of factory jets put in a month or two before that). I'm waiting on a jet kit in the mail this week and going to put a new stock filter in when i do the rebuild. It lags at lower rpms then suddenly takes off, but still feels kinda dry, idle is ridiculously bouncy. All my car tuning theory puts me at running too lean, which with the same symptoms I'd presume yours are as well. Get a factory pro kit, I just ordered mine from the one guy on ebay selling them for 110.

 

Because the K&N and slip on increase aspiration the fuel-air mixture is relatively dry but a stage one jet kit is the natural next step. I know it's hard, but read and follow the instructions. ((

 

A stage one won't be enough. With the exhaust and K&N you'll probably need 142's or more. Factory pro stage one comes with 138's 130's and 128's.
I just went through this on my F2. The solution for me was to pull the K&N and install an emgo paper filter. Amazon has them for around 25 bucks. I also had to order keihin 132 jets from motorcycle superstore because the factory pro kit didn't have the right size. Not a big deal. 12 bucks I think. I'm on clip 2 and 2 turns out and I'm almost perfect. I'm thinking I may try clip 3 to see what that does to my mid range and if it's to rich maybe try a washer to go to clip 2 1/2.
The f2 and f3 always had kind of a crappy mid range. A lot of 600's do. Most guys recommend keeping the rpms at 5k and above but I like to ride at 4 so I'm still messing with it. The biggest improvement I made though was pulling out that K&N the PO had installed.

 

The low rpm stumble is exactly my problem- As soon as it jumps past 3k, it takes off (quite well).

Stock jets for the F3 are 135 on the outside carbs and 138s on the inside. I believe a stage 1 kit usually takes it to a 140 and 142, respectively.

I've been hearing a lot of bad news about K&N vs paper filters, looks like I wasted my money.

The majority of the problem is in the low midrange. At higher rpms on deceleration, the popping isn't too bad. Then again, I usually ride with earplugs in so what do I know.

Any opinions on Dynojet vs factory pro?

 

Alright, ordered on of the Emgo air filters, and earlier today I got the motionpro D shaped tool so I can hopefully fix the bouncing idle (it was there before I put in the K&N).

I just want her to run smooth, it's such a beautiful bike for it's age. Well, compared to my beat-to-death '82 nighthawk.

 

If its below 4k then your mixture screws are off.
0-4k is pilot jet and you adjust with your mixture screws. 4-7k is your needles. You shim the needles to adjust this range. 7k plus is your main jets. You change main jets to adjust this range. Remember you have to start at the top and work your way down so first you need to select the correct main jet. Once you pull consistently through the upper rpm's you adjust your needle clip position. Again when it pulls fairly well through the mid (personally I think its impossible to get this area exactly perfect but perhaps someone better than me can) then you adjust you mixture screws to correct low rpm or you can up your pilot jet but this normally isn't a problem.
Remember this a a street bike not a nighthawk. If your in 5th at 3k and yank the throttle you won't take off like a rocket. It'll stumble and complain telling you to downshift. If your in 2nd at 3k you should go like hell.

 

Yes-you need 140-142's. I'm at 1400 feet altitude and runs great on the 3rd clip.