So I've got a K+N air filter on my bike, and it has a Micron exhaust (which makes the bike sound awesome). I've read on here constantly that doing exhaust and air filter requires rejetting.

I'm inclined to beleive it's not a bad idea for the following reasons:
-I am only getting 33mpg, and am only two teeth up in the rear.
-When I start the bike with the clutch out I have to twist the throttle a bunch to get the bike to start up.
-The bike has tolerable low end torque, and starts to get up and go around 7k, but after that I don't feel it's significantly larger in power, as the power curve should suggest.
-When engine braking from a higher rpm I get a popping sound out of the exhaust sometimes.


So... what's the story? How would you advise jetting a bike with modifications such as mine?

 

Bueller?

 

generic tuning would say up in jet sizes if you're doing jets since detonating on deceleration is a sign of being lean.

 

I would say I have to suggest the Dyno-jet kit. If you can get it, of course. If I recall, you don't live very close to me.

Their kit is what I have in my bike, and I have essentially identical modifications. I actually used to have a Micron pipe as well, but that came off in favor of this incredible yoshimura I found.

I tend to dislike the prepackaged fuel-mixture-in-a-box approach to jetting adjustment but with four carbs it is pleasant to let someone else do the thinking for you.


EDIT: I nearly forgot! I know people REALLY like the factory pro. Something about the needles being of higher quality or not oxidizing like the DynoJet ones or something to that effect.

 

Mine does the same on decel, was told by a friend to change the slow jet from #38 to #40. Have not tried it yet though.

 

If you are getting popping on decel you need to go bigger on the slow jet. usually 40 or 42. The bike is creating a high vacuum on the engine side of the carbs with the butterflys shut. It is trying to get more fuel but cant because of the jet size.
It is not detonating. Detonation is when you are in say 5th gear doing 20mph & try to give it a lot of throttle to get going. The knocking & pinging you hear is detonation & is very bad for the rings.
With the air filter & exhaust system it can flow more air but also needs more fuel to compensate for extra air being introduced in the system.
Did this happen all of a sudden? Like did you put the filter & pipe on & then it start doing it, or was this stuff on & after a while start to notice a problem?
Does it have a jet kit already installed & just need to be retuned for the addition of parts?

 

I purchased the bike and it had the exhaust on it, and I have no idea if it had been rejetted. I immediately went and purchased a K+N filter, as I knew the bike needed an entire work through given the poor condition I received it in.

I replaced the spark plugs, the oil, the chain, the sprocket, the air filter, oil filter, coolant... pretty much a stock "tune up" minus the valve adustment and carb clean as I don't have the garage space for such work. It also came with a fuel filter installed inline which I left in there, although I am uncertain as to the necessity on this bike. I know it's really popular to install on the Kawi EX-500. I redid the cam chain tensioner as it was blatantly toast. The front axle speedo assembly was toast, and required replacement, and lord knows how long it was bad for. The rear tire was toast as well, and the break fluid was chocolate like in color.

Anyways, this was all done in the first three days of having the bike. Because of this I don't have a baseline, which is a stupid move on one hand, then again on the other hand the bike was blatantly neglected due to a less than dilligent owner. I was able to find some history of the bike on the forum, and it appears the neglect largely came from the current owners incompotence. He wrote posts just weeks prior about his fear of getting on the highway, and apparently had only gotten on the highway twice. I'm betting he just bought the bike and did not a thing to it between the purchase and sell date.



So I have no basis for comparison in regards to the popping or the flattened top end. I will replace the needles though as you guys advise, and I am probably going to go with the Factory Pro jet kit as it is advised as having higher quality needles that don't oxidize.

Question:Is it worth paying the few extra $ for titanium needles?

 

Replace the slow jet with the next size up, no need to touch the needles unless they are leaking.
I look forward to hear how it goes..

 

Alright this all sounds decent. When the weather allows and I have the spare time I'll work on this project.

More questions for you all:

Changing the slow jets... perhaps I just don't understand enough about carbs, but will this only resolve the popping on decel, or will I notice a performance change elsewhere on the bike? I don't have a flat spot anywhere that I can notice really, however I do feel like the bike isn't getting as much as it should at high speeds.