[SVmoto]

Heres the bike. 2002 sv650s, akrapovic full exhaust, kn filter, *re-jetted*
It has a nasty pop when im cruising between 4-6 grand then give it throttle. I dunno what to do about this, Ive tried everything, the thing that got me stumped is that it only does this once the engine is warmed up. It doesn't nearly over heat so dont say thats it.
any help would be greatly appreciated as the shop that jetted it isn't helping me :x

 

[Topher]

Its really hard to say without actually hearing or seeing it, but ALOT of people complain about a big flat spot between 4 and 6000 rpms. Its possible that to satisfy the aftermarket exhausts need for more fuel elsewhere that there is simply too much fuel being dumped at that speed.

With that said, I am about to order the 4 degree ignition advancer from maelstrom racing, which is said to greatly reduce the flat spot!

Blue is after the key, reds before!

 

[orangegilly]

Isn't it the shimmed needles that is supposed to cure that flat spot? Do you know if the shop that did the jetting also shimmed the needles?

 

[DrummerDaveB]

I agree with Orange.

You probably need another shim under the needles to richen it up through the midrange.
Give that a shot and see if it fixes it.

 

[bmetz99]

If it gets worse as the bike warms up, that indicates the mixture is rich and you may need to lower the needle, not raise it. This is also consistent with Topher's conjecture & dyno chart.

Bill

 

[DrummerDaveB]

If it gets worse as the bike warms up, that indicates the mixture is rich and you may need to lower the needle, not raise it. This is also consistent with Topher's conjecture & dyno chart.

Bill

Bill are you sure? Because, you have the choke on when it's cold, right? So this would richen the mixture. By my thinking, the bike would run richer in the midrange with the choke on, and the flat spot wouldnt be there. Then once warm with the choke off, the bike will be running leaner causing the flat spot.

Or am I confused?

 

[wonderjosh]

buy a 2003 model and pcIII .. then you can just push buttons to fix the problamo .. aah technology

:roll: j/k of course

 

[Kris87]

If it gets worse as the bike warms up, that indicates the mixture is rich and you may need to lower the needle, not raise it. This is also consistent with Topher's conjecture & dyno chart.

Bill

This is correct.

 

[orangegilly]

So when you "shim" the needles (per catpoopman), is that raising or lowering the needle?

I did mine about a month or so ago, and this was the first time I ever worked on carbs. Not too difficult, but I was just following directions.

 

[cos]

RE

orangegilly,

Shimming, as you did, is raising the needles which richens the mixture and cures the factory's EPA mandated lean jetting which causes a stock bike's "lean surging".

 

[SVmoto]

shims/ingnition

I found my jetting work order.
145 mains.
2nd Richest groove on needles
2.5 Turns
KN Air Filter and Akrapovic Full Exhaust
I will take everyone elses advice and move to 152.5 Mains.

 

[knee-dragger777]

Your pilots have a lot to do with this. Did you change them to 17.5? Why are you using the "2nd richest goove on the needle? Jet kit says to use the middle grove?

Did you ever make changes? What is the outcome?