After considerable test rides, and jet swapping, my opinion is don't do it. It's certainly not worth the $100 and many hours I spent finding out. Previously I've upgraded the exhaust and occasionally A/C, with accompanying jetting changes on two street bikes and two quads. The power increase has ranged from noticeable to dramatic. I've also added free flowing exhausts to 3 trucks with added HP there too. Just adding the K&N offers no appreciable increase in horsepower on the GS. I believe it's because there's no where for added air to go with that ultra quiet exhaust. I refuse(so far) to upgrade the pipe since I plan on getting a new (larger) bike next year. As of now I've got 40 pilot jets in, 2 #4 washers, stock (122.5) mains and the K&N. I've put the restrictor back in since there's no gain without it. The bike actually runs better with the 122.5 mains. :dunno: I think they like running lean. These are very finicky engines as is evidenced by all the posts asking for tuning tips. My advice is either increase intake and exhaust flows to match(punch holes in the pipe if you have to) or just get it jetted right for the stock A/C and pipe and let it be. Unless I crash this puppy I'll have a nice used GS for sale next year with progressive springs that's half way to hot rodded, just add the exhaust.

Disclaimer: Actual results may vary. Your experience may be different. Subject to local climate. Not valid where prohibited by law.

hey ed... what about drilling the baffle of the stock exhaust... i saw a thread a few months ago about this... six 3/8 holes around the outlet... would that open it up enough to use a K&N with some gains?
I have been thinging about that, along with a re-jet.... but if it's not a noticeable gain, I wont bother

Quote from: cummuterguyhey ed... what about drilling the baffle of the stock exhaust... i saw a thread a few months ago about this... six 3/8 holes around the outlet... would that open it up enough to use a K&N with some gains?
I have been thinging about that, along with a re-jet.... but if it's not a noticeable gain, I wont bother

:dunno: If you've got the money for the filter / jets, it might be worth a try. I'd bet someone here has tried it. They might reply.

hopefully....

Thanks for this post Ed_in_AZ!

I had asked this very question since I was thinking about either Pods or K&N replacement with stock exhaust.  I know some people have said it can be done but I wanted to know if it was worth the $$$.  I want to get something for the money.  For example the progressive springs were worth every penny.  I ended up just putting in one #4 washer for each needle and I noticed a little improvement in throttle response.

Thanks again!

You did not say which version of the K&N you installed.  My guess is that you went with the one in the airbox.  You then attribute the lack of power increase to the restrictive exhaust - I think that what the real restriction is is the air box.

On my 2001 I did not try the K&N in the box.  My own re-jetting story started with the stock filter in the box and no other changes.  Going up one on the pilot and adding a washer under the needle clip combined with opening up the mixture screws to 3 turns resulted in much better throttle response and quicker warm-up.  One up on the main gave my seat of the pants dyno a little tickle - but mainly seemed to fix a dead spot in the power curve on full throttle and popping back while cold -

When I went to pod filters I found that I needed to increase the main jet substantially - its been a while and I am not sure of the size, but I believe I was at either 137.5 or 140 with everything running quite well and measureably better performance on my uphill test route.  This was a much bigger increase than was needed when I added an exhaust and an ignition advancer - Like most people here I ended up at 150 mains.  If I was jetting for the track I might be one or two sizes smaller on the main - but on the street rideability is more important than the last tenth hp  -- and two strokes taught me never to jet lean unless I wanted my wallet to be lean.

You could well be right about the airbox. I did use the drop in filter. :dunno:

the way i did mine was..., 3 (3/8") holes in outer baffle, and 2  (1/2") holes in inner 2.5 turns out on screws, 140 mains, and stock 37.5 pilots. hella quick, plus sounded evil going down the road. got to hear it when the person that ended up buying it, rode it.after i did that it was quite fun to ride, also had put in 15t front sprocket

OK Ed one reason you might be better with 122.5's is... in AZ in summer its extremely dry and blazing hot. That means even slightly rich... you'll pay the penalty. I did most of my jetting, and continue to jet mainly in winter. I want driveability, and a guarantee its never lean (like mjm says). The 125's might be right in winter for you... I'd run 125's now, and no washer under needle right now, and in winter put a washer. easire than jet change. Or add a pair of washers in winter with your 122.5's.
Cool.
Srinath.

I think I'm becoming a fan of electronic fuel injection for bikes. A new SV650 would be nice.

The GS did run quite well to work today other than the idle was off since I put the restrictor in. Even with gloves on it wasn't too hard to reach down and adjust it while riding. That's a plus.