Ya'll,

  My 2001 is stock - for now - I plan to keep it close to that. I noticed that the top end speed feels lean. Runs great but you can tell it's not fully there. What can I do to the main jet and needles to richen it up a bit? I have a stock air filter and exhaust. Can I ever so slightly drill out the main jets?  Go next size up? Lift the needles a notch - if there is a notch on mine. (I haven't pulled them apart yet to see.) What about the mixture screws? 3 turns out? Any suggestions would be greatly appreciated.

Denny
Western Kentucky

If you really just want top end (at WOT), then you just need to go up one size on the mains.  Make sure you find genuine Mikuni jets.  Changing the mains will have some impact on the rest of the ranges too, but mainly from 3/4 to WOT.  You might want to do a plug chop to verify top end leanness before you modify anything.  If you have never cracked your carbs before, there is plenty that can go wrong if you aren't careful.

Quote from: Denny Lee on November 18, 2014, 05:22:07 AM
Ya'll,

  My 2001 is stock...................................Any suggestions would be greatly appreciated.

Denny
Western Kentucky

OK, my standard answer- "Don't mess with your carbs and they won't mess with you."

Seriously though, first make sure you carb bowl vent hose is located where high speed winds are not affecting it. 

The carbs on both my GSs remained untouched for the 180k miles I've put on them and I've been happy with them that way.  Never saw a need on the 02 which is same as your 01 using it year around here in NE Ohio for 11 years and 100k miles.  The 97 with the old 2 circuit carbs really needed jetting for winter use but I had an old CM400A I used for a winter bike to keep the new GS out of the salt water and it screamed right along spring, summer, and fall.

My 02 hasn't been near top speed and don't think it's been redlined either.  I did open up my 97 GS to 110 mph indicated years ago with a big plexi 2 shield and 240# me on board and it pulled smooth and strong all the way.

Have you looked at the jetting info in the wiki?  They use to go a size larger on the 2 circuit carb mains to make them the same as the rest of the world was using with good results leaving the rest stock with stock air filter and exhaust.

http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting

Keep in mind stock GS HP is at 8500 rpm and peak torque around 7000 rpm, I got the most out of that 97 running for hours on end at 7-9k rpm in the mountains.  Guess I grew up (got old) somewhere between the 97 and the 02.   

^^^ great answer

That +1 formula works on all GS'es.
They have different type jets and different numbers due to their different design, but 40/125 for 89-00 and 20/132.5 for 01+
Jetted to basically non EPA.
If you put 1 size bigger - say 22.5/135, you're bike will literally choke on its own gas.
You jet it to run cool, it may really not even make any more power (except in the coldest and wettest days of the year) and in hot and dry, it will be down a bit on power.
Anyway 01 stock, 20/132.5 kit.
$25 for a pack of the right jets.
Set air screw to 3 and the floats - check and make sure they're right.
Cool.
Buddha.

Just what I needed folks. Staying stock and living within these boundaries. Like I said my bike runs great - so I'll not try to fix what ain't broke.