I have an 05 S40 with about 3500 on it.  I have only taken out the white spacer completely and put in a drop in K&N Filter.  I have the idle/fuel mixture screw out about two turns.

I want to know if I had the carb re-jetted, would it increase my top speed.  Right now I can get the S40 up to a max of 90-95 indicated on the speedo on a flat road with no wind.

I would like to be able to get it to close to that with a little wind and possibly a slight grade increase.  I do not have the money to put on a muffler or even a slip on on the bike right now.  I just want to see if a re-jet would be worth it for increased acceleration and top speed, mostly the top speed, as acceleration is very good right now.

Any ideas on what size to re-jet to.  I do not know what the carb has on it stock but would love to know what to go up to so I do not have to ask the dealer.  I would rather have advice from people who have done it.

Thanks

Howdy Jeff:

I can tell you that the stock main jet for an '05 is listed as a 145.  Jets for these carb commonly come in increments of 2.5.  Changing the main will richen up the top end.  Without more diagnostics it is hard to tell if a larger jet will give you more top end.  I'd start by getting a plug reading after a highway ride of some distance.  IIWY, I'd probably start with an increase to a 150 and reassess from there.

I think Reelthing is right though.  If you can't get it out, you can't use more.  Your exhaust/OEM muffler is holding you back.  I might suggest that you check with some of the independent H/D shops in your area, looking for a take-off muffler from a Sportster.  I got my for $25.00.  The stock Sportster muffler is pretty much a straight swap.  It will be better then the stock muffler, performance wise, a little lighter, a sound a little stronger.  It won't be as loud, or perform as well as a Jardine, Rask, or other performance pipes, but it's a darn site cheaper.

There is alot of jetting info on this site.  Have you tried to do a search yet?  It will be worth your time.

Hope that's helpful.

Adios, David

The biggest performance improvement with this motorcycle comes with an exaust upgrade. I installed the SuperTrapp years ago on my 2002. It was an instant and very noticeable improvement in acceleration in all the gears. The worst job is rejetting, which you have already done. By the way, the SuperTrapp weighs 10 pounds less than the stock muffler.
Normally, people install the performance muffler, notice the great difference in acceleration, wait till the pipe turns yellow, then they rejet the carb. After that you have to polish out the yellow before it goes blue.
So, part with the the $300, and get the SuperTrapp and be happy you can now blow of most Harley Davidsons up to 60mph. Sell some of your wifes jewlry so you can get the SuperTrapp and stop screwing around!  

I've been a widower for 15 years and clearly remember the limitations of marriage, that's why I never remarried. Now I own a sports car and a motorcycle and can easily afford the SuperTrapp.   I sold my wifes jewlry years ago, but I invested that money.   However, I do sympathize with your current situation.  :'( You might consider holding up a gas station for the money, surely they are rolling in the dough now.