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Q: I got a 2001 GS500 and I would like to rejet it.

A: There are two options. First one is buying a jetkit that takes all the guess work (well most of it) out of the equation. The two jetkits available are the Factory Pro Kit and the DynoJet Kit. The difference is that one comes with slides (DJ). If you do go the jetkit method use the instructions that came with your kit. The kit retails for about $80. Make sure when your purchasing the jetkit that its made for the 2001 and above models. According to MP183 the part number for the 2001-2002 is DJ-3150

The other option is to do a DIY jetting.

To rejet a 2001 GS 500 you need the following:

2* #20 bleed airjets / pilot (sudco part # 004.564 )
2* #62.5 mid-main (sudco part # 004-270)
2* #137.5 main. (sudco part # 004.300)
[ NOTE: #132.5 main has the part # 004.298 ]

Sudco sells these jets for about $30 + S&H.

3 Jets on a 2001+ GS500. Tallest is Main Jet, middle height is Mid-jet, Bottom is Pilot Jet/Airjet


You will also need a K&N airfilter to increase the available air intake.

You will need to drill out your Airmixture screws. Its on the underside of your carbs (will require you to take off the carbs) to access the brass plugs that cover the screw holes. Using an EZout one can drill the plugs a bit and pull it out.

EZ Out with Airmixture screw plug pulled out

It is highly suggested that you also replace the 4 mounting bolts of each float bolt with allen screws rather than the philips heads that are on there. To take the philips heads off you will need an Impact Wrench (best to keep carb on a hard stable surface when doing this).

The size for the Allen Bolts are: M4x10 by 1/2" long METRIC

This will allow faster changing of jets on the bike.


Also See:

What airfilter is required for my GS500.
How to Rejet - Step by Step Guide.

Quote from: Frostfor 01+ I found 2 errors in the FAQ

first...the allen screws are M4X0.7X12mm
NOT M4X10X1/2"long

second...the Main jet part number is wrong
I bought the main jets according to the FAQ but it looks NOTHING like the stock ones...wont even fit...

These recommendations come from member mjm from the GSTwin board.
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They come stock with 17.5 bleed type pilots, a number 60 mid-jet and 127.5 main jets. The formunla seems to be -

STOCK - increase main jet one or two sizes, shim needle with a washer, pilot screws out to 3 turns (to start) - most of the cold bloodedness goes away. If it doesen't, then go up one on pilot.

K&N pods - Go up a few more sizes, and one more washer on the needle - I ended up at 142.5 before I did the exhaust.

KN& Pods, Slip-on and Ignition advancer - up a few more sizes on the main - either 147.t or 150.

Another person on the board indicated that they were increasing the mid-jet to 67.5 - I [mjm] have no idea how that works out.

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That other person is Piper5177 who says the following in regards to a Stage 3 jetting:

I have been messing with this for a little while, and I have just about got it. Changed the needles to the ones from the 89-00 Dyno Jet kit, DNO348. They are smaller than the stock ones since they are for a 33mm carb and not a 34mm. But since they are smaller, the pilot did not need to be changed. I set them on the fourth clip from the top. I changed the main to a 147.5, and it has great top end.

The only problem is with the smaller 60 main jet. Those jets take care of the mid range up to around 6500 RPM. With the higher volume of air moving through the carbs they lean out until the carbs hit the 147.5 jets. I ordered some 67.5 jets and those should clear up the little flat spot. I tried shimming up the needles some more, but since the jets are lean the needle doesn't help at all. I have Vance & Hines exhaust and the UNI pod filters [and they flow surprisingly well].

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Flash from gstwin.com also writes: I did notice on your "Why re-jet a stock US bike" page you listed Part Number - 09420-40014 for #40 pilot jets. Could this possibly be a misprint? Maybe an old part number? I'm assuming you were referring to Suzuki Genuine Parts. The reason I asked is because I went to my local suzuki dealer with this number (you have 09420-40014 listed) and he said it did not exist. He told me the first 5 digits did not match up under the Suzuki Genuine Parts Catalog, but the last 5 digits did: part no. 09492-40014 What was funny is he told me the description just said "pilot jet". Since he knew I wanted size #40 he told me there was part no. 09492-40018 which had the description "pilot jet 40". I'm not sure if these were possibly bleeders because the pilot jets I ended up ordering (part no. 09492-40014), which were the ones which matched yours the closest, ended up being what I wanted: 1 Mikuni #40 non-bleeder pilot jet.

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I suspect the number difference is due to ordering it either through the dealer or through bikebandit.com or ronayers.com which would explain the differing first sequence of numbers but matching second set. fwiw, pablo-

Piper5157 also PM'd me this info...
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2001 GS500K1-K3 stage 3 jetting

Okay I am finished, and not changing it anymore. I have tested many many times and this is the set-up that I get the smoothest and strongest pull with.

Pilot #20 bleed type
Small Main #67.5 round slotted
Large Main #147.5 round slotted
Uni pod filters
Vance & Hines Super Sport Exhaust
V&H timing advancer

I use the Dyno Jet needles from the 89-00 kit, but shimming the stock needle with #4 washers will work too. I'm guessing 2-3 washers will do it on the stock needles. The Dyno Jet needles are set at the third clip from the top with one #4 washer underneath. I went to the #20 pilot jet and found a little more power at the bottom end. Fuel screws are set at 3.5 turns out. I don't think I can get it any better than it is right now. A 150 main runs a little bit rich for my taste.

Piper5177

The '04s are not the same as '01-'03.  The stock mains are 130s.  My rejetting:
http://www.gstwins.com/forum/viewtopic.php?t=19472

I'm going to be opening up a 2005 this weekend, with luck.