That's right, I have a GS450!  It's an 81 and it only has 3300 miles!  It has been in my family since new...but now it has an issue...it's too slow.  I pu pod filters on it but I dont know where to begin jetting.  I figured this site could help since the GS500 is just a little bigger version of my baby.  Also, does anyone know where I can get an exhaust that will fit my baby?
Thanks for the help!
Anthony

Usually, one size up for every mod you do will get you started. Unfortuneately, jetting requires alot of patience and testing as it is not an exact science. You will need a good selection of spark plugs to do plug readings.

The carburetors may be different than the ones on the 500's.

First, look at where in the powerband the mod will affect. Pods, without a pipe, I'm guessing, will affect the mid- to high-range of throttle, so going one up on the main jet size and shimming up the needle is what I suggest.

I.e.: current main jet size-120, go up to a 122.5. Common main jet sizes are available in increments of 2.5.

Also, if you can find your mixture or pilot screw, turn that out some. The mixture (or, pilot) screw handles the bottom end, but can make a world of difference. Every little bit helps. Start with 1 and a half turns out from all the way in.

Note: if you are already going to replace the exhaust it may be best (to save time and money) to jet for when it has the exhaust, which may be another main jet size up.

Quote from: avc8130That's right, I have a GS450!  It's an 81 and it only has 3300 miles!  It has been in my family since new...but now it has an issue...it's too slow.  I pu pod filters on it but I dont know where to begin jetting.  I figured this site could help since the GS500 is just a little bigger version of my baby.  Also, does anyone know where I can get an exhaust that will fit my baby?
Thanks for the help!
Anthony

Back in 1980 I put pods on a GS 450 with the stock exhaust.  Unfortuately, I do not remember the stock sizes - but I recall that I went up at least three sizes and added two #4 washers under the needle and went up one on the pilots - pretty much the same thing as with a GS500.  With a 500/pods and stock exhaust I would start with 135 mains - probably do the same with a 450 -

QuoteI put pod filters on it but I dont know where to begin jetting.

I'm sorry to hear about these individual filters.  Hope you didn't destroy the airbox by ripping it out of the frame.  Because, without a kit, you can't jet it satisfactory and kits are n/a.  She'll take 150's on the main jet, but shimming the needles won't cover the midrange hiccup that results.  And even WFO, there's no speed to be gained.  Been there and done that.  We just can't resist, can we?   We can't be satisfied with keeping the bike clean and polished, well maintained and well ridden.  Personalizing the bike with mirrors, or blinkers, or plug wires, or reflective striping won't satiate our inner Mr. Hyde.  We just have to muck it up with so-called  performance mods.  Oh, well.

MAC should still have the 2-into-1 for the 450 leftover in the inventory.  These are dang loud but will save weight, however, the stock 2-into-2 is thought to be ideal for extracting power from the 180 deg. crank configuration.  The stock GS450 does produce decent low-to-midrange power--something the GS500 is known to be lacking.

Quote from: Gisser

QuoteI put pod filters on it but I dont know where to begin jetting.

I'm sorry to hear about these individual filters.  Hope you didn't destroy the airbox by ripping it out of the frame.  Because, without a kit, you can't jet it satisfactory and kits are n/a.  She'll take 150's on the main jet, but shimming the needles won't cover the midrange hiccup that results.  And even WFO, there's no speed to be gained.  Been there and done that.  We just can't resist, can we?   We can't be satisfied with keeping the bike clean and polished, well maintained and well ridden.  Personalizing the bike with mirrors, or blinkers, or plug wires, or reflective striping won't satiate our inner Mr. Hyde.  We just have to muck it up with so-called  performance mods.  Oh, well.

MAC should still have the 2-into-1 for the 450 leftover in the inventory.  These are dang loud but will save weight, however, the stock 2-into-2 is thought to be ideal for extracting power from the 180 deg. crank configuration.  The stock GS450 does produce decent low-to-midrange power--something the GS500 is known to be lacking.

I think that you are wrong about no way to tune this without going to a performance exhaust - I have been there, done that with both a GS 450 and my current GS500.  Admittedly you get a benefit from going to the exhaust - but both these bikes are far more restricted on the intake than on the exhaust and good gains can be made from the pod and jetting.  Kit most definately not needed if you can keep your wits about you and read a plug.  I have done jetting both ways - and, yes, if you go with the kit you do not have to make a lot of decisions - that is if the kit was put together with exactly your combination of equipment - then its a mess until you do the same testing and changing you would have to do with the DIY methods.  The big place you gain with the kit is that you have a needle with a different taper - but, unless you are a racer you probably will not notice the difference between a well done DIY job and the kit.  The erly GS450 engine is very similar to a GS 500 and should end up within one jet size of a GS500 -- and the DIY method works great with the 500.

I have been thinking back to the 450 though - and on re-thinking it I am pretty sure I did not replace the pilot jets - just adjusted the mixture screws.  the 450 was one of the first emmission rules bikes and was lean - but not where near as lean (in memory) as the 500 on warm-up.

The 1980 GS450ST that I used to have was jetted excessiveley lean fron Suzuki.It took forever to warm up on warm days and acted like it never would warm up on cold days.I shimmed the neaddle valves.I puleed both throttle slide (diaphram type carbs), and put little shims under the neaddles.Aftre that the bike warmed up faster, and ran better, and the gas mileage stayed almost the same at about 64-66 mpg.

   Jon Neet