Shimming the Needle

[sam000lee]

I recently changed my exhaust/intake, and am beginning the carb jetting process. I have two sets - one from and '80 and one from a '81 gs450. I want to lift the needle slightly, and opened both pairs up to see if either had the adjustable needle - neither do. So I was going to replace the orange plastic bit that sits on TOP of the needle clip with a something a little thinner (so the needle would be higher). I noticed that on the '81 carbs (but not the '80 carbs) there is also a thin metal washer underneath the needle washer (I am calling the clip/washer that is on the needle itself the needle washer).

Question 1: Does it make a difference if I add space underneath the needle washer or take away space above it? I want to use my '80 carbs, so was thinking I could just take the little washers from the '81 carbs and put it underneath the needle washers in the '80 carbs.

Question 2: Once the needle is in, there is that pointy orange plastic piece that sits on top and then the C-clip that holds it all in. In the carb body, there are two places where it looks like the C-clip can sit. I think the original configuration was for the clip to sit in the lower groove and I was wandering if this was designed to be another way to adjust the carbs (i.e raise the needle by putting the C-clip in the higher position.

Heres the '81 carb needle showing the extra washer underneath the clip:

Thanks in advance.

 

[JTGS850GL]

Question 1: Does it make a difference if I add space underneath the needle washer or take away space above it? I want to use my '80 carbs, so was thinking I could just take the little washers from the '81 carbs and put it underneath the needle washers in the '80 carbs.

You need to shorten the stack ABOVE the e-clip on the jet needle. You can go to a Radio Shack and pickup a washer assortment. You only need one size washer but the pack contains enough to do the entire set. You'll want to stack 3 washers in place of the stock plastic washer.

Question 2: Once the needle is in, there is that pointy orange plastic piece that sits on top and then the C-clip that holds it all in. In the carb body, there are two places where it looks like the C-clip can sit. I think the original configuration was for the clip to sit in the lower groove and I was wandering if this was designed to be another way to adjust the carbs (i.e raise the needle by putting the C-clip in the higher position.

There should be only one groove that the top circle clip sits into. That would be the lower grove. The assembly should be able to rock back and fourth a little when assembled.

 

[sam000lee]

Awesome - just what I needed. I think it was $2.50 for the pack of washers. Here's some pictures:

 

[Guest]

No need to add any washers under the clip, that only adds preload to the spring, it does not affect the height at all.

 

[sam000lee]

In both of the "what I believe to be" stock carbs I have for the 450, there is one washer under the clip and then the orange plastic piece on top (which is what I adjusted to the 3 washer spec).