What a difference .030" makes!!

[hikermikem]

I raised the jet needles in my son's '82 GS650G up .030" and that flat spot between 3-5K disappeared!!

I should also note that I re-adjusted the mixture screws because it was running quite lean too (each screw is now out approx 2.5 - 2.75 turns)

Now you can cruise in 5th at 2700-3000 rpm, turn the throttle and actually accelerate nicely!! \\/

My plan is to do some plug chops & adjust from there.

I'm still smilin' though !!!! :-D

[Nessism]

Did the same thing on my 850 recently and it made a very noticable difference; choke can be turned off shortly after starting now and the flat spot at partial throttle is completely gone. Highly recommended modification for all GS bikes with BS/CV carbs.

[hikermikem]

sooo..... if .030" makes a big difference, will .050 be better?? What's your experience?? The bike(s) are completely stock through & through.

[tkent02]

Is it still too lean at half throttle?
Hard to tell from here.

[hikermikem]

doesn't seem it, however i still need to do plug chops to confirm

[mortation]

Hmmm maybe I will try this later. What did you use to raise the needle?

[doctorgonzo]

I always feel like the outsider, heh. I'm always fighting too rich not too lean.

[Nessism]

Hmmm maybe I will try this later. What did you use to raise the needle?

Pull out the needle and remove the plastic spacer on top of the clip.

Get a couple of small washers with a total thickness combined about 1/2 as thick as the plastic spacer.

Reassemble the needle back into the slide with washers on top of clip. Net result is you will have raised the needle about 1/2 the height of the spacer.

If you have a hard time finding washers, Radio Shack sells a bag that people report work pretty well. Failing finding the washers, stack a bunch of small washers with the right ID (but too large OD) on a screw with a nut on the end and chuck up the whole assembly is a drill motor or dremmel. Use a file to dress down the OD until it matches that of the plastic spacer you removed.

Hope this helps.

[Suzuki_Don]

Pull out the needle and remove the plastic spacer on top of the clip.

Get a couple of small washers with a total thickness combined about 1/2 as thick as the plastic spacer.

Reassemble the needle back into the slide with washers on top of clip. Net result is you will have raised the needle about 1/2 the height of the spacer.

If you have a hard time finding washers, Radio Shack sells a bag that people report work pretty well. Failing finding the washers, stack a bunch of small washers with the right ID (but too large OD) on a screw with a nut on the end and chuck up the whole assembly is a drill motor or dremmel. Use a file to dress down the OD until it matches that of the plastic spacer you removed.

Hope this helps.

So are you saying that there are no needle clip grooves like in the VM needles. And you shim in between the clip and the plastic spacer to raise the needle.

[chef1366]

So are you saying that there are no needle clip grooves like in the VM needles. And you shim in between the clip and the plastic spacer to raise the needle.

In the great US of A we don't get those fancy notched jet needles. EPA control freaks. :?
That's why Dynojet is making a killing!

[strawboss]

Anybody ever try the 5/20 shim kits that you can get for sleds out of catalogs like Hiperf.com? This kit has shims at 0.010 increments for fine tunings between the 0.040 steps of needle adjustment. You would have to buy two twin carb kits at $8.95 each which I guess isn't too bad. Just an idea. I was going to buy one for my sled last year to mess with but I didn't get around to it. I am interested if anybody has played with these and the results that they got!!

[Nessism]

So are you saying that there are no needle clip grooves like in the VM needles. And you shim in between the clip and the plastic spacer to raise the needle.

On CV carbs the needle height is controlled by the thickness of the spacer above the needle clip because a spring under the needle pushes it upward.

[hikermikem]

Pull out the needle and remove the plastic spacer on top of the clip.

Get a couple of small washers with a total thickness combined about 1/2 as thick as the plastic spacer.

Reassemble the needle back into the slide with washers on top of clip. Net result is you will have raised the needle about 1/2 the height of the spacer.
Hope this helps.

Just for reference. The plastic spacer measures .100". The flat washers came from RadioShack in a bag that contained 20 each of several different size washers. The next to the smallest size in the bag is the perfect size. The thickness of each washer is .023".

I used 3 washers (total thickness = .069") in lieu of the .100" spacer, for a total needle rise of .031" higher than what stock spacer gives you.

I'm going to use 2 washers (as Nessism suggests) for a total needle rise of .054" on the CV carbs I'm currently rebuilding for my new "82 GS850GL project bike.

[chef1366]

You pretty much raised the needle 1/2 notch. :-D On the Dynojet needles two of those washers = one notch.
I measured
I know :-D

[hikermikem]

You pretty much raised the needle 1/2 notch. :-D On the Dynojet needles two of those washers = one notch.
I measured
I know :-D

How much is a notch? I thought is was .040" ? I raised it .75 of a notch, another washer then would equate to 1.3 notch I guess. i love numbers!!