uni filter jet size?

[ipmaham]

1977 650D

Recently replaced old beat up filters with the angeled Uni filter. Also, picked up a Carb rebuild kit from Mikes that came with a #135 small main jet. Problem is, the description says it is for a 1980's and above.

Stock is 122.5, according to carb guide.
MikesXS gave #135, which are short and fat.

So when users on here say go up a size or two, what does that really equate to? Should I get the main jets 125, 127.5, or 130's?

http://www.mikesxs.net/product/48-0210.html

http://www.mikesxs.net/product/48-0211.html

http://www.mikesxs.net/product/48-0212.html


Reccomend needles or pilot jets too?

 

[5twins]

Going up a size or two, sometimes three, is what usually works on the other carb sets but your set is different. Those original 122.5 mains were the smallest ever used in a 650 carb set so you may need to go up more, say 2 to 4 instead of 1 to 3. I wouldn't even bother with the 125s. I would get 127.5s and 130s or 130s and 132.5s if you've changed the exhaust too. Lean the needles a step and get one size larger pilots as well.

Here's the usual scenario - You increase the mains a few sizes which causes some break-up in the upper midrange. You lean the needles a step to correct that. This also leans the upper part of the idle circuit, causing a flat spot there. You increase the pilots a size to correct that.

 

[ipmaham]

Awesome, thanks for the info 5twins. You've always been a big help to me on here. I really appreciate it.

So I will go from
122s, to the 127s or 130s for MJ.
25s to 27.5s for the PJ.
And shoot down from the Z-8 to the Z-6.

Just curious, why lean it down with the needle downsized? Wouldn't the extra air flow from the intake require a wider needle?

 

[5twins]

No, you don't change the needle jet, you simply adjust the clip on your current needle. Your needle has 5 clip slots. Positioning the e-clip higher or lower raises or lowers the height at which the needle sits in the slide. This leans or richens your midrange. The stock position for your carb set is the middle or #3 slot. Move the clip up one to the #2 slot. This will lower the needle in the slide and make it leaner. You have to do this because the larger mains bleed over into the upper midrange and make it too rich.

 

[ipmaham]

You just blew my mind. I was about to go buy another needle jet lol. Surprised I didn't see that a few months ago when I had it apart.

Do you have your own xs650 website or something? All your pictures have watermarks.

Thanks 5twins

 

[5twins]

No web site, just a ton of 650 pics, lol. Most I took myself then cropped, re-sized, and labeled. I realize people are going to use them and I don't mind. The watermark is just a way to get a little credit for my effort. It's so much easier to explain this stuff with the aid of some good pics.

 

[I am Carbon]

And I for one Thank You 5twins for those good pictures.
I have a stash of Your pix in a folder

 

[Lasper01]

I like that 5twins have watermarked his pics, that way I know the "information" the pic gives me is correct comparred to pictures that have carbs blended together of different years and so on.. If I make my self clear (its not allways easy explaining something in another language )