Idle Screws

[Cy Welch]

Ok, this weekend I finally removed the blind plugs from my idle mix screws on my 80 xs400G and before doing anything else at all I removed the mix screws. Interestingly, they are NOT pointed be have flat tips!!! Exactly the same length and appear machined this way, and since the unit is sealed (and being the second owner and knowing the first owner didn't open the carbs EVER) I'm pretty sure nobody screwed them in and damaged them.

So, I sprayed carb cleaner into the openings and then blew compressed air through them to clear them out. Then I put the screws back in and took them down carefully (didn't force them at all) then turned them out 2 1/2 turns (no specs for 1980 so I used the 1979 specs) and it does seem better if its a bit warmer out, but if it cold boy it idles bad till the weather warms up. So here is the question, it's a lot better than it used to be (at least it will idle nicely and doesn't backfire like crazy when decelerating anymore) but to make it richer do I turn it in, or do I turn it out? I seem to find conflicting information on this thing, most sites say that a mix screw in this position adjusts amount of fuel and air mix screws are adjusted from the back of the carbs but I have recall having seen here I believe that the bs34's are mixing air and opening them leans the mix. I'm not looking to get real precise quite yet, just trying to take small jumps in the right direction as I know it's still a bit lean so I want to richen it a bit and see how it does. Next payday I'lll probably spring for a colour plug so I can get it precise, but for now it would be nice to get it in the ballpark until then.

Thanks in advance for any help you can give.

[Cy Welch]

Well I found that in is lean and out is rich. I also found that the floats were about 3-4 mm's low so after adjusting them and then adjusting the idle mix it's running really good.