carb jetting help

[windjammergump]

81 xs1100 sh.....redone the topend....1179 wiseco running way too lean went from 110 jets to stage one 117.5 on 1 and 4 and 120 in the 2 and 3 running way to rich...took the 4 into 2 off and put a 4 into 1 on still too lean with out rejetting is there any way to lean up the carbs these do not come with adjustable needles for this yr model ..thanks in advance....still trying to get the break in miles on it...have about 300 down so far...

[TopCatGr58]

Hey Jammer,

I created a NEW THREAD for your post, I can see and appreciate you wanting to keep the # of threads down, and found one with a possibly relative topic, but your problem is quite a bit different than the other thread.

Aside from changing jets, you can raise or lower the floats a little to lean or richen them up.

FYI, with my little big bore kit in my 81SH, Indy Pod filters, 4-1 pipes, I went up from 110 to 117.5 across all four, they are running okay, light color on plugs, DYNO showed that I could possibly go up 1 more size to 120, so you're probably very close.

Yamaha felt it wasn't necessary to stagger the jets like you did, you can just put in the same size in all 4. You said the 120's were too rich, or ALL cylinders were too rich??

T.C.

[windjammergump]

all cyclinders are rich

yes all are rich even the ones with the 117.5 and i added a 4 into 1 to help lean but no avail...thanks for any and all help....

[TopCatGr58]

Forgot to ask, what type of intake/filter...OEM airbox or Pods?

Certain cheap (EMGO) brand pods really mess up the air flow thru the intake side and can cause an overly rich condition where there really isn't one..a restrictive LIP on the mounting portion of the pods are responsible. Folks have reported not being able to get the bike/engine up/over ~5k rpm when they are interferring!

If the OEM Airbox, then you can drill a few large holes in the middle of the bottom of the filter box where the filter fits...the holes need to be in the MIDDLE of the filter space..that way it will draw air thru the filter and into the box and then carbs, getting filtered. IF the holes are drilled outside of that area, then you'll be introducing unfiltered air into the box/carbs!

As stated earlier, adjusting the float heights can also provide some mild rich/lean adjustment without changing the jets.

T.C.