xs1000s carbs

[wetassnofish]

hi my 82 xs1100s is fitted with mikuni 36mm carbs, anyone any idea what jets and needles etc it should be fitted with, i have very poor running diaphrams ok carbs have alloy tops no numbers on them because been polished off it has cable operated chocke slide bar, carbs look like standard xs but 36mm instead of 34mm have tried all the combination of needles jets etc recommended but problems with the needles any info greatly appreciated

[pgg]

First up, measure the throats - inside past the groove. 36 or 34mm? If 36mm, I'm picking the air jet and air pilot jet are at a different spec than standard 34's. What's the pilot air jet size? Possibly it's 200 or more. Secondly, what' your exact current carb setup - jets, needle sizes and emulsion tube number, brass or plastic floats, and what's the symptoms of the 'poor running'?

[chevy45412001]

82 xs?

wouldn't 82 make it an XJ ? If so 112.5 stock mains?36mm openings? mine are 34mm ,36's i have but are off of a fj1200?

[pgg]

For an XS those bigger carbs are always going to be far better suited to a better breathing hotted motor eg hot cams, valve work, ported head, bigbore, free flow air system and pipes etc. If running non standard carbs on stock standard motor, all you can really do is experiment with jets, needle size/clip, float heights based on plug colour and rich/lean symtoms. It's preferable to adjust carbs to the slide cutaway but grinding 1mm off the cutaway will richen the fuel flow. It's amatter of persevering to get the right combinations.

[ratbyk]

Larger Carbs

It has been my experience over the years that when you put larger bore carb/s on an engine that you have to richen it up a bit. The reason is that the same amount of air is flowing through the venturi of the carb to feed the engine but the air speed is reduced because of the bigger bore. This means that the amount of vacuum in the venturi area is reduced. This draws less fuel past the mains and pilots causing a lean condition. It can sometimes be overcome simply by raising the float level slightly.
Ken/Sooke
78E Ratbyk
82 FT500 "lilRat"