vacuum piston XJ 1100

[dodjh]

When the bike is off, if I open the throttle, will the vacuum piston move up and down according to the throttle position?

dodjh

[gareth]

The stock Mikuni carbs on the XS are constant velocity carbs, the vacuum slides move according to how much air the engine is "pulling".
I helped a guy with his CB550k carbs this weekend and twisting the throttle moved the slides up and down...different system. Short answer...no. One of the gurus here posted a video of his carbs in action under load on youtube. Maybe someone could post the link?

[DGXSER]

Links

TopcatGr posted thes on Youtube...Here you go...first no load

http://www.youtube.com/watch?v=sMKGMCimV2w&feature=channel_page

Now under load...at first they are not underload...keep watching you will see the difference. It has to do with vacuum from the engine pulling velocity through the carbs I believe. It creates a vacuum in the top through that half moon shape at the top of the inlet bell. That pulls the slides up.

http://www.youtube.com/watch?v=tR63vrfhwr8&feature=channel_page