Filling In The Slide

Smooth Slide Adds Power

I suspected as much but wasn't sure until today. I jetted my bike to perfection and then noted how far it could go up a steep hill. It has a Mikuni VM18 with a round slide with the normal step that the air flow encounters. Then I filled in with JBWeld the bottom of the slide so there's one continuous slope from cutaway to the front edge of the slide. But of course I had to make a vacant area around the needle to accommodate the needle shroud when the slide is all the way down. But even with this imperfection the bike had better low and mid range power and climbed farther up the hill. I used to always think that the idle circuit just affected idle but now I know it affects up thru mid range. So if you have an old-style slide you might consider doing this mod. Just plan to increase the idle jet a couple #'s to match the increased flow if the JBWeld doesn't partially cover the needle shroud. If it does cover it then the idle jet may need a really big increase to make up for reduced flow from the needle jet.