i recently rebuilt the rappy and now i cant seem to get the jetting right it runs ok it has awesome throttle response but right in the mid-range it stumbles i have lowered the clips changed the main and pilots around but cant seem to get it dialed in im running a 102 mm 12.1 piston sparks mid-range cam lrd dyno jet kit. any help would be appreciated thanx

 

Any air box mods????

 

just the cfm airbox and kand n filter

 

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Have you checked the float level?

 

I agree with sixsixT, I was having the same problem and it was my floats.

 

what do i do to check the float level[img]i/expressions/face-icon-small-blush.gif[/img]

 

The best thing to do is check it before you take it apart, with a piece of clear tubing. You can get the tubing at a hardware store for 20 cents, 1/8" clear tubing.





The quick & easy way to check float levels is to use a clear tube that fits the dump hole on the bottom of the carbs. You'll need at least one foot of tubing. Don't worry about an exact fit, the tubing can be a little bigger which will cause some of the gas to leak out but gravity is forgiving and is constant! You can get the tubing from your Yamaha dealer for a few bucks. Remove the stock dump hole tubing, put the new tubing on there & then bend up the other end and run it along side of the carb with the open end facing up. Then open the drain screw next to where the tube is connected & the level of gas in the tube should fill up & be level with or slightly above the bottom/top half of the carb's mating surface. If not, you'll need to adjust the float levels. A sign that the float levels are too high is if the stock drain tubes leak gas while your riding, you'll smell it for sure.
I just pop the carbs on the boots and set the tank on the frame and hook up the hose to check it again, you may have to take it back off once or twice to get it perfect. I also measure the amount that it is off and then take it apart, measure the float height and then bend the tab enough to raise or lower the float the amount that it was off. If that makes any sense.

 

BAd raptor just a thought try applying your choke when your in mid range . if it smooths out tear your carbs down and look for blockage around the pilots . It dosent take much to screw things up . if it smooths out and theres nothing in your pilots then step up your pilot jet .

Just a thought
Good luck