Everytime I get pointed down hill while running at slow speeds my machine starts to sputter and flood out. I did have some float issues where I had trouble setting it to the factory specs so I took it to the shop and had them do it. I'm wondering if it is set too high causing this problem.

 

i think you hit right on the nose. i would say its still not set right if it floods out going down hill.

 

Incorrect float hight can cause this sort of problem.

 

Before I took it into the dealer I tried to set it myself but couldn't get the tab to bend far enough while still allowing the float to move freely as the factory setting was too high according to my calculations. When I got it back from the shop I measured their setting and it too was higher than spec but according to them it was set correctly. Something doesn't seem right and I'm sure it's the float causing this problem. I need someone who has played with the float setting on this carb and tell me what the trick it. I've set many before on other vehicles so I'm pretty sure I'm looking at and doing it according to factory specs.

 

the carb should be about 45 degrees when you measure float height just touching the top of needle valve. I think the factory spec is 13 mm from base of carb. I use a small metal ruler.

 

I haven't tried to set the carb at an angle when measuring it as the manual says to set the carb on a level surface. What I think I might try is to use the clear tube attached to the drain on the carb and measure the fuel height when the machine is running and also when it's at an angle to see what it's doing. Also I was thinking of adjusting the jet needle by raising the clips thereby lowering the needle. I've done this on snowmachines before to get them to lean out in the mid range. Does anyone know what the stock clip settings are?

 

THERE SHOULD BE FOUR SETTINGS FOR THE NEEDEL CLIP.THE FACTORY SETTING IS THESECOND CLIP SLOT.

 

Found a good website for info on Mikuni carbs if anyone is interested. advrider.com. Do a search for BST 40 and you will finds tons of information. This carb was put on motorcyles and there has been lots of discussion on them. Also there are five clip positions on the needle, the factory setting is the middle one. I got my float adjusted and back together now to see if it's going to work better.

 

The machine's running great now. The float setting seemed to be the problem, it took several trial and error runs to get it right but I think I'm good now.