Looking at the different jets that come in the dynojet kit, i noticed they are all smaller then the one in the stock carb. The needle is also different. Now my stock jet was a 147 or something along those lines, and dynojet suggested a 132 jet. Im running a 138 jet now. Is the diffrence in the needle design what allows the holes in the dynojet jets to be smaller? I can't understand why im running a smaller dynojet jet thats letting more fuel in then the stock jet.

 

All I know is that they really know what they are doing. I would trust them and try it. Worst case senario, you do a plug chop and find it is a little too lean and you go up one or two. The needle taper is probably thinner and so a larger one is not required. It is about the quantity of flow and not the size of the orafice. Dyno jet did wonders for my griz. If the needle doesn't match the main jet, it will affect performance. I would not be surprised if it didn't bog a little when you go full throttle from close to a stop.

 

mikuni dyno conversion chart...try this link..

 

simple....the needle is also thinner....so the amount of open area between the jet and the needle is greater.

The DJ kit attempts to atomize the fuel better by sucking it through a thinner jet. This works great for low end throttle response but often causes a top end lean condition. If you get the top end correct the bottom end goes way rich, higher altitudes seem to have a bigger issue with this.

 

I pulled all my dyno stuff out and round canned it...I just went with all Mikuni stuff.Thats what I found works best and buying a jet from the dealer is a whole lot less money than dumping it into a kit....JMO.

 

Well what jet do you guys think i should go buy from yamaha for my combo?
HMF slipon
K&N filter/outerwear with the lid intact?
Also with the lid modified?