marcush
New member
- Joined
- Dec 24, 2003
- Messages
- 100
Hi guys I an alittle confused on yamaha jetting sizes.Here's my Question going from a # 140 to a 141.3 is this conisered a increase of one jet size or is a 140 to a 142.5 a increase in one jet size?
well in full jet sizes I think your close but I think Yamaha Jet sizes are like a 1/4 of a normal jet..something like that..
marcush
New member
- Joined
- Dec 24, 2003
- Messages
- 100
jetting
thanks for the reply mr sled,the problem I am faced with is I have done several mods to my sled(mm 700) this year and I am looking for some ball park jetting. My jetting before my mods which I will list were #1 cylinder 141.3 ,#2 cylinder 140 and #3 cylinder 140 this jetting was great for 2200 feet @-20 degrees C or 0 degrees F. The mods I have done now are 1)trail porting with head shaved and chambers recut,2)boost bottle,3)carbs bored to 35.5mm and 4)air box mod.I increased my jetting to #1 cylinder 147.5,#2 cylinder 146.3 and #3 cylinder 146.3. I can tell it is running excessively rich.In general people say one size larger jet for each of the following,bored carbs,porting and air box.so if the 1/4 size jets are considered 1 larger size maybe I should consider #1 cylinder 145,#2 cylinder 143.8,#3 cylinder 143.8.WOULD THIS BE CONSIDERED 3 JET SIZES BIGGER OR NOT?
thanks for the reply mr sled,the problem I am faced with is I have done several mods to my sled(mm 700) this year and I am looking for some ball park jetting. My jetting before my mods which I will list were #1 cylinder 141.3 ,#2 cylinder 140 and #3 cylinder 140 this jetting was great for 2200 feet @-20 degrees C or 0 degrees F. The mods I have done now are 1)trail porting with head shaved and chambers recut,2)boost bottle,3)carbs bored to 35.5mm and 4)air box mod.I increased my jetting to #1 cylinder 147.5,#2 cylinder 146.3 and #3 cylinder 146.3. I can tell it is running excessively rich.In general people say one size larger jet for each of the following,bored carbs,porting and air box.so if the 1/4 size jets are considered 1 larger size maybe I should consider #1 cylinder 145,#2 cylinder 143.8,#3 cylinder 143.8.WOULD THIS BE CONSIDERED 3 JET SIZES BIGGER OR NOT?
that would be 3 Yamaha jet sizes..., it will run rich with porting ....that the nice tihng about Yamaha Jets you can get it really close...if its that rich I would drop them back, but watch the piston wash. http://www.totallyamaha.com/snowmobiles/aaTECH/Piston_Wash/Piston Wash.htm
and http://www.eric-gorr.com/tech/pistonguide.html
and http://www.eric-gorr.com/tech/pistonguide.html