I'm getting a HMF slip on can some one explain why I need to jet the carb. I'm not arguing about doing it I just want to understand the physical reason why I need to do it. And I read some one's post that their snorkle was effecting which size jets they used why is that ?

Also how do I know what kind or size i will need.

 

When you put on a new exhaust you are making the engine breath alot easier because typically the new exhaust system is not as restrictive. the engine is now sucking in more air because it can get the spent gas's out of the cylinder easier. The reason for the jet kit is so that you can maintain the correct air fuel ratio. with out the jet kit the engine would run lean which could cause backfiring, high engine & exhaust temps and poor driveablility. poorly designed snorkle systems can cause a restriction in the intake side of the engine causing a engine to run rich. the opposite is also true, a higher flowing snorkle with little to no restriction is going to allow more air into the engine again like the new exhaust causing the engine to run lean. hope this helps.

 

absolutely helps

 

you don't really need a jet kit, most of the time you can just go with a diffrent main jet. Unless you just wanta buy the kit so that you'll have a assortment of jets to chose from for future mods.

 

are theses pipes loud or do they just have a nice deep sound to them? Cause a few of my friends got FMF pipes and they are just to loud.

 

So how do you know which one to use, do you just keep changing them until it runs right.

 

if you buy the kit yeah you can just change it till it's right. On my setup I emialed FMF and they recomeded a 150 main jet (stock was # 145) with everything else stock. I put it in and it ran way rich......

Well turned out my air fuel mixture screw was out 4.5 turns so i went back to 2 turns out and it worked fine.... Ask around and see what everyone else has tried and you'll get a good idea of where to start