Cafe Racer XS1100 Project- Carb basics

[MarkD]

I came across this video today--- TopCat has a great thread with a cross section of the CV carb, and a good tutorial on how these things work. This guy's drawing and explanation helps me understand the mysteries of the 3 circuits. You might be following this guy's Youtubes, they're pretty good.

https://www.youtube.com/watch?v=Yi4Z8wTOUM8

Enjoy- (but don't hate on me if there's some misinformation, I don't think there is, though). I thought it was very good.

[Prothec]

I really like seeing XS1100-specific how-to videos. I'm sure you can always find something that isn't quite right. If anyone does find problems, I implore them to contact him directly or find a tactful way of commenting without trolling. He delivers well and gives real-world examples, showing real-world results in many of his videos. We need to encourage this type of work.

[TADracer]

Very, very good explanation.

About the only thing I would add is that there is more to the primary circuit other than just the idle mixture. Crack the butterflies a bit and you will see a few staggered holes that gradually uncover as the butterfly plate opens. These are also on the primary circuit and they handle the metering chores up to 1/4 throttle when the midrange (needle jet) circuit comes into play and this is where you do a lot of riding. So dialing in the pilot jet is very important. Also, the timing of when one circuit takes over from the preceding circuit is important. That is why he raised his needle a notch to bring on the fuel from the midrange circuit quicker because his modifications will make the motor demand more fuel more quickly.

I have always been a proponent of tuning a CV carb from the top down. It is a chore to do but does get results. Here is the method I have used for years and yes, if done right it will tune out that nagging stumble you get with pod filters and a high-flowing exhaust.

http://www.factorypro.com/tech/tech_...m_engines.html